Penis and scrotum
Other malignancies
Melanoma

Authors: Antonio Cubilla, M.D., Alcides Chaux, M.D. (see Authors page)

Revised: 6 April 2018, last major update May 2010

Copyright: (c) 2002-2018, PathologyOutlines.com, Inc.

PubMed Search: Melanoma[TI] penis[TIAB]

Cite this page: Cubilla, A., Chaux, A. Melanoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/penscrotummelanoma.html. Accessed July 17th, 2018.
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
Treatment
Clinical images

Images hosted on PathOut server:

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

Images hosted on PathOut server:

Deeply invasive nodular tumor of glans



Images hosted on other servers:

Melanoma in situ

Glans

Glans with urethral involvement

Positive stains
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