Microscopic Description:

Spindle or epitheliod cells. The epitheliod cells often have marked pleomorphism, abundant cytoplasm, and “prominent,” eosinophilic nucleoli , Necrosis and mitotic figures, atypical melanocytes.

Immunohistochemical Stains: Positive for S100, HMB45 & other melanocyte markers.

Negative for keratin, vimentin.

Discussion:

Melanomas affecting the urinary bladder and urethra are uncommon.

The lesions can occur as primary tumors or metastases.

Bladder metastases typically arise from primary tumors in the genitourinary tract (prostate, cervix) and adrenal gland.

Though comparatively rare, melanoma is the leading cause of bladder metastases among cancers originating from distant sites, followed by breast, lung, and gastric carcinomas.

Epidemeology- 44 years and 81 years of age, no gender preference.

Asymptomatic, if symptomatic- Hematuria is the most common presentation.

Frequently undiagnosed, which contributes to their discovery primarily during autopsy examinations.

Cystoscopy: a definitive diagnostic modality, reveal pigmented, nodular, or vegetating lesions on the bladder wall. Confirmed through biopsy and histopathology.

Cytology Features. Cells with pleomorphic nuclei singly or in clusters may be seen, Spindle cells, cytoplasmic melanin pigment and prominent eosinophilic nucleoli with cytoplasmic melanin and/or melanin laden macrophages.

References:

Faria, Silvana & Hwu, Wen-Jen & Curley, Steven. (2023). Metastases to Abdominal-Pelvic Organs. 10.1016/B978-0-323-69538-1.00032-X.

Kumar RA, Batra N, Frankel J, Kumar U. Melanoma metastasis to the bladder: a case report. Urology Case Reports. 2022 Jan 1;40:101941. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8601986/

Rahoui Moez, Mrad Daly Khaireddine, Wajih Sahnoun, Alia Zehani, Mokhtar Bibi, Yassine Ouannes, Ahmed Sellami, Sami Ben Rhouma, Yassine Nouira, Symptomatic bladder metastasis of malignant melanoma: a case report, Journal of Surgical Case Reports, Volume 2020, Issue 12, December 2020, rjaa509, https://doi.org/10.1093/jscr/rjaa509

Reyes RM, Zhang C, Deng Y, Ji N, Mukherjee N, Padron AS, Clark CA, Svatek RS, Curiel TJ. CD122-targeted interleukin-2 and αPD-L1 treat bladder cancer and melanoma via distinct mechanisms, including CD122-driven natural killer cell maturation. Oncoimmunology. 2021 Nov 22;10(1):2006529. doi: 10.1080/2162402X.2021.2006529. PMID: 34858732; PMCID: PMC8632314. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8632314/

CASE IMAGES