Spindle Cell Sarcoma of the Uterus Harboring MEIS1:NCOA1 Fusion Gene and Mimicking Endometrial Stromal Sarcoma. (April 2023)

• Record Type: Journal Article
• Authors: Mejbel, Haider A.; Harada, Shuko; Stevens, Todd M.; Huang, Xiao; Netto, George J.; Mackinnon, Alexander C.; Al Diffalha, Sameer
• Is Part Of: International journal of surgical pathology. Volume 31:Number 2(2023)
• Page Start: 227
• Page End: 232
• Publication Date: 2023-04
• Subjects: MEIS1 -- NCOA1 -- fusion gene -- spindle cell sarcoma -- endometrial stromal sarcoma; Pathology, Surgical -- Periodicals; 617.07
• DOI: 10.1177/10668969221098081
• Languages: English
• ISSNs: 1066-8969

Abstract

MEIS1::NCOA1/2 sarcomas are a newly recognized group of exceedingly rare low-grade spindle cell sarcomas that often involve the genitourinary and gynecologic tracts. Due to its deceptively low-grade morphology and the non-specific immunoprofile, these neoplasms may pose a diagnostic challenge by histologically mimicking other entities such as endometrial stromal sarcoma, smooth muscle tumor, or uterine perivascular epithelioid cell tumor (PEComa). Histologically, MEIS1::NCOA1/2 sarcomas typically show spindle cell proliferation with hyperchromatic nuclei and a generalized cytologic uniformity, arranged in short fascicles and exhibiting alternating zones of hypo- and hypercellularity. Among the previously reported cases, molecular analysis revealed the MEIS1::NCOA2 fusion as the most commonly detected fusion gene, whereas the MEIS1::NCOA1 fusion gene has been reported in only a single case that involved kidney. Herein we report the first case of uterine sarcoma harboring the MEIS1::NCOA1 fusion gene that was initially misclassified as low-grade endometrial stromal sarcoma, demonstrating its clinicopathologic features, and highlighting the essential role of molecular pathology to arrive at the accurate diagnosis that may alter disease classification and inform therapy.