Skin-Melanocytic Tumors - Nodular melanoma

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Skin-Melanocytic Tumors

Nodular melanoma

Last major update: November 2008 - next update November 2009

Revised: 22 September 2009

Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.

Clinical

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● 15-30% of melanoma patients

● Affects all body surfaces, but usually legs and trunk

● Rapid growth; comprises 34% of thick (2 mm+) melanomas (Arch Dermatol 2005;141:745)

● Higher risk for metastases due to vertical growth phase, but differs from “vertical growth melanoma” (J Dermatol 2008;35:643)

● May recur even in sentinel lymph node negative patients (Surgeon 2006;4:153)

● Median age 63 years; screening methods have had little impact on this subtype (Cancer 2008 Nov 5 [Epub ahead of print] )

Case reports

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● 25 cm tumor (Dermatol Online J 2007;13(2):7)

● Metastatic amelanotic tumor during pregnancy (Medicina (Kaunas) 2008;44:467)

● With Spitz nevus like features (J Dermatol 2007;34:821)

Clinical description

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● Smooth nodule covered by normal epidermis, elevated blue-black plaque or ulcerated polypoid mass

● Usually no lateral flat component

Clinical images

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25 cm tumor Various images

Dermoscopy

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● Nonspecific global dermoscopic patterns of globules, blue-white veil, atypical vessels and structureless areas (Arch Dermatol 2008;144:1311)

Micro description

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● No radial growth phase

● Epidermis is thin and may be ulcerated

● No in situ melanoma

● Dermal component consists of a cohesive nodule of tumor cells with pushing border

● Cells are most commonly epithelioid, may be spindled or small with occasional monster cells (Am J Dermatopathol 2005;27:208)

Micro images

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Contributed by John Irlam, D.O., Department of Pathology, University of Toledo Medical Center:

Low power (4x)

Medium power (10x)

Medium power (20x)

High power (40x)

Ki-67 staining

Molecular / cytogenetics

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● B-RAF and N-RAS mutations in 25-30% (J Invest Dermatol 2005;125:312)

Differential diagnosis

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● Primary dermal melanoma - no in situ component, ulceration, regression, associated nevus (Arch Dermatol 2008;144:49)

End of Skin-Melanocytic Tumors > Nodular melanoma

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