BACKGROUND

Xp11.2 translocation/transcription factor E3 (TFE3) rearrangement renal cell carcinoma (RCC) is a rare subtype of RCC with limited clinical and pathological data.

METHODS

Here we present an unusual high-grade Xp11.2 translocation RCC with a rhabdoid feature and SMARCB1 (INI1) inactivation in a 40-year-old man with end-stage kidney disease. The histological examination of the dissected left renal tumor showed an organoid architecture of the eosinophilic or clear neoplastic cells with necrosis and high mitotic activity. In some areas, non-adhesive tumor cells with eccentric nuclei were observed. Immunohistochemically (IHC), the tumor cells are positive for TFE3 and the renal tubular markers (PAX2 and PAX8), and completely negative for SMARCB1, an oncosuppressor protein. Break-apart florescence in situ hybridization and reverse transcription polymerase chain reaction confirmed TFE3 rearrangement on Xp11.2 and the presence of ASPSCR1-TFE3 fusion gene. DNA sequencing revealed a frameshift mutation in exon 4 of SMARCB1 gene.

CONCLUSIONS

It is important to recognize this rare RCC with both TFE3 rearrangement and SMARCB1 inactivation, as the prognosis and therapeutic strategies, particularly targeted therapies for such tumors, might be different.

Malignant infantile osteopetrosis (MIOP) is a rare inherited bone metabolism disorder characterized by increased bone mineral density (BMD) and abnormal hematopoiesis. Hematopoietic stem cell transplantation (HSCT) is currently the only curative therapy for MIOP. However, a higher risk of secondary malignancy occurs in children previously exposed to cytotoxic drugs. Here we report a rare case of a 3-year-old female patient with MiT family translocation renal cell carcinoma (MiTF tRCC), who is a survivor of HSCT for MIOP 2 years earlier. The patient had a complete resection of the tumor. Microscopically, we detected diffusely and papillary-like arranged tumor cells whose cytoplasm was bright and clear. Immunohistochemistry showed tumor cells diffusely expressed TFE3, and fluorescence in situ hybridization (FISH) demonstrated disruption of the TFE3 locus, confirming the diagnosis of Xp11 translocation RCC, the subtype of MiTF tRCC. This case supports the view that chemotherapy exposure is a risk factor for MiTF tRCC and indicates the possible association of HSCT with MiTF tRCC.

Due to advanced imaging techniques, renal cell carcinoma (RCC) is now identified earlier, often in localized stages. As a result, nephron-sparing surgical resection is possible in most cases. The development of new targeted therapies has changed the way metastatic RCC is treated. Despite this positive trend with improved survival rates and expanding treatment options, reliable biomarkers for better predicting disease course are lacking. These are urgently needed to enable personalized therapy based on the treatment-associated risks, the presence of comorbidities, and molecular tumor characteristics. We were able to show that proteins with a regulatory influence on apoptotic signal cascades represent not only promising prognostic markers, but also interesting targets for new therapeutic approaches. Furthermore, our data demonstrate that molecular tests are necessary to correctly classify a RCC with Xp11.2 translocation, since in addition to translocation, amplification can also result in TFE3 activation. Translational research with RCC biomarker identification and establishment, as well as molecular characterization and subtyping of RCCs is required to guide therapeutic decisions and enable personalized medicine in RCC patients.

