Skin melanocytic tumor
Spitzoid neoplasms, BAP1 inactivated neoplasms, and deep penetrating nevi
Atypical Spitz tumor
Author: Christopher S. Hale, M.D.
Topic Completed: 1 March 2013
Minor changes: 15 May 2019
Copyright: 2002-2019, PathologyOutlines.com, Inc.
PubMed Search: Atypical Spitz nevus
See also: Spitz nevus
Table of Contents
Definition / general | Terminology | Epidemiology | Clinical features | Case reports | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Molecular / cytogenetics description | Differential diagnosisCite this page: Hale C. Atypical Spitz tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumormelanocyticatypicalspitz.html. Accessed August 3rd, 2020.
Definition / general
- Junctional or compound lesion not fulfilling the histopathologic criteria of melanoma but with one of the following features:
- Asymmetry
- Predominance of single melanocytes over nests in lesions 4 mm or larger
- Ulceration
- Large dermal sheets of melanocytes
- Lack of maturation in dermis
- Deep dermal mitotic figures
- Extensive involvement of subcutis
- Nuclear pleomorphism (Mod Pathol 2006;19:S21)
Terminology
- Also called Spitz tumor with one or more atypical features
Epidemiology
- Mostly young patients
Clinical features
- Regional lymph node involvement in up to 1/3 (Hum Pathol 2006;37:816)
- Usually large and deep with pushing borders into dermis and subcutis
Case reports
- Resembling dermatofibroma clinically (Clin Exp Dermatol 2008;33:309)
Treatment
- Poor prognostic factors include size > 1 cm, tumor extension into subcutis, ulceration, high mitotic index and older age (Arch Dermatol 1999;135:282, Hum Pathol 1998;29:1105)
- Borderline biologic behavior between Spitz nevus and malignant melanoma (Mod Pathol 2005;18:197)
- Complete excision recommended to determine depth and extension; some recommend sentinel node biopsy, particularly if melanoma is suspected (Ann Surg Oncol 2008;15:302, Semin Diagn Pathol 2008;25:95 but see Adv Anat Pathol 2008;15:253)
Microscopic (histologic) description
- Junctional or compound lesion not fulfilling the histopathologic criteria of melanoma but with one of the following features:
- Asymmetry
- Predominance of single melanocytes over nests in lesions 4 mm or larger
- Ulceration
- Large dermal sheets of melanocytes
- Lack of maturation in dermis
- Deep dermal mitotic figures
- Extensive involvement of subcutis
- Nuclear pleomorphism (Arch Dermatol 2005;141:1381, Cancer 2003;97:499)
Microscopic (histologic) images
AFIP images
Images hosted on other servers:
Buttock tumor:
Large epithelioid cells with amphophilic cytoplasm
are characteristic of Spitz nevi and the nuclear atypia
observed here should not suggest melanoma in the
absence of other features
Images hosted on other servers:
Various images
Various images
Asymmetry but highly cohesive nests
Buttock tumor:
Multinucleated tumor cells
Sheets of atypical tumor cells with frequent mitotic figures
Somewhat symmetric
Large nests of atypical tumor cells
Positive stains
- S100, HMB45 only at dermoepidermal junction or superficially
- MelanA / MART1
Molecular / cytogenetics description
- HRAS occasionally but usually not NRAS or BRAF mutations, unlike melanoma (Am J Surg Pathol 2005;29:1145)
- Some cases may have copy number loss of the CDKN2A gene, also seen in melanoma (Br J Dermatol 2007;156:1287)
- Subset have BRAF mutation / loss of BAP1 (Am J Surg Pathol 2012;36:818)
- Proteomic differences may distinguish atypical Spitz from spitzoid melanoma (Am J Dermatopathol 2012;34:82)
Differential diagnosis
- Melanoma evolving in a Spitz nevus
- Spitzoid melanoma
