Skin - Melanocytic tumor
Nevi
Pigmented spindle cell nevus

Author: Christopher Hale, M.D. (see Authors page)

Revised: 27 February 2017, last major update February 2013

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Pigmented spindle cell nevus

Cite this page: Pigmented spindle cell nevus. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skintumormelanocyticpigmentedspindlecellnevus.html. Accessed March 25th, 2017.
Definition / General
  • First described by Reed in 1975
  • Heavily pigmented nevus, often recent onset, widely considered a Spitz nevus variant (J Am Acad Dermatol 1993;28:565)
  • Clinically and histologically simulates melanoma
Terminology
  • Also called Reed's nevus
Epidemiology
Sites
Clinical Features
  • < 1 cm, solitary, deeply pigmented and well circumscribed maculopapule
  • Clinically resembles melanoma
Case Reports
Treatment
  • Conservative but complete excision
  • Does not recur
Dermoscopy
  • Two patterns reported:
    1. Brown to blue pigmentation with peripheral rim of large brown globules (globular pattern)
    2. Dark diffused pigmentation and pseudopods regularly distributed at periphery in stellate or radiate pattern (starbust pattern, Dermatol Online J 2004;10:5)
Clinical Images

Images hosted on PathOut server:

Small and symmetrical lesion differs from Spitz
nevus in its uniform dark blue black pigmentation
that may suggest melanoma clinically (AFIP)



Images hosted on other servers:

Rim of brown globules around lesion

Pseudopods arranged regularly

Small multicolored lesion

Slightly raised dark lesion

Micro Description
  • Some similarity with Spitz nevi
  • Symmetric with cytologic maturation
  • Nests and fascicles of spindled melanocytes along dermoepidermal junction and within dermal papillae
  • May be junctional or compound
  • Expansive, not infiltrative growth pattern
  • Extends no deeper than reticular dermis
  • Nevus cells typically contain abundant melanin pigment, may be associated with melanophages
  • Nuclei are monotonous, resemble normal keratinocytes and may have small nucleoli
  • Often has architectural or cytologic atypia (Hum Pathol 1991;22:52)
  • Variable lymphocytic infiltrate at base of lesion
  • Variable transepidermal elimination of junctional nests
  • No / rare mitotic figures
  • Note: hypopigmented variant is similar but without abundant melanin (J Cutan Pathol 2008;35 Suppl 1:87)
Micro Images

Images hosted on PathOut server:

AFIP images:

Fig A: bilaterally symmetrical lesion has proliferation of nested melanocytes that "rain down" from epidermis and expand papillary dermis without involving reticular dermis
Fig B: lesional cells mature from superficial to deep
Fig C: the most lateral cells are in the form of a nest rather than single cells (well circumscribed)

Some intraepidermal nests show clefts similar to Spitz nevi, but they more often blend imperceptibly with keratinocytes in a pigmented spindle cell nevus (fig B);
Mitotic figures in the epidermis are common but they are not numerous in the dermis;
Maturation towards a small nevoid cell at the base in the papillary dermis, without involvement of the reticular dermis, is typical

Fig B: bilaterally symmetrical lesion whose cells mature from epidermis to base of papillary dermis, respecting the reticular dermis interface;
Fig C: nucleolated lesional cells with abundant, coarse and dusty pigment are characteristic



Images hosted on other servers:

Various images

Symmetric pigmented tumors


Symmetric pigmented tumor

Pigmented spindle cell tumor

Positive Stains
  • HMB45 highly expressed in intraepidermal component of pigmented spindle cell nevus (PSCN) and spindle cell melanoma but dermal component negative in PSCN, irregularly positive in spindle cell melanoma (Am J Surg Pathol 2011;35:1733)
  • Other melanocytic markers (S100, MelanA)
Molecular / Cytogenetics Description
Videos

Pigmented spindle cell nevus
Differential Diagnosis