Selected common diagnostic problems in urologic pathology: Perspectives from a large consult service in genitourinary pathology

Context.-Several common differential diagnoses are encountered in urologic pathology, frequently causing patient referrals for a second opinion. Objectives.-To review 3 common differential diagnoses encountered in a large consultation service in genitourinary pathology, including partial atrophy versus prostatic acinar adenocarcinoma, oncocytoma versus chromophobe renal cell carcinoma, and urothelial carcinoma in situ versus normal urothelium and reactive atypia. We will discuss the detailed, morphologically distinctive features and the usefulness of immunohistochemistry. Data Sources.-Personal experience and review of the current literature. Conclusions.-Careful morphologic assessment and awareness of diagnostic pitfalls are fundamental in reaching a definitive diagnosis in most cases. Immunohistochemistry is useful but should be used only in conjunction with the morphologic impression.