Original contributionComparative immunomorphology of testicular Sertoli and sertoliform tumors

•Sertoli cell and sertoliform tumors of the testis are very uncommon•Some Sertoli cell tumors resemble atrophic tubules by morphology and phenotype•Sclerosing Sertoli cell tumor variant shows a markedly different phenotype•Sertoliform rete testis adenoma mimics Sertoli tumors but stains like rete testis•Immunohistochemistry is useful in the subclassification of Sertoli tumors

SummarySertoli cell (SC) and sertoliform tumors of the testis are very uncommon; for this reason their differential diagnosis and classification can be challenging. We applied an extensive immunophenotypic panel that included androgenic hormones, enzymes and receptors, neuroendocrine, lineage and genitourinary markers to a series of these lesions to determine if and which immunostains can aid in their diagnostic workup. Study cases included: 2 androgen insensitivity syndrome-associated SC adenomas, 3 SC tumors (SCT) not otherwise specified (SCT-NOS), 3 sclerosing SCT, 2 large cell calcifying SCT, 1 SCT with heterologous sarcomatous elements, 1 malignant SCT, and 1 sertoliform rete testis adenoma (sertoliform RTA). We found that SCT-NOS and variants with sclerosis showed a phenotype akin to atrophic seminiferous tubules characterized by gain of expression of pankeratin, calretinin, CD56, which are negative in normal SC. Distinctive phenotypes were identified in: sclerosing SCT: androgen receptors (AR) + (strong)/PAX2/PAX8+ (subset)/S100+/inhibin−; large cell calcifying SCT: calretinin+ (strong)/S100+/AR−; sertoliform RTA: PAX2/PAX8+/pankeratin+/inhibin−. Androgenic hormones and enzymes did not show diagnostic utility. A panel of calretinin, inhibin, pankeratin, S100, PAX2/PAX8, and AR consistently allowed distinction between variants of Sertoli and sertoliform tumors.