Abstract

Most neoplastic scrotal masses ultimately prove to be germ cell tumors and are recognizable with routine hematoxylin and eosin stained sections. The differential diagnosis may be focused, even before reviewing histologic sections, by knowledge of patient age, medical history, tumor site (testicular vs. paratesticular), and gross findings. Some cases may prove to be diagnostically challenging, including: rare tumors, a common tumor with an unusual pattern, a metastatic tumor, or a neoplasm having features that mimic another tumor. Several morphologic patterns are seen with some frequency and these generate recurring sets of differential diagnostic considerations. These common patterns include testicular tumors with a predominant diffuse arrangement of cells with pale to clear cytoplasm, tumors with a glandular/tubular pattern, tumors with a microcystic pattern, and tumors composed of oxyphilic cells. Intratubular proliferations of atypical cells, paratesticular glandular and/or papillary tumors, or tumors with spindle cell morphology can also be challenging to diagnose correctly. In some problematic cases, immunohistochemical staining may be useful to resolve these differential diagnoses.