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Bladder

Other tumors

Melanoma of bladder


Reviewers: Gillian Levy, M.D., Yale Medical Center (see Reviewers page)
Revised: 21 April 2011, last major update April 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.

Definition
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● Primary tumors are rare (<50 cases reported) and are associated with melanosis; metastases are much more common

Epidemiology
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● Ages 44-81 years
● No gender preference

Sites
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● Bladder and urethra

Etiology
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● Metastatic lesion or primary lesion

Clinical features
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● Almost all reported cases are fatal
● Gross hematuria is the most frequent presenting symptom

Prognostic factors
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● Metastatic lesions, size and depth of invasion

Case reports
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● 80 year old woman with widespread melanosis in vagina and bladder developing into multifocal melanoma (Arch Pathol Lab Med 1991;115:950)
● 82 year old man with no known non-bladder tumor (Int J Urol 2006;13:635)
● Melanoma with melanosis exhibiting atypia (Arch Pathol Lab Med 1992;116:1213)

Treatment
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● Excision, possibly IL-2 (Urology 2003;62:351)

Clinical features
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● Cystoscopy: pigmented raised lesions; the clinical differential diagnosis includes endometriosis, melanoma and sarcoma

Gross description (Macroscopy)
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● Occurs throughout bladder, variable pigmentation

Gross images
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Metastatic melanoma with numerous black focal metastases seen in bladder mucosa


Metastatic melanoma with diffuse discoloration of the mucosa in 31 year old woman with melanoma removed from skin one year before her death from widespread metastases

Micro description (Histopathology)
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● Spindled or epithelioid; epithelioid cells often have marked pleomorphism, abundant cytoplasm, prominent eosinophilic nucleoli
● Necrosis and mitotic figures common
● Often atypical melanocytes

Micro images
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Left: melanosis (not melanoma); Right: Fontana Masson stain for melanin

   
Metastatic tumor (left: H&E, right: HMB45+)

Cytology description
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● Cells with pleomorphic nuclei singly or in clusters
● Spindle cells can be seen
● Often cytoplasmic melanin pigment and prominent eosinophilic nucleoli
● Malignant cells, some with cytoplasmic melanin; also macrophages containing melanin (Acta Cytol 2001;45:631)

Positive stains
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● S100, HMB45, other melanocytic markers

Negative stains
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● Keratin, vimentin

Differential diagnosis
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● Sarcoma, poorly differentiated carcinoma
Metastatic melanoma: clinical history of primary, although some primaries spontaneously regress so this may be difficult to conclusively establish; no bladder melanosis

End of Bladder > Other tumors > Melanoma of bladder


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