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Skin-Melanocytic Tumors
Last major update: November 2008 - next update November 2009
Revised: 22 September 2009
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Copyright: (c) 2002-2009, PathologyOutlines.com, Inc.
Clinical
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● 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 or nodule or verrucous lesion
Case reports
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● Metastatic tumor to sentinel lymph node in 4 year old child (J Cutan Pathol 2003;30:647)
● Multiple primary nevoid melanomas in HIV/AIDS patient (J Am Acad Dermatol 2002;47:S172)
Clinical description
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● Tan nodule 1 cm or larger on trunk or proximal limbs of young adult
Micro description
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● Resembles ordinary compound or dermal nevus at low power, with symmetrical dome shaped or verrucous and papillomatous features, sharp lateral demarcation, inconspicuous junctional component, no pagetoid growth
● High power shows relatively bland and monomorphic cells resembling classic nevus or epithelioid cells in Spitz nevus
● However, there is subtle pleomorphism and impaired maturation with depth
● Focal sheetlike growth pattern, nucleoli in tumor cells at base of lesion
● Multiple dermal mitoses with atypical mitoses
Micro images
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Various images Fig 3-6
Other images: lesion #1 - image #1; #2; #3; #4; lesion #2 - #1; #2; #3; #4; #5; lesion #3 - #1; #2; atypical single cells #1; #2; mitotic figures #1; #2
Virtual slides
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Positive stains
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● HMB45 (strong throughout, J Cutan Pathol 1995;22:502)
● Increased labeling indexwith Ki-67
● Diffuse staining with cyclin D1
Differential diagnosis
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● Minimal deviation melanoma - at most moderate atypia, at least Level III due to dermal invasion, remnants of existing nevi usually present, usually few mitotic figures
● Nodular melanoma - high grade atypia, intraepidermal atypia
● Melanoma arising in dermal nevus - residual nevus present, often tumor extension into deep reticular dermis and fat
Additional references
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● Hum Pathol 1995;26:171, Arch Dermatol Res 1985;277:362
End of Skin-Melanocytic Tumors > Nevoid melanoma
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