Metastasis of Dermatofibrosarcoma from the Abdominal Wall to the Thyroid Gland: Case Report

1. Introduction

Thyroid gland tumors account for 0.5–1% of all malignancies [1]. According to the World Health Organisation (WHO) primary thyroid tumors are classified as epithelial and nonepithelial, benign or malignant, with a separate category for lymphomas and miscellaneous neoplasms [2]. Classification according to the Armed Forces Institute of Pathology (AFIP) gives priority to the cell of origin and incorporates, in each cell type, special tumor types andsubtypes designated as “variants” [3]. Sarcomas according to WHO classification are class V, while for AFIP classification they are A4.

Dermatofibrosarcoma protuberans (DFSP) is arather uncommon soft tissue tumor of mesenchymal origin arising in the dermis. It is regarded as having intermediate malignant potential. DFSP accounts for less than 2% of all soft-tissue sarcomas (less than 0.1% of all cancers). The most common location is the trunk (50%), proximal extremities (30%), head and neck (0%–15%), and rare cases involving the hands and feet. The usual presentation is an asymptomatic firm plaque that may be red, brown, violaceous, or flesh colored. Lesion size ranges from 1 to 5 cm [4]. Histological evaluations show a dense array of spindle-shaped tumor cells, slender nuclei, intracellular collagen deposition, and small capillary blood vessels throughout. Metastasis is quite unusual [4], the majority of soft tissue sarcomas metastasize to the lungs. Less frequently reported sites include the retroperitoneum, mediastinum, bones, and rarely the kidney, brain, omentum, scalp, ovaries, liver, and heart [5]. The first case of DFSP metastasis to the thyroid gland was described by Onoda in 1990 [6].

Solitary thyroid nodules are common in clinical practice but nodular intrathyroid metastasis is rare and may be underestimated [7].

The prevalence of intrathyroid metastases of nonthyroid origin ranges from 1.9% to 25% [8].

Direct extension into the thyroid may occur in carcinomas of the pharynx, larynx, trachea, and esophagus. Retrograde lymphatic spread into the thyroid has been reported with breast carcinoma as well as hematogeneous metastases to the thyroid, particularly of malignant melanoma, lung, gastrointestinal, breast, and renal cell carcinomas. Rare sources of primary tumors are choriocarcinoma, malignant phylloides tumors, and sarcoma [1].

2. Case Report

A 52-year-old woman with a personal history including several surgeries: an appendectomy long ago, extirpation of dermatofibrosarcoma of the inguinal suprapubic region on the left side in1998, and surgically treated recurrences in 2000, 2001, 2008, and 2009. The last lesion was as large as 8 × 4 cm. Histological findings were fusiforme and mitotic activity. After last surgical treatment was done local external radiotherapy (66 Gy).

In 2011 she consulted our endocrinology department following the discovery of recent swelling on the right side on her neck, concomitant with worsened swallowing, and mild pain. The thyroid nodule appeared 13 years after diagnosis of sarcoma of the abdominal wall.

Initial physical finding was on the neck palpable large, prominent, markedly firm, mildly painful resistance on right side, no fixation. Pemberton sign positive.

3. Discussion

The thyroid gland is known but unusual site for metastases from sarcomas. There are 10 known cases of leiomyosarcoma metastases to the thyroid, 5 are from primary uterine leyomyosarcoma [22], while there is one case each of metastasis from histiosarcoma of the ankle [23], histiosarcoma of the thigh [24], carciosarcoma [25], liposarcoma of the thigh [26], leiomyosarcoma of the duodenum [27], and leiomyosarcoma of the leg [28]. Other possible and described metastases to the thyroid gland are shown in Table 1.

Clinically, patients tend to be in the their sixth decade of life or older, usually have a mass on the neck, along with dysphagia, hoarseness, and cold intolerance [23].

Diagnosis of a thyroid nodule as ametastatic lesion is not possible based on clinical and radiological grounds. FNAB is an easy, simple, and useful procedure.

Debulking or thyroidectomy is often indicated to confirm diagnosis and to alleviate any symptoms of neck compression [24].

After surgical management, the administration of systemic therapy is recommended [8].

The prognosis of these patients is grave, although surgical treatment prolongs the time of life (average 34 months with surgery versus 24 without) [12].

This case of dermatofibrosarcoma of the abdominal wall spreading to the thyroid gland is quite rare.

4. Conclusion

Metastasis should be considered in any patient with a previous history of malignancy and a new thyroid mass. Diagnosis is possible with FNAB and definitive after surgical treatment with histology. Chemo- and/or radiotherapy may be administered following surgery with various results. In some cases dermatofibrosarcoma protuberans may also be adequately treated with imatinib.