Aims: Uterine plexiform tumorlets are traditionally regarded as microscopic epithelioid leiomyomas. They are typically solitary incidental findings but may be multifocal (plexiform leiomyomatosis). We aim to report novel immunohistochemical and morphological findings, specifically the presence of spindled and epithelioid cell nodules, in these lesions.

Methods and results: Three cases of plexiform leiomyomatosis and 16 solitary plexiform tumorlets were included. Two cases of plexiform leiomyomatosis and four solitary plexiform tumorlets demonstrated spindled and epithelioid cell nodules which in one of the former cases formed expansile masses up to 15mm. The nodules demonstrated mild cytological atypia and occasional mitotic activity, and they were associated with a myxoid stroma and a lymphohistiocytic infiltrate which imparted a granulomatous appearance to the microscopic lesions. The plexiform tumorlets (solitary and multifocal) consistently expressed desmin, smooth muscle actin, ER and PR, and they commonly co-expressed melanocytic and perivascular epithelioid cell (PEC) markers HMB45, MiTF and cathepsin K. The spindled and epithelioid cell nodules were generally negative for myoid markers and hormone receptors but they expressed p16, cyclin D1 and TFE3. All lesions tested were negative for cytokeratin, S100, melanA, inhibin, EMA, ALK and BCOR; fluorescence in situ hybridization was negative for ALK, TFE3 and BCOR rearrangements in one of the larger spindled and epithelioid cell nodules.

Conclusions: Plexiform tumorlets commonly co-express myoid and melanocytic markers and may represent part of the spectrum of gynaecological PEC-related lesions. Some cases are associated with spindled and epithelioid cell nodules that could potentially mimic other uterine myxoid neoplasms.

Keywords: PEComa; myxoid; perivascular epithelioid cell; plexiform tumorlet.

Perivascular epithelioid cell neoplasms (PEComas) of the bladder are extremely rare, with ~30 case reports. A subset of PEComas contain TFE3 gene rearrangement, however, the distinct histomorphologic features of these translocation tumors has not been fully explored in bladder PEComas. In our series, 11 cases of bladder PEComas were collected, including 1 internal and 10 consults, with 1 case previously reported. There was a female predominance (9 female, 2 male) with a mean age of 44.2 years (24 to 61 y). In only 1 of the 10 consult cases was PEComa considered in the differential diagnosis. In 10 of 11 cases, prominent epithelioid features were noted, with the final case having focal epithelioid morphology. Mitotic rate was increased in 2 of 11 cases, and 2 of 11 cases had cytological atypia. Two cases were malignant, with invasion into perivesicle tissue in 1 case, and metastases to lungs and brain followed by death in the other case. Immunohistochemically, there was strong, and diffuse staining for cathepsin K in 10/11 cases with the 1 negative case restained on a previously stained slide. HMB-45 was diffusely positive in 8/11 cases, while melan-A was present in only 1/10 cases. Muscle markers were variably expressed with positivity for both smooth muscle actin in 6/10 cases and desmin in 3/10 cases. Keratin AE1/3 was uniformly negative (0/11). In 5/8 cases where TFE3 was rearranged by fluorescence in situ hybridization, the morphology had a predominantly epithelioid, nested architecture. Overall, bladder PEComas are particularly difficult to diagnose given their rarity, are predominantly epithelioid and do not always express melanocytic markers. Diagnosis in the bladder requires a combination of morphologic characterization, exclusion of other diagnostic possibilities, positive Cathepsin K staining, variable melanocytic marker expression, with some cases showing a TFE3 gene rearrangement.

Xp11.2 translocation/TFE3 rearrangement-associated renal cell carcinoma (RCC) and Xp11 translocation renal mesenchymal tumor are distinct tumor entity. To broaden the spectrum of Xp11 neoplasms, we investigated a novel tumor exhibiting morphologies overlapping Xp11.2 translocation/TFE3 rearrangement-associated RCC and the mesenchymal counterpart with melanocytic differentiation by immunohistochemistry, fluorescence in situ hybridization (FISH) and RNA sequencing, as well as literature review. Histologically, the tumor was composed of three different types of tumor cells, including a large proportion of clear cells, small round cells, and a few spindle cells, presenting a relatively clear border in the majority area. The nuclei of all tumor cells showed extensively and strong positive expressions of TFE3. Whereas, the clear cells positively expressed the RCC-related markers including PAX8, RCC marker and CD10, and negatively expressed HMB45; On the contrary, the small round cells and spindle cells positively expressed melanocytic marker HMB45, and negatively expressed PAX8, RCC marker and CD10. The ki67 index was higher in the small round cells and spindle cells than that in the clear cells. FISH revealed the rearrangement of TFE3 gene in all the three types of cells. The NONO-TFE3 fusion gene was detected in all tumor cells by RNA sequencing. This unique Xp11 translocation-associated neoplasm might represent a distinct entity overlapping Xp11 translocation RCC and the mesenchymal counterpart with melanocytic differentiation, broadening the spectrum of Xp11 neoplasms. The patient died of tumor recurrence and lung metastasis after seven months after the surgery suggesting those tumors have an unfavorable prognosis.

