Last major update: November 2008 - next update November 2009
Revised: 28 June 2009
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Copyright: (c) 2002-2009, PathologyOutlines.com, Inc.
● All melanocytes are within the dermis
● Also called intradermal nevus
● Most common adult type of nevus; represents the final stage in progression from junctional to compound to dermal nevus
● Seen mainly after adolescence
● Flat, pedunculated or papillary, often hairy
● Flesh colored or lightly pigmented (usually become lighter over time)
● Pigmentation may be in flecks up to 1 cm
● Melanomas only rarely arise from intradermal nevi (Dermatology 1998;196:425)
● Rarely has cerebriform appearance (Cutis 2004;73:254), and these nevi may be congenital
● Prominent schwannian differentiation (Am J Dermatopathol 2002;24:39)
● Osseous metaplasia/Osteo-nevus of Nanta (Dermatol Online J 2007;13(4):16)
Mole with osseous metaplasia
● Brown pigment (78%) white areas (53%), comma shaped vessels (50%), hair (47%), hairpin vessels (22%), comedolike openings (22%), dotted vessels (19%) (Dermatol Surg 2007;33:1120)
● Small nests of melanocytes in upper dermis, often around pilosebaceous units, with variable pigmentation and cellularity
● May have multinucleated melanocytes; deeper portion is usually less pigmented and less cellular and may have Wagner-Meissner corpuscles (representing neural portion of nevus)
● Mucin in 3% in stroma and within nests of nevus cells (Am J Dermatopathol 2008;30:236)
● Rarely nevus giant cells, balloon cells, infiltration by fat cells or osseous metaplasia
● No junctional component
● Can also be classified as Unna’s pattern (purely adventitial lesion confined to expanded papillary dermis and often to perifollicular dermis, usually neck, trunk or limbs) or Miescher’s pattern (melanocytes diffusely infiltrate adventitial and reticular dermis in wedge shaped pattern, usually on face) (Am J Dermatopathol 2007;29:141)
Low power Medium power
With adjacent fibrohistiocytic proliferation
Intradermal nevus with osseous metaplasia
Unna’s pattern - Contributed by Angel Fernandez-Flores, MD, PhD, Hospital El Bierzo and Clinica Ponferrada, Spain
End of Skin-Melanocytic Tumors > Dermal nevus
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