Objective: To investigate the clinicopathologic characteristics, molecular and genetic features, differential diagnoses and prognosis of fumarate hydratase-deficient renal cell carcinoma (FH-RCC). Methods: The immunohistochemical (IHC) expression of FH in 391 renal neoplasms in tissue chips collected from the Affiliated Hospital of Qingdao University and 971 Hospital of PLA Navy from January 2011 to December 2017 was evaluated. The clinicopathologic data of eight FH negative cases were collected.Polymerase chain reaction (PCR) and sequencing were used to detect the changes in FH gene in three cases. Interphase FISH with a dual color and break-apart probe was applied to detect the TFE3 gene alteration in the cases showing TFE3 protein expression. Results: Among the eight patients, seven were male and one was female, and age ranged from 28 to 50 years (mean 39 years). Tumor size ranged from 3.5 cm to 12.0 cm (mean 7.9 cm). Renal pelvis invasion was identified in six cases, and the tumor emboli in renal vein and inferior vena cava were found in four patients. The cut surface of most tumors was solid, colorful, grayish white or yellow with no clear border showing invasive growth pattern. Microscopically, the tumors showed different proportions of papillary, tubular cystic, cribriform and solid structures. The tumor cells were rounded or polygonal with eosinophilic or amphotropic cytoplasm, round or oval nuclei, and focal large and prominent nucleoli (WHO/ISUP grade 3-4). Two cases had sarcomatoid or rhabdoid components. Intravascular tumor emboli were found in five cases. IHC staining showed most tumors expressed PAX8(7/8), CK19(7/8), vimentin (6/8) and P504s(8/8). However, other immunomarkers including CK7, CD10, CD117, RCC, 34βE12, HMB45 and Melan A were all negative. Sequencing showed all three cases had FH gene mutations in exon 1. FISH revealed no TFE3 gene translocation or amplification in the two cases with TFE3 IHC expression. Follow-up data were available in seven patients with the follow-up period from 11 to 66 months. Among them, five patients died between 11 to 31 months after the surgery because of extensive distant metastases of the tumor to the lung, liver and lymph nodes. The other two patients were alive at the 36th and 66th month after the surgery. Conclusions: Morphologically, FH-RCC overlaps with papillary RCC, collecting duct carcinoma and tubular-cystic RCC, showing a mixture of papillary, tubular cystic, cribriform or tubular papillary structures with at least focal large and prominent nucleoli. The negative expression of FH and the detection of FH gene mutation could facilitate the diagnosis of the tumor. FH-RCC is a high aggressive tumor, prone to metastasize, and is associated with poor prognosis. The timely diagnosis of FH-RCC could benefit the patients and their relatives as well.

Background: Renal Cell Carcinoma (RCC) is the ninth leading cause of death among kidney cancer. Xp11.2 translocation harboring TFE3 fusion proteins, act as an oncogene in translocation cancers that constitute the hallmark of translocation renal cell carcinoma (tRCC). G-quadruplex (G4), an alternative nucleic acid structure is an emerging and promising factor in cancer. The presence of G4 within the genome plays a pioneering role in cancer as it contributes to genomic aberration as well as inhibition in cell proliferation.

Scope of review: Here we discuss the link between G4 and tRCC. We compile the available information of G-quadruplex & propose their dual role in tRCC, suggesting both stabilization and destabilization of G-quadruplex could be considered targets for tRCC.

Major conclusions: Our in Silico analysis of TFE3 and their three fusions partner's PRCC, SFPQ, and ASPSCR1 discloses a few putative G4 forming sequences (PQS) in their corresponding fusion gene or fusion transcript. Stabilization of G4 structure within fusion gene/transcript can be of great use towards potential therapeutics targeting fusion protein derived oncogenesis, as G4 is a serious menace for DNA polymerization, transcription & translation. G-quadruplex at intron-2 of the TFE3 has been reported to mediate its translocation also. Both stabilization and destabilization of the G4 structure would be a promising approach in the suppression of cancerous cell proliferation.

General significance: Pioneering studies discovered the relevance of G4 in cancer therapy and explore our approaches towards therapeutic innovation against oncogenic fusion protein and tRCC. Selectively targeting G4 in oncogenic fusion transcript will emerge as potential druggable structures.

Keywords: G-quadruplex; TFE3 fusion protein; Translocation renal cell carcinoma; Xp11.2 translocation.

Angiomyolipoma is the prototype of renal perivascular epithelioid cell (PEC) lesions whose pathogenesis is determined by mutations affecting TSC genes, with eventual deregulation of the mTOR pathway. It is well known that mTOR complex protein is involved in autophagy, and recently the role of STING in this process has been demonstrated. Based on this background, we sought to investigate STING immunohistochemical expression in a series of PEC lesions of the kidney. Fifty classic angiomyolipomas, 14 epithelioid angiomyolipomas/pure epithelioid PEComas, two angiomyolipomas with epithelial cysts (AMLEC), and two intraglomerular PEC lesions were collected. Immunostaining for STING was carried out in all cases and FISH analysis using dual colour break apart TFE3 and TFEB probes was performed in all pure epithelioid PEComas and AMLEC. Control cases including 20 normal adult kidneys, five fetal kidneys, and 30 MiT family translocation renal cell carcinomas (the main differential diagnosis with epithelioid angiomyolipoma/pure epithelioid PEComa) were also immunohistochemically stained with STING. Strong and diffuse cytoplasmic expression of STING was observed in 100% of classic angiomyolipomas, AMLEC, and intraglomerular lesions, and in 79% (11/14) of epithelioid angiomyolipomas/pure epithelioid PEComas. TFE3 gene rearrangement was demonstrated in two epithelioid angiomyolipomas/pure epithelioid PEComas, both completely negative for STING. None of the MiT family translocation renal cell carcinomas expressed STING. In conclusion, we demonstrate the expression of STING in almost all PEC lesions of the kidney. This result provides novel insights into the possible role of autophagy in PEC lesions of the kidney. Moreover, this finding may be useful for diagnostic purposes, particularly in distinguishing epithelioid angiomyolipoma/pure epithelioid PEComa from MiT family translocation renal cell carcinoma and detecting intraglomerular PEC lesions.