Acute distress immediately following an ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scan is an exceedingly rare event. We report a case whose condition was suddenly deteriorated in the nuclear medicine laboratory, and whose diagnosis was confirmed by FDG-PET/CT. A 67-year-old woman with left renal cell carcinoma (RCC) suddenly complained of dyspnea and tachycardia just after undergoing FDG-PET/CT. PET/CT images showed increased FDG uptakes in the left renal vein, inferior vena cava, right atrium, and bilateral hila. She was diagnosed with a massive tumor embolism from the inferior vena cava to both pulmonary arteries, and urgently underwent tumor embolectomy. FDG-PET/CT was helpful for diagnosing the tumor embolism and differentiating it from bland thromboembolism in this patient with RCC.

Keywords: 18F-fluorodeoxyglucose positron emission tomography/computed tomography; CD, cluster of differentiation; CECT, contrast-enhanced computed tomography; FDG-PET/CT, 18F-fluorodeoxyglucose positron emission tomography/computed tomography; IHC, immunohistochemical; IVC, inferior vena cava; Pulmonary tumor embolism; RCC, renal cell carcinoma; Renal cell carcinoma; SUVmax, maximum standardized uptake value; TFE3, transcription factor E3; TTF, thyroid transcription factor.

Several BRAF-driven cancers, including advanced BRAF^V600E/K-driven melanoma, non-small-cell lung carcinoma, and thyroid cancer, are currently treated using first-line inhibitor combinations of BRAF^V600E plus MEK1/2. However, despite the success of this vertical inhibition strategy, the durability of patient response is often limited by the phenomenon of primary or acquired drug resistance. It has recently been shown that autophagy, a conserved cellular recycling process, is increased in BRAF-driven melanoma upon inhibition of BRAF^V600E signaling. Autophagy is believed to promote tumor progression of established tumors and also to protect cancer cells from the cytotoxic effects of chemotherapy. To this end, BRAF inhibitor (BRAFi)-resistant cells often display increased autophagy compared to responsive lines. Several mechanisms have been proposed for BRAFi-induced autophagy, such as activation of the endoplasmic reticulum (ER) stress gatekeeper GRP78, AMP-activated protein kinase, and transcriptional regulation of the autophagy regulating transcription factors TFEB and TFE3 via ERK1/2 or mTOR inhibition. This review describes the relationship between BRAF-targeted therapy and autophagy regulation, and discusses possible future treatment strategies of combined inhibition of oncogenic signaling plus autophagy for BRAF-driven cancers.

Keywords: BRAF; MEK1/2; autophagy; drug resistance; metabolism; targeted therapy.

Perivascular epithelioid cell tumors (PEComas) are infrequent mesenchymal neoplasms that have particular histological and immunohistochemical features. Only a few cases have been described in the eye and orbit. This report presents a 28-year-old man who consulted for a painless left orbital mass. With the presumptive diagnosis of cavernous hemangioma, a surgical excisional biopsy was performed. Histopathological examination showed a well-delimited tumor composed of epithelioid cells with an eosinophilic cytoplasm and oval nucleus. The tumor cells stained diffusely for HMB-45 and transcription factor E3 (TFE3) and were focally positive for actin. There was no reactivity to S100 or desmin. Genetic testing revealed a TFE3 rearrangement. Based on these results, an extremely rare orbital TFE3-rearranged PEComa was diagnosed. Although no recurrence was seen at last follow-up, a review of the literature shows experience is limited regarding orbital PEComas and their malignant potential. Further research is needed to establish management guidelines, their association with the tuberous sclerosis complex, and the role of genetic mutations such as TFE3 rearrangement.

