Table of ContentsDefinition / general | Terminology | Epidemiology | Clinical features | Case reports | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Differential diagnosis
Cite this page: Hale CS. Nevoid melanoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skintumormelanocyticnevoidmelanoma.html. Accessed May 30th, 2020.
Definition / general
- Synonym: "verrucous pseudonevoid melanoma"
- Distinct from controversial term "minimal deviation melanoma"
- Rare variant characterized by morphologic features of nevus
- Behavior similar to other melanomas; may recur or metastasize causing death (Am J Dermatopathol 2001;23:167)
- Key to diagnosis is high index of suspicion
- Dome shaped papule, nodule or verrucous lesion
- Tan nodule 1 cm or larger on trunk or proximal limbs of young adult
Microscopic (histologic) description
- Resembles ordinary compound or dermal nevus at low power, with symmetrical dome shaped or verrucous and papillomatous features, sharp lateral demarcation, inconspicuous junctional component and no pagetoid growth
- High power shows relatively bland and monomorphic cells resembling classic nevus or epithelioid cells in Spitz nevus
- Focal sheetlike growth pattern, nucleoli in tumor cells at base of lesion
- Multiple dermal mitoses with atypical mitoses
- Subtle pleomorphism and impaired maturation with depth
Microscopic (histologic) images
- Melanoma arising in dermal nevus: residual nevus present, often tumor extension into deep reticular dermis and fat
- Metastatic melanoma
- Minimal deviation melanoma: at most moderate atypia, at least level III due to dermal invasion, remnants of existing nevi usually present and usually few mitotic figures
- Nodular melanoma: high grade atypia, intraepidermal atypia