Keywords: Angiomyolipoma; MiT family translocation renal cell carcinoma; PEComa; STING; TFE3; autophagy; tuberous sclerosis.

In children, renal cell carcinoma (RCC) is rare. This study is the first report of pediatric patients with RCC registered by the International Society of Pediatric Oncology-Renal Tumor Study Group (SIOP-RTSG). Pediatric patients with histologically confirmed RCC, registered in SIOP 93-01, 2001, and UK-IMPORT databases, were included. Event-free survival (EFS) and overall survival (OS) were analyzed using the Kaplan-Meier method. Between 1993-2019, 122 pediatric patients with RCC were registered. Available detailed data (n=111) revealed 56 localized, 30 regionally advanced, 25 metastatic, and no bilateral cases. Histological classification according to WHO 2004, including immunohistochemical and molecular testing for transcription factor E3 (TFE3) and/or EB (TFEB) translocation, was available for 65/122 patients. In this group, the most common histological subtypes were translocation type RCC (MiT-RCC) (36/64, 56.3%), papillary type (19/64, 29.7%), and clear cell type (4/64, 6.3%). One histological subtype was not reported. In the remaining 57 patients, translocation testing could not be performed, or TFE-cytogenetics and/or immunohistochemistry results were missing. In this group the most common RCC histological subtypes were papillary type (21/47, 44.7%) and clear cell type (11/47, 23.4%). Ten histological subtypes were not reported. Estimated 5-year (5y) EFS and 5yOS of the total group was 70.5% (95%CI:61.7-80.6%) and 84.5% (95%CI:77.5-92.2%), respectively. Estimated 5yOS for localized, regionally advanced, and metastatic disease was 96.8%, 92.3%, and 45.6%, respectively. In conclusion, the registered pediatric patients with RCC showed a reasonable outcome. Survival was substantially lower for patients with metastatic disease. This descriptive study stresses the importance of full, prospective registration including TFE-testing. This article is protected by copyright. All rights reserved.

Keywords: pediatric; renal cell carcinoma; survival; treatment.

Recently, rare renal cell carcinomas (RCCs) have been reported to closely mimic hemangioma; however, these have been largely recognizable as clear cell RCC. Conversely, true hemangiomas of the kidney are also increasingly recognized. We report a 62-year-old woman who underwent partial nephrectomy for a hemangioma-like RCC without appreciable clear cell morphology. Immunohistochemistry revealed luminal structures that stained positively for cytokeratin, cytokeratin 7, carbonic anhydrase IX, PAX8, and high-molecular-weight keratin, admixed with a CD34-positive, CD31-positive, and ERG-positive complex network of vessels. Staining was minimal for α-methyl-acyl-coA-racemase and EMA, and absent for GATA3, HMB45, melan-A, and cathepsin K. Fluorescence in situ hybridization revealed no TFE3 or TFEB rearrangement, 3p deletion, or trisomy 7 or 17. This case adds to the spectrum of hemangioma-like RCC with differing morphology and immunophenotype. Further study will determine whether this represents a distinct entity or an unusual pattern of degenerative changes in an existing entity.

Background: Xp11.2 translocation renal cell carcinoma (tRCC) is recently recognized. As Xp11.2 tRCC involved gene translocation and fusion in X chromosome and the number of X chromosomes in female is twice of male, we wondered whether the gender difference of attack rate is consistent with the proportion of the X chromosome.

Methods: In the present paper, meta-analysis was performed to find out the difference of morbidity between male and female.

Results: Nine studies with 209 cases calculated. Odds ratios (ORs) and ORs with 95% confidence intervals (CIs) were calculated for attack rate of Xp11.2 RCC with different gender. The result showed that the attack rate of female was higher than that of male with pooled OR of 2.84 (95% CI = 1.48-5.45), while the rate rises even further in adult (OR = 3.37, 95% CI =2.19-5.18). In other types of common kidney cancer, the OR value is less than 1, which means that the incidence of female is lower than that of male.

Conclusions: The result showed that the incidence rate of female patients is much higher than that of male patients with Xp11.2 tRCC, it was reasonable to indicate that this particular incidence rate is related to the X chromosome.