Epithelioid hemangioendothelioma is a rare malignant vascular neoplasm caused by the proliferation of neoplastic endothelial cells. Epithelioid hemangioendothelioma may develop in any organ, but it is commonly observed in the extremities. The tongue is a very unusual location for epithelioid hemangioendothelioma. A 55-year-old male patient presented to the outpatient head and neck clinic with lumps in the tongue, pain, and limitation of motion. The polypoid mass detected in the anterior midline of the tongue was excised. Microscopically, the tumor cells included slightly pleomorphic oval or round vesicular nuclei with an eosinophilic cytoplasm that variably contained vacuoles. There were 4 mitoses per 10 high power fields and there was no necrosis. In immunohistochemical study, the tumor cells were positively stained with CD31 and CD34 whereas they were negatively stained with TFE3, SMA, S-100, HHV-8 and EMA. The patient was diagnosed with "epitheloid hemangioendothelioma". Only ten cases have been reported in the tongue in the literature. Our case was the eleventh case, and we aimed to report this case as a rare entity with an unusual location.

Background: Xp11.2 translocation renal cell carcinoma (tRCC) is defined by translocation of the transcription factor E3 (TFE3) gene located on chromosome Xp11.2. Due to the high incidence in women, 17β-estradiol (E2) may be a factor influencing TFE3 breaks, and the topoisomerase II (TOP2) poison is considered one of the important risk factors in mediating DNA breaks. In this study, we investigated the potential pathogenesis of Xp11.2 tRCC using the renal epithelial cell line HK-2.

Methods: Immunofluorescence assay was performed to analyze DNA breaks by quantifying phosphorylation of H2AX (γH2AX), and the micronuclei (MN) assay was designed for monitoring chromosome breaks. The chromatin immunoprecipitation (CHIP) was used to detect whether proteins bound to specific DNA site, and the co-immunoprecipitation (Co-IP) was used to confirm whether proteins bound to other proteins. In some experiments, siRNA and shRNA were transfected to knockdown target genes.

Results: Our results demonstrated that DNA double-strand breaks were mediated by TOP2β in HK-2 cells, and this process could be amplified through estrogen receptor α (ERα)-dependent pathway induced by E2. After performing translocation site analysis using target region sequencing data in two Xp11.2 tRCC cell lines and ten Xp11.2 tRCC patients, we confirmed that TOP2β and ERα could both bind to TFE3 translocation sites directly to mediate DNA breaks in a E2-dependent manner. However, TOP2β and ERα were not observed to have direct interaction, indicating that their collaborative may be implemented in other ways. Besides, TFE3 was found to be upregulated through NRF1 with increasing E2 concentration, which could increase the risk of TFE3 breaks.

Conclusion: Our results indicate that E2 amplifies TOP2β-mediated TFE3 breaks by ERα-dependent pathway, and E2 upregulates TFE3 by NRF1 to increase the risk of TFE3 breaks. This suggests that E2 is an important pathogenic factor for Xp11.2 tRCC pathogenesis. Video Abstract.

Keywords: Estradiol; Estrogen receptor; Renal cell carcinoma; TFE3; Topoisomerase; Xp11.2.

Objective: To study the clinicopathologic, immunohistochemical (IHC), histogenetic and prognostic features of acquired cystic kidney disease-associated renal cell carcinoma (ACKD-RCC). Methods: Three cases of ACKD-RCC, including two from 401 Hospital of PLA and one from the Affiliated Hospital of Qingdao University were studied by clinical, histological and IHC analysis with review of relevant literature. Results: All the three patients were male, ranging from 46 to 78 years old. All patients had history of chronic renal failure; two patients were treated with hemodialysis for 9 years and 11 years, respectively. In two cases the tumor sizes were 2.5 cm and 3.5 cm, respectively, and the tumor border was distinct. The remaining case showed extensive renal hemorrhage with an inconspicuous mass. Microscopically, the tumor cells were arranged in cribriform, microcystic or acinar structures, with variable papillary structure in one case. Hemorrhage of varying degrees was seen in all three cases, and obvious necrosis was noted in two. The tumor cells had deeply eosinophilic cytoplasm, indistinct cell border, round or oval nuclei, and prominent nucleoli (WHO/ISUP grade 3). Mitoses were rare. Abundant oxalate crystals were seen in two cases. The renal mesenchyme of all three cases were atrophic with variable cystic changes of the renal tubules, the lining cells showed atypical hyperplasia. IHC staining showed all tumors were diffusely positive for vimentin, CD10, RCC, CAM5.2, P504s and mitochondria in the cytoplasm, and were variably positive for EMA (2/3), CK7 (1/3), CA9 (1/3) and PAX8 (3/3). All cases were negative for CD117, HMB45, Melan A and TFE3. After 3-14 months follow-up, one patient died from renal failure six months after surgery. The other two patients were alive without tumor recurrence or metastasis. Conclusions: ACKD-RCC is a very rare renal cell carcinoma. The specific cribriform structure, deeply eosinophilic cytoplasm, prominent nucleoli (WHO/ISUP grade 3), and oxalate crystals deposition, associated with the history of ACKD could aid the diagnosis. ACKD-RCC arises from the proximal renal tubule and its histogenesis might be associated with proliferation and malignant change of the atypical epithelial cells of the cystic renal tubules. ACKD-RCC may have a favorable prognosis except for tumors with sarcomatoid differentiation.

