Case report: Bladder carcinoma with shadow cell differentiation: a case report with immunohistochemical analyses

Area of Science:

• Oncology
• Pathology
• Urology

Background:

• Bladder carcinoma presents diverse histological subtypes.
• Shadow cell differentiation (SCD) is an exceptionally rare feature in bladder cancer, mimicking cutaneous pilomatricoma.
• Understanding rare histological variants is vital for accurate cancer diagnosis.

Observation:

• A 67-year-old male smoker presented with lumbar pain, hematuria, and dysuria.
• Imaging revealed a 3 cm bladder tumor with suspicious lung and mediastinal masses.
• Transurethral resection showed high-grade urothelial carcinoma with squamous differentiation and SCD.

Findings:

• The bladder tumor exhibited high-grade urothelial carcinoma with partial squamous differentiation and shadow cell differentiation (SCD).
• Immunohistochemistry confirmed positive β-catenin in the peripheral squamous component.
• SCD, typically seen in hair matrix, was observed as a keratinization variant in this bladder carcinoma.

Implications:

• This case highlights the occurrence of SCD in bladder carcinoma, a rare phenomenon.
• Recognizing SCD in urothelial neoplasms is important for precise histopathological diagnosis.
• Further research into SCD in carcinomas may elucidate novel keratinization pathways and therapeutic targets.