Keywords: Gender; TFE3; X chromosome; Xp11.2; tRCC.

OBJECTIVE

To study the expression and clinical significance of kidney injury molecule-1 (KIM-1) in primary and metastatic renal epithelial neoplasms.

METHODS

A total of 136 cases of kidney neoplasms were retrospectively reviewed including 63 primary clear cell renal cell carcinomas (RCCs), 22 papillary RCCs, 13 chromophobe RCCs, 7 oncocytomas, 7 RCCs associated with Xp11.2 translocation/TFE3 gene fusions and 24 metastatic clear cell RCCs. Immunostaining for KIM-1 and kidney-specific-protein (Ksp)-cadherin were performed and the relationship to tumor stage and grade in clear cell RCCs was investigated.

RESULTS

Expression of KIM-1 was detected in 77.8% (49/63) of clear cell RCCs, 90.9% (20/22) of papillary RCCs, 1/13 of chromophobe RCCs, 7/7 of RCCs associated with Xp11.2 translocation/TFE3 gene fusions and 87.5%(21/24) of the metastatic RCCs, but not detected in 7 cases of oncocytomas. A diffuse expression of KIM-1 was more frequently observed in Furhman nuclear grade III/IV clear cell RCCs (P = 0.010). Ksp-cadherin expression was mainly observed in chromophobe RCCs and oncocytomas.

CONCLUSIONS

KIM-1 is a specific biomarker for injuried kidney proximal tubules and the corresponding neoplasms, and has a high specificity and sensitivity for primary or metastatic clear cell RCCs, papillary RCCs and RCCs associated with Xp11.2 translocation/TFE3 gene fusions. Combination of KIM-1 and Ksp-cadherin immunostaining can lead to a more precise histological classification of primary kidney epithelial neoplasms and improve the diagnostic accuracy of metastatic RCCs.

Objective: To investigate the clinical, histologic and immunophenotypic features, genetic alterations and prognosis of the rare Xp11 neoplasm with melanocytic differentiation. Methods: Twenty-one cases were selected from the Department of Pathology, Jingling Hospital, Nanjing University School of Medicine from May 2008 to May 2018. The clinicopathologic, immunohistochemical, molecular analysis and follow-up details were collected. Results: There were 7 males and 14 females, with their ages ranging from 4 to 57 years (mean 32.8 years). The tumors were located in kidney (11 cases), pelvis (three cases), and in pancreas, retroperitoneum, adrenal gland, small intestine, prostate, cervix and appendix (one case each). Microscopically, most tumors shared similar morphology such as purely nested or sheet-like architectures separated by a delicate vascular network, purely epithelioid cells with clear to granular eosinophilic cytoplasm, lacks of papillary structures, spindle cell or fat components, uniform round to oval nuclei with small visible nucleoli, and in most of them (16/21) melanin pigment. Immunohistochemically, all cases showed moderately (2+) or strongly (3+) positive staining for TFE3 and Cathepsin K. HMB45 and Melan A were focally expressed in three of 21 cases, while the remaining cases showed typically moderate(2+) or strong (3+) expression. None of the cases were immunoreactive for SMA, desmin, CKpan, S-100 and PAX8. All cases showed TFE3 rearrangement using fluorescence in-situ hybridization (FISH). Fusion FISH assays detected SFPQ-TFE3 gene fusion in 16 cases, NONO-TFE3 gene fusion in two, ASPL-TFE3 and MED15-TFE3 gene fusions in one case each. Polymerase chain reaction and direct sequencing detected SFPQ-TFE3 gene fusion in nine cases, NONO-TFE3 and MED15-TFE3 gene fusions in one case each. Clinical follow-up was available for 15 patients for 12 to 74 months. Six patients died of the disease; and three had recurrences and/or metastases. Six patients were alive with no evidence of disease after initial resection. Conclusions: Xp11 neoplasm with melanocytic differentiation has unique morphologic, immunophenotypic and genetic characteristics. The tumor is aggressive, and should be differentiated from Xp11 translocation RCC and perivascular epithelioid cell tumor.

BACKGROUND

Melanotic Xp11 translocation renal cancer (TRC) is a newly described exceedingly rare tumor, and its characterization remains controversial. This study aimed to describe a case of distinctive melanotic Xp11 TRC and to elucidate its clinicopathological and molecular genetic features.

