Primary sclerosing epithelioid fibrosarcoma of the lung in a patient with Lynch syndrome.

Sclerosing epithelioid fibrosarcoma (SEF) is a rare neoplasm arising mostly in limbs and limb girdles, with a high rate of recurrence and a strong tendency to metastasize. This case study is of a 54-year-old woman with an asymptomatic mass in the upper lobe of the left lung detected by PET-CT when staging for Lynch syndrome-associated colon carcinoma. Histology of the resected tumor showed epithelioid cells arranged in nests, partly restiform within a zone of sclerosing fibrosis. Immunohistochemistry was positive for vimentin, epithelial membrane antigen, and S100-protein. Eight months after lung resection, the patient was diagnosed for basal cell carcinoma on her back. At the end of a two year follow-up period, she developed metastases to the mediastinum, vertebrae, ribs, femurs, pelvic bones, kidneys, and one lung, histologically all related to SEF. Here we report the first case of a SEF primarily arising from the lung and discuss it in the context of the current literature.