Abdominopelvic sarcoma of perivascular epithelioid cells. Report of four cases in young women, one with tuberous sclerosis

The perivascular epithelioid cell has been proposed to be the unifying prol iferating cell type in a number of lesions such as angiomyolipoma, lymphang iomyomatosis, clear cell "sugar" tumor and renal capsuloma. With the except ion of rare examples of angiomyolipoma, they are non-metastasizing. We repo rt four examples of a new member of this family of perivascular epithelioid cell neoplasms that occur in abdominopelvic location and show metastatic p roperties. The patients, all women, were aged 19 to 41 years (mean, 32), an d presented with a tumor mass involving the serosa of the ileum, uterus or pelvic cavity. Morphologically, the tumors were composed of sheets of large polygonal cells with glycogen-rich clear or eosinophilic cytoplasm and mod erately pleomorphic nuclei, traversed by a delicate vasculature, mimicking clear cell carcinoma. There were areas of coagulative necrosis and occasion al mitotic figures. Intracytoplasmic brown pigment was present in two cases . Spindly cells, smooth muscle and fat were absent. Lymphovascular invasion was present in all, lymph node metastasis was documented in two and metast asis to the ovary was present in one case. Two patients developed widesprea d metastatic disease after 10 and 28 months from diagnosis. One patient sho wed the clinical signs of tuberous sclerosis. In spite of the epithelial-li ke appearance, the tumor cells were negative for epithelial markers but wer e strongly positive with the melanogenesis-related marker HMB45. Another me lanogenesis marker (MART-1) was positive in two cases. Other markers includ ing S-100 protein, vimentin, muscle-specific actin, desmin and chromogranin A were negative. Thus, these tumors are not readily classifiable in the ex isting schema of known entities, and show over-lapping morpho-phenotypic fe atures of clear cell "sugar" tumor of the lung and epithelioid angiomyolipo ma. We consider them as sarcomas composed of a pure population of uncommitt ed perivascular epithelioid cell, that lack modulation toward smooth muscle or adipose cells.