METHODS

A 44-year-old Chinese female presented with a left renal mass. Abdominal ultrasonography and computed tomography (CT) scans revealed a 4.5 cm × 4.0 cm mass in the left kidney. Grossly, the well-demarcated mass was black with moderately firm consistency. Microscopic examination indicated that the tumor was characterized by the presence of nests and cords of polygonal cells with clear and granular eosinophilic cytoplasm, central round to oval nuclei and occasional nucleoli. Intracytoplasmic melanin was observed in approximately 45% of tumor cells. Uniquely, the tumor presented with intranuclear eosinophilic pseudoinclusions and thick-walled stromal blood vessels. IHC showed that tumor cells were diffusely positive for TFE3 and exhibited patchy and weak HMB45 staining. FISH confirmed the presence of TFE3 rearrangement.

CONCLUSIONS

This case is the twentieth published case of melanotic Xp11 TRC. Moreover, the present patient had a favorable prognosis given that she was disease free at her 113-month postoperative follow-up. Our case adds to the small body of literature on these exceptionally rare tumors and widens their clinicopathological spectrum.

Primary lung tumors arising in pulmonary sequestration is an exceptional event, usually consisting of common histologic types. On the other hand, malignant perivascular epithelioid cell (PEComatous) tumors with deposition of melanin pigment have never been reported in the lung so far. In this study, we report a challenging case of a 34-year-old man presented with recurrent hemoptysis and CT scan detection of a pulmonary mass at the left lower lobe, vascularized by aberrant communication with the left diaphragmatic artery. After surgical resection, we documented a malignant PEComatous tumor (characterized by TFE3 expression and high mitotic rate) that had arisen in the context of an extralobar sequestration.

Epithelioid hemangioendothelioma (EHE) is a rare medium-to-low-grade malignant vascular tumor characterized by vascular differentiation along with specific morphological and genetic alterations. Approximately 90% and 5% of EHE cases are associated with the WWTR1-CAMTA1 and YAP1/TFE3 fusion gene, respectively. Therefore, nuclear CAMTA1 protein expression is considered to be an effective marker for EHE diagnosis. However, the specificity and reliability of this approach have recently been put into question. The purpose of this study was to compare the detection of CAMTA1 expression in cases of EHE and histologic mimics using fluorescence in situ hybridization (FISH) and conventional protein immunohistochemistry via hematoxylin and eosin staining. Fifteen EHE and 37 histologic mimic samples were immunohistochemically stained with polyclonal anti-CAMTA1 antibody to evaluate the nuclear protein expression level of CAMTA1. In addition, 15 EHE samples and 10 vascular tumor samples were subjected to FISH to detect the WWTR1-CAMTA1 fusion gene. Histologically, EHE typically showed a mucous hyaline or cartilaginous stroma, often forming a primitive vascular lumen, and expressed vascular endothelial markers. Twelve of the 15 EHE samples showed positive nuclear CAMTA1 expression with immunohistochemistry, whereas six of the 37 histologic mimics showed positive nuclear expression. FISH detected a red-green signal fusion in 14 of the 15 cases of EHE, but in none of the 10 vascular tumors. These results indicate that CAMTA1 is an effective and useful EHE marker, but that FISH fusion gene detection has better diagnostic value and clinical significance.

Keywords: CAMTA1; FISH; epithelioid hemangioendothelioma; immunohistochemistry.

Renal cell carcinoma is a rare pediatric malignant tumor of the kidney. Unlike Wilms tumor, the efficacy of chemotherapy and radiation therapy in pediatric renal cell carcinoma remains uncertain. Surgery is the best treatment and prognosis is favorable when the tumor is localized and completely eradicated. We report an exceptional observation in a 7-year-old girl with renal cell carcinoma who had been treated 20 months previously for Ewing sarcoma with chemotherapy and radiotherapy. The renal tumor was revealed by abdominal pain without hematuria. She underwent a radical nephrectomy, and histopathology concluded in renal carcinoma associated with translocation Xp 11.2 grade 3 of Furhrman pT3a N1. No adjuvant therapy was given. After 3 years of follow-up, there is no evidence of local or metastatic recurrence. This observation is significant given the very young age of this patient, the occurrence after Ewing sarcoma with a short disease-free interval. It seems that translocation renal cell carcinoma is associated with previous exposure to chemotherapy, particularly topoisomerase II inhibitors or alkylating agents.

Mammalian TFEB and TFE3, as well as their ortholog in Caenorhabditis elegans HLH-30, play an important role in mediating cellular response to a variety of stress conditions, including nutrient deprivation, oxidative stress, and pathogen infection. In this study, we identify a novel mechanism of TFEB/HLH-30 regulation through a cysteine-mediated redox switch. Under stress conditions, TFEB-C212 undergoes oxidation, allowing the formation of intermolecular disulfide bonds that result in TFEB oligomerization. TFEB oligomers display increased resistance to mTORC1-mediated inactivation and are more stable under prolonged stress conditions. Mutation of the only cysteine residue present in HLH-30 (C284) significantly reduced its activity, resulting in developmental defects and increased pathogen susceptibility in worms. Therefore, cysteine oxidation represents a new type of TFEB post-translational modification that functions as a molecular switch to link changes in redox balance with expression of TFEB/HLH-30 target genes.

