Comparative immunomorphology of testicular Sertoli and sertoliform tumors

Sertoli 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.