Objective: To investigate the clinicopathological manifestations, molecular genetic, diagnostic histology and differential diagnosis of alveolar soft part sarcoma (ASPS) in children. Methods: A total of 13 cases of ASPS diagnosed at Beijing Children's Hospital from August 2009 to November 2018 were collected. HE staining, histochemical staining for PAS and D-PAS, immunohistochemical (IHC) staining for TFE3, INI1 and CD68 and florescence in situ hybridization (FISH) for TFE3 gene translocation were performed. Results: There were four males and nine females, age ranged from 1 year and 2 months to 13 years and 8 months (mean 7.8 years); and four patients were under 5 years old. Histologically, the tumors showed a distinctive and characteristic nested or organoid growth pattern (11 cases) or solid, diffuse growth (2 cases). The tumor cells possessed abundant eosinophilic, or glycogen-rich and clear to vacuolated cytoplasm. The chromatin was relatively dispersed, with prominent and pleomorphic nucleoli; mitotic figures were rare. Vascular invasion was frequently seen. IHC staining showed specific nuclear TFE3 staining. The tumor cells were also positive for INI1,CD68 and vimentin; but were negative for MyoD1, Myogenin, CK and S-100 protein. Seven cases showed PAS and D-PAS staining, with fuchsia acicular or rod-shaped crystals in tumor cytoplasm. Nine cases showed TFE3 break-apart signals by FISH. Conclusions: ASPS is a rare soft tissue sarcoma in children. Compared with ASPA in adults, it has both similarities and unique clinicopathologic characteristics. The diagnosis needs to be confirmed by combining clinical, pathologic, IHC and genetic testing.

Macroautophagy/autophagy induction by caloric restriction mimetics (CRMs) is a strategy to stimulate anticancer immune responses of immunogenic cell death (ICD)-inducing chemotherapeutics. We designed a phenotypic screening campaign in which we identified pharmacological agents that have CRM properties (i.e., non-cytotoxic induction of autophagic flux that reduces cytoplasmic protein acetylation) and simultaneously act as ICD amplifiers (i.e. with the capacity to enhance the release of adenosine triphosphate, ATP, from stressed and dying cancer cells). This approach led to the identification of thiostrepton, a natural cyclic oligopeptide antibiotic, as an agent that enhances chemotherapy-induced anticancer immune responses in vivo, in immunocompetent mice bearing syngeneic tumors. Interestingly, both the pro-autophagic and the anticancer effects of thiostrepton rely on the activation of TFEB (transcription factor EB) and TFE3 (transcription factor E3). In summary, thiostrepton represents a novel CRM and ICD amplifier that may be useful for cancer therapy.

Alveolar soft-part sarcoma is a mesenchymal malignancy characterized by the rearrangement of ASPSCR1 and TFE3 and a histologically distinctive pseudoalveolar pattern. Although alveolar soft-part sarcoma takes an indolent course, its long-term prognosis is poor because of late distant metastases. Currently, curative treatments have not been found for alveolar soft-part sarcoma, and hence, a novel therapeutic strategy has long been required. Patient-derived cell lines comprise an important tool for basic and preclinical research. However, few cell lines from alveolar soft-part sarcoma have been reported in the literature because it is an extremely rare malignancy, accounting for less than 1% of all soft-tissue sarcomas. This study aimed to establish a novel alveolar soft-part sarcoma cell line. Using surgically-resected tumor tissue of alveolar soft-part sarcoma, we successfully established a cell line and named it NCC-ASPS1-C1. The NCC-ASPS1-C1 cells harbored an ASPSCR1-TFE3 fusion gene and exhibited slow growth, and spheroid formation. On the other hand, NCC-ASPS1-C1 did not show the capability of invasion. We screened the antiproliferative effects of 195 anticancer agents, including Food and Drug Administration-approved anticancer drugs. We found that the MET inhibitor tivantinib and multi-kinase inhibitor orantinib inhibited the proliferation of NCC-ASPS1-C1 cells. The clinical utility and molecular mechanisms of antitumor effects of these drugs are worth investigating in the further studies, and NCC-ASPS1-C1 cells will be a useful tool for the in vitro study of alveolar soft-part sarcoma.