Keywords: HLH-30; TFE3; TFEB; glutathionylation; lysosomes.

Background: Pancreatic Solid Pseudopapillary Neoplasms (SPNs) are rare low-grade malignant tumors with a marked preponderance for young females. Objective was to describe the morphology, differential diagnosis, and prognosis of SPNs in patients under 20 years of age and present a detailed review of literature.

Methods: A total of 29 cases in patients under 20 years of age reported as SPN during the period January 2014 to December 2019, were included in the study. These included 19 resection specimens, 4 incision biopsies and 6 cases received as blocks for second opinion. Hematoxylin and eosin (H&E) slides as well as immunohistochemistry (IHC) slides of all cases were retrieved and reviewed by the authors. TFE3 and Progesterone Receptor were performed retrospectively.

Results: Twenty-eight of the 29 patients were females. Ages of patients ranged from 12 to 19 years. Nineteen cases were resections. Tail was the commonest location. Mean tumor size was 9.5 cm. In 89.5% cases, tumor was confined to the pancreas. In 2 cases, distant metastasis was present. In 2 cases, extension beyond pancreas was seen. Solid and pseudopapillary areas were seen in all cases while other features were variable. Beta catenin and Cyclin D1 were positive in most cases while TFE3 was positive in 57% cases. Progesterone Receptor (PR) was positive in all 13 cases in which it was performed. Follow up was available in 14 patients. Follow up period ranged from 3 to 70 months. Twelve were alive and well without recurrence or metastasis while 2 were alive with recurrence and metastasis to liver and omentum respectively.

Conclusions: Although many studies on SPNs have been published, surgeons, oncologists and even pathologists in this part of the world are often not aware of these rare tumors leading to inaccuracies and delays in diagnosis. In addition, this paper focusses on the interesting observation that the majority of SPNs diagnosed in our department during study period occurred in patients under 20 years of age (29 versus 21 in patients over 20). However, clinico-epidemiological, morphologic and prognostic features were similar in both age groups. Possibility of SPNs should always be considered in case of pancreatic neoplasms occurring in patients under 20 years of age as well. We believe that this is a very interesting and helpful study for the clinicians as well as the pathologists.

Keywords: Excellent prognosis; Low-grade malignant tumor; Pancreas; Progesterone receptor; Solid pseudopapillary neoplasm (SPN); TFE3; Young females.

Alveolar soft part sarcoma (ASPS) is a rare soft tissue sarcoma, often occurs in adolescents and young adults with a particular predilection for the deep soft tissue of extremities. Occurrence of ASPS in the female genital tract is very uncommon and poses a significant diagnostic challenge. A case of ASPS of the uterine corpus is described in a young unmarried female, who presented to the out-patient clinic of our Institute with complaints of abnormal uterine bleeding for the past 9 mo. She was being treated with oral contraceptive pills, progesterone and tranexamic acid. Following radiological imaging and hysteroscopy, a therapeutic curettage of the lesion was done. The histopathologic features raised a differential diagnosis of a myriad of morphologic mimickers. The diagnosis was clinched by exclusion of mimickers by relevant immunohistochemical markers and strong nuclear expression of TFE3 on immunohistochemistry. The patient is on regular follow-up with oral contraceptives and antifibrinolytic medication. Despite being infrequent at this location, ASPS should be kept in differential diagnosis in young females presenting with abnormal uterine bleeding.

Alveolar soft part sarcoma (ASPS) is infrequent in children. While head and neck locations, including the orbit and tongue, are described, only six cases of sinonasal ASPS are reported in the literature. We report two cases of pediatric oro-maxillofacial ASPS. The first case presented as a sinonasal mass in a 13-year-old girl, while the second was a tongue lesion in a 4-year-old female. Histologic examination, TFE3 immunopositivity, and ultrastructural findings of rhomboid crystalline inclusions helped confirm the diagnosis. The diagnosis of ASPS is challenging in children and in uncommon sites like the head and neck. Patients should be routinely followed up for detection of residual or recurrent disease, particularly in cases with positive resection margins.

Keywords: Alveolar soft part sarcoma; Electron microscopy; Head and neck; Immunohistochemistry; Pediatric; Sinonasal.

