Nested melanoma

•A variant of nevoid melanoma

•Predominately in the middle-aged & elderly (mostly 60 years or more)

•Predisposition for the trunk & limbs

•>6.0 mm diameter

•Globular pattern on dermoscopy

•Asymmetry & poor circumscription

•Variably sized, variably located, expansile, cannon ball-like intra-epidermal nests with thinned surrounding epidermis

•Finely granular pigment often evident

•Nests lack rete ridge tip preferential location

•Bridging sometimes present & can be marked

•Occasional dendritic cells

•Variable atypia & mitotic activity

•Variable Pagetoid spread

•Similar dermal component when present

•May express BRAF-V600E & PRAME, variable HMB45

•CGH shows multiple chromosomal aberrations

Differential diagnosis

Nested melanoma must be distinguished from a junctional nevus. The latter is characterized by smaller nests showing a predilection for the rate tips. A recurrent nevus may appear similar but the presence of dense scarring obviously favors the latter. Clinical information is necessary to avoid a misdiagnosis.

One response to “Nested melanoma”

  1. alicerobertsmd avatar
    alicerobertsmd

    These can be a challenge!

    Like

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