Myxoid Liposarcoma of the Supraclavicular Fossa^* FREE TO VIEW

Liposarcoma , the second most common soft-tissue sarcoma in adults, is separable into the following five major morphologic subtypes: well-differentiated, myxoid, round cell, dedifferentiated, and pleomorphic.¹ The myxoid variant, which is characterized by the chromosomal translocation t(12;16) (q13;p11), is a lobulated soft-tissue tumor composed of slender, hyperchromatic spindle cells and signet-ring lipoblasts, a plexiform vascular pattern, and a myxoid matrix.¹ Liposarcomas occur most often in the extremities and retroperitoneum, with only 5% occurring in the head and neck and 3% occurring in the thorax (primarily the mediastinum).¹ Recently, we treated a patient with a myxoid liposarcoma that arose in a rarely described site, the supraclavicular fossa, and have reviewed our pathology database and the literature for similar cases.

A 71-year-old man presented with a history of several months of an enlarging, painless left supraclavicular fossa mass, measuring 7 cm. As a child, he underwent complete resection of a benign mass from his thigh. An excisional biopsy performed in March 1998 demonstrated a lobulated tumor, 5 cm in size, not arising from a lymph node. A histologic section (Fig 1 ) showed spindle-shaped cells and signet-ring lipoblasts in a myxoid matrix, which is consistent with myxoid liposarcoma. The surgical margins were involved with tumor, although no residual tumor was found at repeat resection. Postoperative staging studies demonstrated no residual mass in the supraclavicular fossa and no metastases in the remainder of the chest, abdomen, or bones. No adjuvant therapy has been given, and the patient has been observed without evidence of recurrence.

We searched our pathology database for biopsy specimens that were coded as being soft-tissue tumors and arising in the supraclavicular fossa, and we reviewed the available cases for which the final diagnosis was a soft-tissue sarcoma to identify other cases of liposarcomas. We found 19 other supraclavicular soft-tissue tumors that were not breast or lung cancer, lymphoma, adenocarcinoma of unknown primary origin, melanoma, or metastases from other known primary sites. The soft tissue-tumors were divided as follows: 13 lipomas; 1 lymph node metastasis of malignant fibrous histiocytoma originating in the scalp; 1 fibrosarcoma arising in the subclavian region in a patient who had undergone, as a neonate, resection of a hemangioendothelioma near the upper thoracic spine; 1 epithelioid hemangioendothelioma arising in the mediastinum and progressing locally into the subclavian region; 1 round-cell liposarcoma that occurred concurrently with a similar lesion in the liver and represented a metastasis from a primary calf tumor diagnosed 1 year previously; and 2 undifferentiated sarcomas that lacked clinical data.

A MEDLINE search was performed for supraclavicular, thoracic, or head and neck sarcomas to identify similar cases. Reports of supraclavicular sarcomas are indeed uncommon, compared with the more frequent finding of lipomas, which accounted for 13 of 20 mesenchymal masses resected from the supraclavicular fossa at our institution. Only two other reports (with four patients total) detailing the supraclavicular fossa as a primary site for liposarcomas have been published. Kindblom et al² described one case each of well-differentiated round-cell liposarcoma and pleomorphic liposarcoma. All patients had recurrences requiring repeat resections or radiation therapy, and the patient with a pleomorphic liposarcoma died of multiple pulmonary metastases. Minic³ described a case of well-differentiated liposarcoma in the supraclavicular fossa that recurred despite resection and radiation therapy. In reviews of adult patients with a total of 1,305 head and neck soft-tissue sarcomas,⁴ only 30 patients (2%) had neck liposarcomas, although the exact location usually was not specified. Reviews of reports of thoracic liposarcomas demonstrate that most originate in the chest wall, mediastinum,⁵ or pleura, with no reports of a supraclavicular location. Myxoid liposarcoma is also notable for metastasizing to unusual sites, including the serosal surfaces of the pleura, mediastinum, pericardium, and diaphragm, and to extrapulmonary soft-tissue sites, including the peritoneum, chest wall, and breast. Lymph node metastases are extremely rare. We do not believe that our patient had a metastasis, although he had an unspecified tumor in his leg as a child 50 to 60 years earlier and recurrences after 30 years have been reported.¹

The prognosis for our patient is excellent. Factors that predict a better prognosis for liposarcomas are a well-differentiated and myxoid histology, a low percentage of the round-cell component, no spontaneous necrosis, a low number of mitoses, a size < 5 cm, and age< 45 years.⁶ Studies evaluating marginal status as a prognostic factor have found up to 100% survival for free margins. Nonetheless, some investigators have argued for the delivery of adjuvant postoperative radiation therapy and have achieved control rates of > 90% after 10 years.⁶ These contrary opinions likely reflect the ability to achieve generous surgical margins. The role of chemotherapy is uncertain.