Difficult differential diagnoses in testicular pathology.

CONTEXT: Although relatively rare, testicular cancer is the most common solid organ malignancy in young men and remains a leading cause of cancer death in this population. Different types of testicular tumors are treated differently, with an overall very high cure rate with proper management. Pathologists must, therefore, be familiar with important diagnostic pitfalls in testicular pathology, particularly those that result in different treatments or prognoses.
OBJECTIVE: To summarize key diagnostic features and useful ancillary tools for the most frequently encountered problems in testicular tumor pathology. DATA SOURCES: Current texts, PubMed (National Library of Medicine) articles, and archives at Indiana University School of Medicine and Beth Israel Deaconess Medical Center were all reviewed.
CONCLUSIONS: Problematic differential diagnoses include seminoma versus nonseminomatous germ cell tumors, germ cell tumors versus non-germ cell tumors, intratubular germ cell neoplasia versus atypical germ cells with maturation arrest, pseudolymphovascular invasion versus real lymphovascular invasion in germ cell tumors, and macroscopic Sertoli cell nodules versus Sertoli cell tumors. In almost all cases, awareness of the differential diagnostic possibilities based on routine light microscopic features permits application of either additional, directed observations or immunohistochemical studies that lead to an accurate diagnosis.