The ultrastructural spectrum of synovial sarcomas: a study of the epithelial type differentiation of primary tumors, recurrences, and metastases.
Synovial sarcomas (SS) are malignant soft tissue tumors of unknown origin. Their classification as carcinomas (monophasic synovial sarcomas, MSS) or carcinosarcomas (biphasic synovial sarcomas, BSS) still raises controversy. In an attempt to settle this controversy, an ultrastructural study was undertaken of 25 primary SS (12 BSS and 13 MSS), 5 recurrences (3 BSS and 2 MSS), and 2 metastases (2 BSS) based upon precise selection of different aspects of BSS and MSS on numerous semithin sections from each case. Ultrastructural markers of epithelial type differentiation of neoplastic cells were found in every type of cellular component of SS regardless of the tumoral pattern (biphasic or not). No major differences were found between MSS and the nonglandular areas of BSS (not even regarding the presence of abortive glandular lumina). Cytoarchitectural transitions were frequently observed; these included spindle to epithelioid cell types and fascicular to solid (MSS and BSS) or fascicular to glandular (BSS) patterns. These findings support the assumption that spindle cells of SS are neoplastic and may evolve to glandular cells in SS. Based on the cytogenetic data pointing to a common pathogenesis of both phenotypes (BSS and MSS), SS may represent true carcinomas of soft tissues with a biphasic and/or monophasic pattern depending on the degree of differentiation.
Department of Pathology, Medical School of Porto, Hospital S João, Portugal.
J M
JM
Lopes
B
B
Bjerkehagen
M
M
Sobrinho-Simoes
J M
JM
Nesland
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002296:Carcinosarcoma / Q000145:classification* / Q000556:secondary / Q000648:ultrastructure*; D005260:Female; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000648:ultrastructure; D013584:Sarcoma, Synovial / Q000145:classification / Q000556:secondary / Q000648:ultrastructure*; D012983:Soft Tissue Neoplasms / Q000145:classification / Q000556:secondary / Q000648:ultrastructure*