Sertoli--Leydig cell tumor with endometroid differentiation. Case report and discussion of histogenesis.

A case of Sertoli-Leydig cell tumor with endometrioid differentiations is reported. The tumor was associated with hirsutism and androgenic excess which normalized following surgical removal. On light-microscopic study, the tumor resembled a well-differentiated endometrioid tumor with luteinized stroma. With further study, the interstitial stromal cell were recognized as Leydig cells, containing scattered Reinke crystals. Tubules and solid cords reminiscent of sex cord elements were also recognized. The dilated glandular elements showed scant apical and luminal positivity with the PAS stain following diastase digestion. Electron-microscopic examination confirmed a dual population of cells, featuring Sertoli-Leydig cell tumor and endometrioid cells. We postulate that this tumor may represent yet another example of multidirectional differentiation.