Keywords: Alveolar soft-part sarcoma; Cell line; Orantinib; Patient-derived cancer model.

The genetics of renal tumors in children is widely recognized. However, most of the studies published to date emphasize the association between Wilms tumor and the WT-1 gene. Recently, a unique translocation between the X chromosome and chromosome 1 or t(X;1) has been described in several reports of renal cell carcinomas (RCCs) diagnosed in children and adolescents that results in PRCC-TFE3 gene fusion. We report here a 9-year old African-American boy with a history of a right congenital mesoblastic nephroma treated with nephrectomy and followed by annual checkups. After 9 years, he was diagnosed with a mass at the hilum of the left kidney during the work-up of new-onset hypertension. A limited biopsy revealed densely hyalinized connective tissue that was initially interpreted to be a hyalinized contralateral mesoblastic nephroma. The child received chemotherapy, but the mass continued to grow. He underwent a left nephrectomy, and the pathology was diagnostic for a clear cell RCC. Chromosomal analysis disclosed a t(X;1)(p11.2;q21) translocation, which is known to result in a PRCC-TFE3 gene fusion. The tumor showed nuclear labeling for TFE3 protein by immunohistochemistry, supporting the above diagnosis. He has been on hemodialysis, is tumor free, and has not been receiving chemotherapy for 24 months. This is the first report of a RCC as a second malignant neoplasm in a child treated for a congenital mesoblastic nephroma.

Macrophage activation in the presence of bacterial cells and molecules entails complex programs of gene expression. How such triggers elicit specific gene expression programs is incompletely understood. We previously discovered that TFEB (transcription factor EB) is a key contributor to macrophage activation during bacterial phagocytosis. However, the mechanism linking phagocytosis of bacterial cells to TFEB activation and downstream pro-inflammatory cytokine induction remained unknown. We found that macrophages lacking both TFEB and TFE3 (transcription factor E3) were unable to mount a pro-inflammatory phenotype in response to bacterial infection. The NOX/PHOX (NADPH oxidase)-dependent oxidative burst was required for nuclear translocation of TFEB during phagocytosis of Gram-positive or -negative bacteria, and reactive oxygen species (ROS) were sufficient to trigger TFEB activation in a CD38- and NAADP (nicotinic acid adenine dinucleotide phosphate)-dependent manner. Consistent with the Ca²⁺-releasing activity of NAADP, intracellular Ca²⁺ chelation and PPP3/calcineurin inhibition prevented TFEB activation by phagocytosis and ROS (reactive oxygen species), impairing the induction of pro-inflammatory cytokines such as IL6 and TNF/TNFα. Therefore, here we describe a previously unknown pathway that links phagocytosis with macrophage pro-inflammatory polarization via TFEB and related transcription factor TFE3. These findings reveal that activation of TFEB and TFE3 is a key regulatory event for the activation of macrophages, and have important implications for infections, inflammation, cancer, obesity, and atherosclerosis.

Keywords: CD38; il1α; il1β; il6; innate immunity; phagocyte; reactive oxygen species; tfe3; tfeb; tnfα.

Microphthalmia-associated transcription factor (MiT) family aberration-associated renal cell carcinoma (MiTF-RCC) is a subtype of renal cell carcinoma harboring recurrent chromosomal rearrangements involving TFE3 or TFEB genes. MiTF-RCC is morphologically diverse, can histologically resemble common RCC subtypes like clear cell RCC and papillary RCC, and often poses a diagnostic challenge in genitourinary clinical and pathology practice. To characterize the MiTF-RCC at the molecular level and identify biomarker signatures associated with MiTF-RCC, we analyzed RNAseq data from MiTF-RCC, other RCC subtypes and benign kidney. Upon identifying TRIM63 as a cancer-specific biomarker in MiTF-RCC, we evaluated its expression independently by RNA in situ hybridization (RNA-ISH) in whole tissue sections from 177 RCC cases. We specifically included 31 cytogenetically confirmed MiTF-RCC cases and 70 RCC cases suspicious for MiTF-RCC in terms of clinical and morphological features, to evaluate and compare TRIM63 RNA-ISH results with the results from TFE3/TFEB fluorescence in situ hybridization (FISH), which is the current clinical standard. We confirmed that TRIM63 mRNA was highly expressed in all classes of MiTF-RCC compared to other renal tumor categories, where it was mostly absent to low. While the TRIM63 RNA-ISH and TFE3/TFEB FISH results were largely concordant, importantly, TRIM63 RNA-ISH was strongly positive in TFE3 FISH false-negative cases with RBM10-TFE3 inversion. In conclusion, TRIM63 can serve as a diagnostic marker to distinguish MiTF-RCC from other renal tumor subtypes with overlapping morphology. We suggest a combination of TFE3/TFEB FISH and TRIM63 RNA-ISH assays to improve the accuracy and efficiency of MiTF-RCC diagnosis. Accurate diagnosis of MiTF-RCC and other RCC subtypes would enable effective targeted therapy and avoid poor therapeutic response due to tumor misclassification.

