Amelanotic Malignant Melanoma of the Male Urethra: A Potential Diagnostic Pitfall

Abstract

A rare disease in an unusual site can closely mimic a typical presentation of a common disease, sometimes with devastating consequences. We present a case of primary amelanotic malignant melanoma of the urethra in a male, with clinical and histological characteristics that could have led to a mistaken diagnosis of high-grade urothelial carcinoma. Amelanotic mucosal melanoma should be suspected in all cases of high-grade mucosal tumors with practically any appearance (epithelioid, sarcomatoid, anaplastic, mixed). Morphological hints pointing toward melanoma—such as the presence of sparse melanin pigment or melanoma in situ—should be sought, and if absent, an immunohistochemical panel comprising S100 and HMB45 should be performed.

Prostatic stromal sarcoma: Report of a rare case in a young male and review of the literature

“…Malignant melanoma can involve the whole genitourinary tract including the prostate, both as a primary neoplasm and by metastasizing from other sites [12] , [13] . Due to its protean morphology, including possible sarcomatoid aspects, it should be ruled out too [14] , [15] . Neoplasms of the specialized stroma of the prostate are graded from STUMP to high-grade PSS using four characteristics: necrosis, cellularity, mitoses and stromal overgrowth.…”

Hematuria in breast cancer: don’t forget bladder metastases!

“…Metastases to the urinary bladder are rare and can sometimes mimic other more common entities, which makes them exquisitely tricky to diagnose 12 , 13 . Even worse, invasive lobular carcinoma of the breast can metastasize to the bladder without forming a discrete mass, requiring a high degree of suspicion and skill to diagnose 14 .…”

The best prostate biopsy sampling system—fusion and systematic biopsy: A single center experience

“…For each case, the 15 biopsy cores were placed each in its own cassette and processed by the pathology department according to standard procedures. 15,16 Where present, PCa was graded separately for each core using ISUP grade groups (GG). 17 Two pathologists (ADA, AC) evaluated each case separately and disagreements were resolved by discussion.…”