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: 3 November 2020
Copyright: 2002-2021, 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 CS. Atypical Spitz tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumormelanocyticatypicalspitz.html. Accessed March 3rd, 2021.
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
Large epithelioid
cells with
amphophilic
cytoplasm
Images hosted on other servers:
Various images
Atypical Spitz tumor
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