Background: Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal tumor that exhibits an epithelioid and spindle cell morphology. The tumor is characterized by immunoreactivity for melanocytic and myogenic markers but can be misdiagnosed as more common tumors with similar characteristics, including gastrointestinal stroma tumors or leiomyosarcomas. Recently, a subset of PEComas has been reported to harbor a transcription factor binding to TFE3 fusion. Herein, we report a rare case of TFE3-expressing malignant PEComa arising from the mesentery.

Case summary: A 50-year-old woman presented with abdominal discomfort for 3 months. Results of laboratory tests were all within the normal ranges, and the patient had no notable medical history. Magnetic resonance imaging revealed a large tumor on the right side of the pelvic floor, which was originally suspected to be a primary ovarian tumor. However, during surgery, the tumor was revealed to have originated from the mesentery. Histologically, the tumor was composed of bundles of spindle cells and sheets of epithelioid cells. Extensive coagulative necrosis and numerous mitotic figures were observed. Immunohistochemistry revealed that the tumor cells were positive for smooth muscle actin, HMB-45, and TFE3 expression. Tumor involvement of the rectal serosa was identified, leading to a final diagnosis of malignant PEComa of the mesentery. Surgical resection was followed by adjuvant chemotherapy. No recurrence or metastasis was observed over a 6-month follow-up period.

Conclusion: Malignant PEComa of the mesentery is extremely rare and should be distinguished from morphological mimics through differential diagnosis and immunohistochemistry.

Keywords: Case report; Differential diagnosis; Histology; Mesentery; Perivascular epithelioid cell tumor; TFE3.

Perivascular epithelioid tumors (PEComas) are a family of mesenchymal neoplasms that have smooth muscle and melanocytic differentiation. They can be sporadic or associated with Tuberous Sclerosis Complex and commonly present in the kidney as angiomyolipoma or in the lung as pulmonary clear cell sugar tumors or lymphangioleiomyomatosis. However, they can present at any visceral or soft tissue site. They usually have a benign clinical course, but rarely can behave in a malignant fashion. Most PEComas demonstrate abnormalities of TSC2, but a recently described subset harbor TFE3 rearrangements that appear to be mutually exclusive of TSC2 alterations. TFE3 rearranged PEComas demonstrate a distinct alveolar morphology that lacks spindle cells and smooth muscle differentiation. Distinction between these may have important therapeutic consequences. Herein, we present a case of a TFE3 rearranged PEComa without the customary morphology that required ancillary investigation with TFE3 immunohistochemistry and break-apart fluorescence in-situ hybridization (FISH) for proper categorization.

We previously confirmed a unique and unanticipated role for an α2 integrin, extracellular matrix metalloproteinase inducer (Emmprin), and matrix metalloproteinase (MMP)-3-mediated signaling cascade, in driving the odontoblast-like differentiation of mouse embryonic stem (ES) cells in a collagen type-I scaffold (CS) combined with bone morphogenetic protein (BMP)-4 (CS/BMP-4). To explore the early signaling cascade for odontoblastic differentiation, we examined the upregulation of autophagy-related gene (Atg) and Wnt signaling by CS/BMP-4 mediated odontoblast differentiation. In a screening experiment, CS/BMP-4 increased the mRNA and protein levels of Atg5, Lrp5/Fzd9 (an Atg5 receptor), and Wnt5, but not microtubule-associated protein 1 light chain (LC3; a mammalian homolog of yeast Atg8), TFE3, Beclin1, and Atg12, together with the amount of autophagosomes and autophagy fluxes. Treatment with siRNAs against Atg5 and Wnt5 individually suppressed the CS/BMP-4-induced increase in odontoblast differentiation. The odontoblastic phenotype, involving dentin matrix protein-1 and dentin sialophosphoprotein expression, decreased when autophagy was inhibited by chloroquine, but increased after treatment with rapamycin (an autophagy enhancer). Taken together with our previous findings, we have revealed a unique sequential cascade involving Atg5, Wnt5a, α2 integrin, Emmprin, and MMP-3. This cascade results in a potent increase in odontoblastic cell differentiation, indicating the unique involvement of Atg5, autophagy and Wnt5 signaling in CS/BMP-4-induced differentiation of ES cells into odontoblast-like cells, at a relatively early stage.

