An Unusual Benign Uterine Stromal Spindle Cell Tumor Harboring JAZF1::BCORL1 : International Journal of Gynecological Pathology

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Pathology of the Corpus: Case Reports

An Unusual Benign Uterine Stromal Spindle Cell Tumor Harboring JAZF1::BCORL1

Rodriguez Pena, Maria D.C. M.D.; Mubeen, Aysha M.D.; Harada, Shuko M.D.; Prieto Granada, Carlos N. M.D.

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International Journal of Gynecological Pathology 42(3):p 319-324, May 2023. | DOI: 10.1097/PGP.0000000000000894


Uterine mesenchymal lesions demonstrate various underlying genomic alterations involving MED12, JAZF1, YWHAE, BCOR, and ALK genes, among others. Recent publications describe a subset of high-grade endometrial stromal sarcoma lesions harboring BCORL1 gene aberrations including JAZF1::BCORL1. Herein, we present an unusual benign endomyometrial spindle cell lesion that defies classificatory efforts by demonstrating mixed histomorphologic and immunohistochemical features of endometrial stromal nodule, leiomyoma, and uterine inflammatory myofibroblastic tumor while harboring a JAZF1::BCORL1. The lesion was found in a 43-yr-old woman with pelvic pain and heavy menses as a 5.5 cm well-circumscribed ulcerated mass fungating from the cervical os. Microscopic examination revealed a polypoid, well-circumscribed, moderately cellular endomyometrial tumor composed by bland spindle cells haphazardly disposed within a slightly edematous stroma enriched by a delicate network of thin-walled vessels that were occasionally encircled by the tumor cells. Unequivocal evidence of tongue-like growth pattern into the myometrium, tumor-type necrosis or increased mitotic activity was not identified after sampling the entire lesion. The lesion showed patchy immunoreactivity for both smooth muscle actin-alpha and desmin while negative for CD10, HMB45, ALK (D5F3), and BCOR. An Archer FusionPlex panel assay demonstrated a fusion involving both exons 4 from the JAZF1 and BCORL1 genes. The JAZF1::BCORL1 has not, to the best of our knowledge, been previously reported in a benign/low-grade mesenchymal uterine lesion.

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