Endometrial stromal nodule

Several endometrial stromal tumor variants have been described (Fig. 18.18). These include the smooth muscle variant (also referred to as mixed endometrial stromal and smooth muscle tumor or stromo-myoma), fibromyxoid variant,sex cord variant, and variants including endometrioid glands or epithelioid cells. The key to understanding the immunophenotype of these tumors is that variant or metaplastic elements often lose the phenotype of endometrial stroma and acquire the phenotype of the corresponding metaplastic element. Therefore, the smooth muscle in a smooth muscle variant of endometrial stromal nodule expresses muscle markers (Fig. 18.18B) and is frequently CD10-negative. T20 endometrioid... 

ENDOMETRIAL STROMAL NODULE AND LOW-GRADE ENDOMETRIAL STROMAL SARCOMA... 

Oliva E, Young RH, Clement PB, et al. Cellular benign mesenchymal tumors of the uterus A comparative morphologic and immunohistochemical analysis of 33 highly cellular leiomyomas and six endometrial stromal nodules, two frequently confused tumors. Am J Surg Pathol. 1995 19 757-768. 

Endometrial stromal neoplasms, both nodules and sarcomas, almost always express CDIO, ER, PR, and WTl (Fig. 18.17).138>141-143,213,214 Many also express P-catenin.2i 2i They frequently express smooth muscle actin,i°°40i,i38,2i4 cytokeratin, 4i4 qj- androgen receptors patchily. They only unusually express des-j inioo,i35,2i9,220 CD34 (unpublished observation) in varieties where the constituent cells resemble non-neoplastic proliferative endometrial stroma. Diffuse desmin and h-caldesmon expression supports smooth muscle differentiation and disqualifies categorization as an endometrial stromal tumor except in rare cases. 

---