Microcystic urothelial carcinoma: a case report

Area of Science:

• Uro-oncology
• Pathology
• Oncologic Imaging

Background:

• Microcystic urothelial carcinoma (MUC) is a rare, aggressive variant of urothelial carcinoma with unclear histologic and immunohistochemical features.
• Limited case data hinders a comprehensive understanding of MUC's behavior and diagnostic criteria.

Observation:

• A 71-year-old female presented with hematuria and abdominal pain, exhibiting bladder wall thickening and a soft tissue mass involving the bladder, left lower ureter, and unclear pelvic organ boundaries.
• Imaging revealed enlarged lymph nodes, while cystoscopy showed diffuse bladder wall thickening, edema, and bleeding. Histopathology confirmed high-grade invasive urothelial carcinoma.

Findings:

• Microscopic examination revealed infiltrative growth with cystic structures, frequent mitoses, and stromal mucus. The left ovary showed metastasis of the same cancer type.
• Immunohistochemistry results included CK5/6+, p63+, Pax-8, MUC5AC, CK7, and Ki67 at 50%. Postoperative pathology confirmed MUC involvement of the left ureter with ovarian metastasis.
• The patient died two months post-surgery due to vascular invasion, underscoring the aggressive nature of MUC.

Implications:

• The bland morphology and lack of specific markers in MUC can lead to missed diagnoses and misdiagnosis by pathologists.
• This case report and literature analysis aim to enhance the understanding of MUC's characteristics, diagnosis, and aggressive behavior.
• Early and accurate diagnosis is crucial for appropriate management and potentially improving outcomes for patients with this rare urothelial carcinoma variant.