PRCC-TFE3 translocation renal cell carcinomas (tRCC) was a common subtype of TFE3 tRCCs in which TFE3 fusions were indicated as oncogene to promote tumor development. PRCC-TFE3 fusions are often accumulated in nucleus and related to poorer outcomes and higher stages (III/IV). In this study, we found that PRCC-TFE3 could positively regulate expression of both Dynamin-related protein 1 (Drp1) and fission protein1 (Fis1), and alter distribution of mitochondria, which could promote cell migration and invasion independent on matrix metalloproteinase-2 (MMP-2) and MMP-9. Together, our findings showed a new mechanism for PRCC-TFE3 tRCC cell migration and invasion by alteration of mitochondrial dynamics. Thus, targeting dysregulated Drp1-dependent mitochondrial fission may provide a novel strategy for suppressing the progression of PRCC-TFE3 tRCC. This article is protected by copyright. All rights reserved.

Objective: To investigate the expression status and diagnostic value of SRY related high mobility group box 11 (SOX-11) and transcription factor E-3 (TFE3) in solid pseudopapillary tumors of pancreas (SPTPs). Methods: Thirty-eight cases of SPTPs, 36 cases of well-differentiated pancreatic neuroendocrine tumors (PanNETs) and six cases of pancreatic acinar cell carcinomas (PACCs) were collected at the Affiliated Drum Tower Hospital of Nanjing University Medical School from 2012 to 2019. The expression of SOX-11, TFE3 and β-catenin was detected by immunohistochemistry, and the TFE3 gene status was detected by FISH in 18 cases of SPTPs. Results: Among the 38 SPTP patients, 29 were female and 9 were male, with a mean age of 50 years; among 36 PanNET patients, 32 were female and 4 were male, with a mean age of 39 years; for the six PACC patients, four were male and two were female, with a mean age of 60 years. β-catenin was positive in all 38 SPTPs, but was negative in all 36 PanNETs and 5/6 PACCs. SOX-11 was positive in 35/38 (92.1%) of SPTPs, but was negative in all 36 PanNETs and 6 PACCs. TFE3 was positive in 36/38 (94.7%) of SPTPs, but was negative in all 36 PanNETs and 6 PACCs. Among these three tumors, the specificity and sensitivity of β-catenin were 97.6% and 100.0%, the specificity and sensitivity of SOX-11 were 92.1% and 100.0%, the specificity and sensitivity of TFE3 were 94.7% and 100.0%, respectively. There was a significant difference of the expression status of all three markers in SPTPs compared with PanNETs and PACCs (P<0.01). The results of SOX-11 and TFE3 immunostaining showed high consistency (Kappa>0.6). No gene rearrangement (0/18) of TFE3 was found in SPTPs. Conclusion: SOX-11 and TFE3 are highly expressed in SPTPs, and their specificity in the differential diagnosis of SPTPs is better than that of β-catenin.

目的： 探讨SRY相关的高迁移率组盒蛋白-11（SOX-11）及转录因子E3（TFE3）在胰腺实性假乳头状肿瘤（SPTP）中的表达情况及其在鉴别诊断中的价值。 方法： 收集南京鼓楼医院病理科2012—2019年间38例SPTP，36例胰腺神经内分泌肿瘤（PanNET）和6例胰腺腺泡细胞癌（PACC）患者资料，采用免疫组织化学EnVision法检测SOX-11、TFE3及β-catenin的表达情况，采用荧光原位杂交（FISH）法检测18例SPTP中TFE3基因重排情况。 结果： 38例SPTP患者中，女性29例，男性9例，平均年龄50岁；36例PanNET患者中，女性32例，男性4例，平均年龄39岁；PACC患者6例，男性4例，女性2例，发病平均年龄60岁。38例SPTP均为β-catenin阳性，36例PanNET均为β-catenin阴性，5/6例PACC为β-catenin阴性；35/38（92.1%）SPTP为SOX-11阳性，36例PanNET及6例PACC均为SOX-11阴性；36/38（94.7%）SPTP为TFE3阳性，36例PanNET及6例PACC均为TFE3阴性。β-catenin的特异度与灵敏度分别为97.6%和100.0%，SOX-11的特异度与灵敏度分别为92.1%和100%，TFE3的特异度与灵敏度分别为94.7%和100.0%。三种抗体在SPTP、PanNET、PACC中的表达差异有统计学意义（P<0.01），且SOX-11、TFE3检测结果具有较高的一致性（Kappa>0.6）；SPTP中并未检出TFE3基因重排（0/18）。 结论： SOX-11和TFE3在SPTP中高表达，且二者在SPTP鉴别诊断中的特异度优于β-catenin。.

Keywords: Diagnosis, differential; Pancreatic neoplasms; SOXC transcription factors; Solid pseudopapillary tumor; TFE3.