Perivascular Epithelioid Cell Tumor (PEComa) of the Gynecologic Tract: A Clinicopathologic Analysis of 16 Cases Including TFE3 Rearrangement Analysis in a Subset
John K Schoolmeester, Brooke E Howitt, Michelle S Hirsch, Paola Dal Cin, Bradley J Quade, Marisa R Nucci. Brigham and Women's Hospital, Boston, MA
Background: PEComa is a family of tumors characterized by co-expression of melanocytic and muscle markers. It is often misclassified because it is rare, under-appreciated and has morphologic overlap with epithelioid smooth muscle tumors. This study, the largest to date, characterized the clinicopathologic features of PEComa arising in the female genital tract.
Design: 16 cases of gynecologic PEComa were identified in our institutional and consultation files. All were analyzed for numerous histologic and immunohistochemical features. Staining in >1% of cells was considered positive for all antibodies except TFE3 (>25% staining required). FISH for TFE3 rearrangement was performed in 3 cases. Clinical history and follow up were obtained.
Results: 13 cases were primary of the uterus, 2 of the adnexa and 1 of the vagina. 43.5% of submitting diagnoses were leiomyosarcoma or poorly differentiated uterine sarcoma. Tumors ranged from 0.3 to 15.5 (mean 7.6) cm. 3 patients DOD, 5 are AWD and 8 are AWOD (2 mo-13 yrs follow up, mean 31.2 mo). All patients with adverse outcome had histologic features defining malignancy in non-gynecologic PEComa.
|Tumor Interface (multiple patterns observed)||14 infiltrative, 10 pushing, 3 endometrial stromal sarcoma-like|
|Nested Growth||13/16 (81%)|
|Stromal Hyalinization||9/16 (56%)|
|Tumor Necrosis||8/16 (50%)|
|LV Invasion||5/16 (31%)|
|Cell Morphology||9 predominantly epithelioid (56%), 7 predominantly spindled (44%)|
|Dyscohesive Cells||14/16 (88%)|
|Cytoplasmic Quality||15 clear and eosinophilic (94%), 1 clear vacuolated (6%)|
|Melanoma-like Nucleoli||10/16 (63%)|
|Intranuclear Pseudoinclusions||6/16 (38%)|
|Mitotic Index (per 10 hpf)||Range 0-84 (mean 29)|
|Mitotic Index (per 50 hpf)||Range 0-395 (mean 136)|
|Cathepsin K||12/12 (100%)|