The patient was a 33-year-old female who visited the Department of Gastroenterology of this hospital after experiencing lower abdominal pain and nausea. The patient was referred to this department after suspicions of right kidney hemorrhage revealed by non-contrast computed tomography (CT). We also identified hematuria macroscopically, and contrast-enhanced CT scans revealed uneven deep staining in the upper right kidney during the early phase. Furthermore, by the late phase, we identified a 29-mm solid tumor with no staining. There was no clear pseudomembrane and no clear boundary with the kidney parenchyma. Additionally, there was no metastasis to the lymph nodes and other organs. Based on the above findings, we suspected renal parenchymal infiltration of right renal cell carcinoma (RCC) or right renal pelvic carcinoma. Since the patient was young, we considered the risk of the residual tumor and performed total nephroureterectomy and lymph node dissection with an enlarged view. The inside of the resected tumor specimen showed significant necrosis and hematoma spread, which had infiltrated the renal pelvis. Based on the characteristic histological findings and genetic results obtained using the fluorescence in situ hybridization (FISH) approach, we diagnosed the patient with Xp11.2 translocation RCC. No additional treatments were provided after surgery, and even now the patient is being followed-up through outpatient visits, but there has been no recurrence or new metastasis. There have only been a few reported cases of Xp11.2 translocation RCC; therefore, in many cases, treatments and follow-up duration according to the disease stage and disease prognosis have not been determined. In this study, we report a case of Xp11.2 translocation RCC experienced at our hospital, with additional literature considerations.

Keywords: TFE3; Xp11.2 translocation renal cell carcinoma; renal cell carcinoma.

Objective: To report the exceptional occurrence of ossifying fibromyxoid tumour (OFMT) as a primary bone lesion. OFMT is a rare soft tissue tumour of uncertain differentiation and variable malignant potential, that occurs in adults with a slight male predominance. It is typically located in the subcutis or in the skeletal muscles of the extremities, followed by trunk or head and neck.

Methods: Two cases of OFMT proven to arise from bone are presented. The first is a 65-year old female with a history of rib "osteosarcoma", presenting with an inferior lobe left lung mass. The second is a man with a lytic lesion of the 5th cervical vertebra that recurred shortly after resection. Following H&E and immunohistochemical examination, tumour samples were analysed by NGS and by break-apart FISH to detect rearrangement of the PHF1 and TFE3 genes.

Results: PHF1 gene-rearrangement was identified by FISH on both the primary and the metastatic lesion of first patient. NGS identified a PHF1(intron1) and EPC1 (exon 10) fusion transcript later confirmed by positive PHF1 rearrangement on FISH in the second case.

Conclusions: The demonstration of PHF1 gene rearrangements represents a fundamental ancillary diagnostic test when presented with challenging examples of OFMT.

Keywords: OFMT; PHF1; bone tumours; rare tumours; soft tissue tumours.

Context.—: Bone and soft tissue tumors are heterogeneous, diagnostically challenging, and often defined by gene fusions.

Objective.—: To present our experience using a custom 34-gene targeted sequencing fusion panel.

Design.—: Total nucleic acid extracted from formalin-fixed, paraffin-embedded (FFPE) tumor specimens was subjected to open-ended, nested anchored multiplex polymerase chain reaction and enrichment of 34 gene targets, thus enabling detection of known and novel fusion partners.

