True Papillae and Squamous Features in Prostate Carcinoma Represent a Potential Diagnostic Pitfall: Report of 3 Patients.
Ioanna-Maria Grypari, Angeliki Pomoni, Dimitra Ganetsou et al.
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Case in brief
Three patients presented with hematuria and bladder lesions that resembled invasive high-grade urothelial carcinoma in limited transurethral resection specimens. The tumors showed papillae lined by markedly atypical, multilayered epithelium, brisk mitoses, and muscularis propria invasion; one also had squamoid differentiation. Immunohistochemistry supported prostatic origin, with androgen receptor and NKX3.1 expression and negative urothelial markers. The diagnosis was high-grade prostate adenocarcinoma involving the bladder. Additional clinical information included prior prostate cancer in two patients, androgen ablation in one, and a PSA level of 70 ng/ml in another.
What made this case unusual
The tumors displayed true papillae lined by high-grade multilayered epithelium, with marked pleomorphism and brisk mitotic activity—morphology that strongly mimicked urothelial carcinoma; one case also showed squamoid differentiation.
Diagnostic / clinical pearl
When a bladder lesion resembles high-grade urothelial carcinoma, correlate with prior diagnoses and clinical history, and use a focused immunohistochemical panel to assess prostatic versus urothelial origin.
Why it matters
Misclassification can have significant therapeutic implications, particularly when PSA data or a complete clinical history is unavailable.