The Morphologic Spectrum of Sertoliform Cystadenoma of the Rete Testis: A Series of 15 Cases.

Sertoliform cystadenoma of the rete testis (SCRT) is rare with only 9 cases reported to date in the literature, none with follow-up. Four large genitourinary pathology consult services were searched. We identified 15 cases of SCRT. Men were 21 to 84 years old (mean, 46 y) and had testicular discomfort or mass. Other findings were seminoma (n=1), spermatocele (n=2), hydrocele (n=1), varicocele (n=1), and scrotal hematoma (n=1). Eight had preoperative serum tumor markers, which were normal. Tumors ranged from 0.3 to 4 cm (mean, 1.5 cm). All of them were well circumscribed with solid and cystic features and occupied on average, 73% of the rete (20% to 100%). The tumors were mostly confined within dilated channels of the rete testis and showed classic features consisting of: (1) tubules with well-formed lumina in 87% of cases; (2) well-formed tubules with no lumina in 87% of cases; and (3) cords/nests in hyalinized or myxoid stroma in 73% of cases. Other patterns included: (1) solid/sheet growth in 26% of cases; (2) individual cells in 13% of cases; (3) festoons in 13% of cases; (4) branching tubules in 7% of cases; and (5) papillary in 7% of cases. Cells were cuboidal with round to oval nuclei with small nucleoli, except at the periphery where projections into rete tubules had a more columnar appearance. In the festooning pattern, nuclei were pseudostratified and columnar with prominent nucleoli and nuclear grooves. In 4 cases, tumor extended into adjacent seminiferous tubules surrounded by dense peritubular fibrosis, with in some cases small cysts lined by flattened epithelium containing pale lightly granular material. All cases lacked necrosis and significant atypia. Mitoses ranged from 0 to 2 per 10 high-power field. Follow-up ranged from 4 to 170 months with mean of 97 months. For the 13 cases with information, all patients were alive, except for 3 who died of either unrelated causes (9.2 and 10 y) or of unknown cause (4.8 y at age 89 y). We performed immunohistochemistry for steroidogenic factor 1 and inhibin in 4 of our cases, where 3 (75%) were positive for both markers. We also describe 2 additional cases which morphologically resembled SCRT but had more atypical features. This study highlights that SCRT has variable morphology. We also verify the benign nature of the lesion and its lack of association with any syndromes.