Results.—: During a 12-month period, 145 patients were tested as part of routine clinical care. Tumor percentage ranged from 10% to 100% and turnaround time ranged from 3 to 15 (median, 7.9) days. The most common diagnostic groups were small round blue cell tumors, tumors of uncertain differentiation, fibroblastic/myofibroblastic tumors, and adipocytic tumors. In-frame fusion transcripts were identified in 64 of 140 cases sequenced (46%): in 62 cases, the detection of a disease-defining fusion confirmed the morphologic impression; in 2 cases, a germline TFG-GPR128 polymorphic fusion variant was detected. Several genes in the panel partnered with multiple fusion partners specific for different diagnoses, for example, EWSR1, NR4A3, FUS, NCOA2, and TFE3. Interesting examples are presented to highlight how fusion detection or lack thereof was instrumental in establishing accurate diagnoses. Novel fusion partners were detected for 2 cases of solid aneurysmal bone cysts (PTBP1-USP6, SLC38A2-USP6).

Conclusions.—: Multiplex detection of fusions in total nucleic acid purified from FFPE specimens facilitates diagnosis of bone and soft tissue tumors. This technology is particularly useful for morphologically challenging entities and in the absence of prior knowledge of fusion partners, and has the potential to discover novel fusion partners.

Objective: To investigate the clinicopathological features, differential diagnosis and molecular characteristics of clear cell renal cell carcinoma (ccRCC) with hemangioblastoma component (ccRCC-HBc). Methods: Two ccRCC-HBc cases diagnosed at Fujian Provincial Hospital in September 2015 and March 2016, respectively, were included. Their morphological, immunohistochemical and molecular features were analyzed, including fluorescence in situ hybridization (FISH) detection of TFE3, TFEB and VHL genes. Related literature was reviewed to reveal the characteristics of this tumor. Results: The two cases occurred in 2 women, aged 33 and 66 years, respectively. The maximum diameters of the tumors were 4.0 cm and 8.5 cm, respectively. Histologically, the ccRCC component, representing approximate 10%-20% of the neoplasm, while the tumor cells arranged in flaky, nested, and solid distribution. The tumor cells had conspicuous nucleoli, with rich thin-wall capillary network in the stroma. The hemangioblastoma-like component, representing approximate 60%-70% of the neoplasm, showed a rich capillary network of single-layered flat endothelial cells enclosing stromal cells. The latter cell type showed a pale or eosinophilic cytoplasm exhibiting occasional lipid droplets. Rare cell nuclei appeared enlarged, pleomorphic, or bizarre. The two components were intermingled with each other. Immunohistochemically, the tumor cells were positive for PAX8, CKpan, EMA, vimentin, CD10, RCC, CAⅨ, and P504s in ccRCC area; in another area, the tumor cells were positive for α-inhibin, CD34 and vimentin, while CD10 were weakly positive. Neither TFE3 or TFEB gene split signal was detected in the 2 cases (0/2), nor was VHL gene mutation in case 2 (0/1). Conclusion: ccRCC-HBc is an extremely rare entity of ccRCC. The diagnosis is mainly based on clinical and pathological characteristics, as well as immunohistochemistry. Molecular pathology is helpful for its differential diagnosis. The primary approach of treating ccRCC-HBc is complete surgical excision and chemotherapy. The targeted treatment is helpful if possible.

目的： 探讨伴血管母细胞瘤成分肾透明细胞癌［clear cell renal cell carcinoma （ccRCC） with hemangioblastoma（HB） component， ccRCC-HBc］的临床病理及分子学特征。 方法： 收集2015年9月和2016年3月福建省立医院手术切除标本及会诊病例共2例ccRCC-HBc，进行HE、免疫组织化学染色，荧光原位杂交（FISH）检测TFE3、TFEB及VHL基因，并进行文献复习。 结果： 2例女性，年龄分别为33和66岁，肿块大小4.0 cm和8.5 cm。病理组织学上2例肿瘤可见明确ccRCC区域，部分区呈血管母细胞瘤（HB）样表现，见增生的毛细血管，细胞多变，胞质透明、空泡样，两种成分相互移行。免疫表型上，ccRCC区瘤细胞呈PAX8、广谱细胞角蛋白（CKpan）、上皮细胞膜抗原（EMA）、波形蛋白、CD10、肾细胞癌标志物（RCC）、碳酸酐酶Ⅸ（CAⅨ）、P504s阳性；HB样区域α抑制素、CD34、波形蛋白阳性，CD10弱阳性。FISH均未检测到TFE3、TFEB基因分离信号（0/2），例2未检测到VHL基因突变（0/1）。 结论： ccRCC-HBc属于ccRCC一种罕见的变异亚型，确诊依靠临床病理学、免疫组织化学，必要时行分子病理检测有助鉴别。治疗以手术切除为主，并辅以化疗，必要时行靶向治疗。.

