Penis & scrotum
Other malignancies
Melanoma
Authors: Alcides Chaux, M.D., Antonio L. Cubilla, M.D.
Topic Completed: 1 May 2010
Minor changes: 28 October 2020
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Melanoma[TI] penis[TIAB]
Table of Contents
Definition / general | Epidemiology | Sites | Etiology | Clinical features | Prognostic factors | Case reports | Treatment | Clinical images | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Differential diagnosisCite this page: Chaux A, Cubilla AL. Melanoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/penscrotummelanoma.html. Accessed January 22nd, 2021.
Definition / general
- Relatively rare tumor of penis, similar to counterparts elsewhere
- ICD-O: 8720 / 3
Epidemiology
- White men ages 50 - 70 years
Sites
- Preferential location is glans (60 - 80%) followed by shaft and foreskin
- Distal urethra location is exceedingly uncommon and tends to affect the fossa navicularis
Etiology
- Risk factors include preexisting nevi, ultraviolet radiation and history of melanomas elsewhere
Clinical features
- Most common tumor in penis after squamous cell carcinoma but accounts for < 1% of all penile malignant tumors
- Small, brown to black lesions similar to melanomas elsewhere
- Ulceration is common
- Distal urethra melanomas are typically polypoid
- 50% have inguinal nodal metastases at diagnosis
Prognostic factors
- Poor prognostic factors: presence of ulceration, tumor depth > 3.5 mm, tumor size (diameter) > 15 mm, nodal or distant metastases (Urology 2007;70:143)
Case reports
- 64 year old with melanoma in situ of glans (Eur J Dermatol 2005;15:113)
Treatment
- Partial penectomy or wide local excision (J Urol 2005;173:1958)
- Close followup for recurrence (Urology 2008;72:1185.e15)
Clinical images
AFIP images
Ulcerated dark
mass involves
the prepuce and
coronal sulcus
Images hosted on other servers:
Melanoma in situ
Gross description
- Flat dark macula, ulcer or black-blue-red nodule with irregular edges
Microscopic (histologic) description
- Radial and vertical growth phases similar to melanoma elsewhere
- Variegated growth patterns are solid, nested, fusiform or mixed
- Polygonal neoplastic cells with abundant eosinophilic cytoplasm and marked nuclear atypia
- Coarse brown intracytoplasmic pigment in most cases
- Abundant and atypical mitoses
- Clear, vacuolated, rhabdoid or pleomorphic cells in some cases
- Preexisting or coexisting melanosis, melanotic nevi (J Cutan Pathol 2009;36:444) or lentiginous melanosis is occasionally found
Microscopic (histologic) images
AFIP images
Deeply invasive nodular tumor of glans
Images hosted on other servers:
Melanoma in situ
Glans
Glans with urethral involvement
Differential diagnosis
- Benign melanocytic neoplasia: maturation present; no nuclear pleomorphism, no pagetoid spread
- Paget disease: very difficult to distinguish from melanoma morphologically in radial growth phase; positive for MUC1, MUC5AC, CAM 5.2, EMA, CEA and GCDFP-15; negative for melanocytic markers
- Penile primary sarcoma: no intraepithelial component, no melanin in tumor cells; negative for melanocytic markers
- Sarcomatoid carcinoma: nests of squamous cells within the tumor, PeIN present, no melanin in tumor cells, positive for pancytokeratin, CK 34 beta E12 and p63; negative for melanocytic markers