目的： 探讨肠道血管周上皮样细胞肿瘤（PEComa）的临床病理学特征。 方法： 收集3例肠道PEComa病例的资料，光镜下观察HE、免疫组织化学和特殊染色切片，应用荧光原位杂交（FISH）法检测TFE3基因断裂重组情况，复习相关文献并进行分析总结。 结果： 肿瘤主要位于肠道黏膜下层和肌层，界限较清，细胞呈上皮样或胖梭形，2例排列成实性片状或巢状，1例排列成显著的腺泡状，部分肿瘤细胞围绕厚壁血管向外周呈放射状排列。灶性肿瘤细胞显示异型性，未见坏死，核分裂象罕见。肿瘤组织不同程度表达平滑肌及黑色素源性免疫标志物，其中1例肿瘤组织表达TFE3并经FISH检测证实有TFE3基因断裂重组。 结论： 发生于肠道的PEComa罕见，需与多种肿瘤鉴别，认识到它的存在、熟悉其特征可避免误诊。.

伴有高级别转化的胰腺实性假乳头状肿瘤相对罕见，该文报道1例33岁的女性病例，显微镜下肿瘤由囊性区、假乳头区和实性区构成，实性区可见大片出血坏死，假乳头区可见松散的上皮样细胞包绕纤维血管轴心，肿瘤细胞呈圆形和卵圆形，胞质丰富嗜酸性，核圆形，部分细胞异型性明显，并可见瘤巨细胞；免疫表型：肿瘤细胞转录因子E3（TFE3）阳性、β-catenin胞质阳性，极少数胞膜不连续性阳性，未见核阳性表达。该例形态学及免疫表型不典型，易误诊为胰腺神经内分泌肿瘤。该文描述其组织学特点、免疫表型，阐述其诊断要点，并复习和总结相关文献。.

BACKGROUND

Alveolar soft part sarcoma (ASPS) is a rare, malignant soft-tissue neoplasm typically seen in young adults that possesses an unusual tendency to metastasize. Metastases to the intramedullary compartment of the spinal cord, however, are exceptionally rare and have not been described in the literature.

METHODS

We report the case of a 23-year-old woman with disseminated ASPS to the lung and brain who presented with progressive lower-extremity weakness and loss of sensation after radiation and chemotherapy. Magnetic resonance imaging revealed a 1.3-cm avidly enhancing lesion within the central thoracic spinal cord at T3. A T2-T4 laminectomy was undertaken and resulted in a gross total resection. Histopathologically, the mass was composed of organoid nests containing epithelioid cells with eosinophilic, granular cytoplasm separated by sinusoidal spaces. Immunohistochemistry demonstrated convincing positive TFE3 staining. Postoperative imaging confirmed the complete resection of the mass, and her examination was notable for intact sensation and impaired motor function that gradually improved.

CONCLUSIONS

A review of the literature found that the reported case represents the first instance of primary or metastatic ASPS in the spinal cord. Metastatic ASPS should thus be included in the differential diagnosis in patients with known disease and neurologic impairment or back pain. Imaging of the spine should then be considered.

Alveolar soft part sarcoma (ASPS) is a rare malignancy that, since its initial description, remains a neoplasm of uncertain histogenesis. The disease-defining molecular event characterizing the diagnosis of ASPS is the ASPSCR1-TFE3 fusion gene. Following identification of an index case of ASPS with a novel TFE3 fusion partner, we performed a retrospective review to determine whether this represents an isolated event. We identified two additional cases, for a total of three cases lacking ASPSCR1 partners. The average patient age was 46 years (range, 17-65); two patients were female. The sites of origin included the transverse colon, foot, and dura. Each case exhibited a histomorphology typical of ASPS, and immunohistochemistry was positive for TFE3 in all cases. Routine molecular testing of the index patient demonstrated a HNRNPH3-TFE3 gene fusion; the remaining cases were found to have DVL2-TFE3 or PRCC-TFE3 fusion products. The latter two fusions have previously been identified in renal cell carcinoma; to our knowledge, this is the first report of a HNRNPH3-TFE3 gene fusion. These findings highlight a heretofore underrecognized genetic diversity in ASPS, which appears to more broadly molecularly overlap with that of translocation-associated renal cell carcinoma and PEComa. These results have immediate implications in the diagnosis of ASPS since assays reliant upon ASPSCR1 may yield a false negative result. While these findings further understanding of the molecular pathogenesis of ASPS, issues related to the histogenesis of this unusual neoplasm remain unresolved.