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Spitz Nevus

last modified on: Sun, 06/25/2017 - 23:58

Spitz Nevus

 return to: Melanoma (Evaluation and Management)

 see also: Case Example Atypical Spitz Nevus

 Affirmed at Melanoma Tumor Board on 1-24-11 by Hoffman H, Swick B, Liu V, and Stone M

I. Definition of Spitz Nevus

A benign melanociytic proliferation that in some cases ("atypical" spitzoid lesions) can exhibit clinical and histologic features that resemble melanoma. As a result, melanocytic lesions that display spitzoid features can be challenging to precisely interpret and optimally manage.

Atypical spitz tumor may be difficult to distinguish from melanoma and are sometimes referred to as "STUMP" = 'Spitz tumor of undetermined malignant potential' to highlight the difficulty in assigning benign biological behavior to these lesions (Sade 2010)

Malignant spitzoid lesions are usually larger than 6mm, asymmetric, show numerous mitoses and other pathologic features.


The classic spitz lesion is defined by the presence of distinctive-appearing spindle or epithelioid cells on light microscopy in a recognizable nevus-like pattern. Spitz lesions share features with melanoma on light microscopic examination. When Spitz features are atypical or typical features are absent, distinction from melanoma can be difficult. (Clin Plast Surg, 2010 Jan; 37 (1): 21-33)

II. Management

SLN:

The role for sentinel lymph node biopsy in the management of atypical spitzoid lesions is controversial. Pathologic interpretation of these lesions demonstrate significant inter-observer variability. Additionally, the significance of detecting nodal melanocytic deposits in theses cases is not clear. Reproducible data with long-term followup for such cases is limited.

As severely atypical spitz nevi have been reported to metastasize, a sentinel lymph node biopsy may be considered if features are present that would lead to a SLN bx in a similar case of melanoma (Piris and Mihm 2009)

21 patients with atypical spitzoid tumors underwent SLN;  6 patients (29%) had positive nodal involvement;  Tumor thickness of 3.4 mm vs. 2.0 mm was significantly associated with nodal involvement (Ann Surg Oncol. 2008 Jan;15(1):302-9. Epub 2007 Nov 14)

A more recent publication (Ludgate et al 2009) of 67 patients treated at the University of Michigan with atypical spitz tumors ("AST") identified 27 (47%) with a positive sentinel lymph node. All 27 pateints with a positive SLN biopsy were alive and diease free with a median follow-up of 43.8 months. Their experience led these investigators to recommend a 1 cm margin about the AST and to involve the patients and families in decision-making about the value of a SLN offered for ASTs with a depth of greater than or equal to 1 mm.  Additionally, thinner ASTs (depth of 0.75 mm) were also offered SLN bx if other adverse features were present. They support this approach by observing the uncertainty of the relevance of deposits in the SLN - but identifying that a negative result is reassuring to the pateints, alleviates distress, and offers the potential that removal of the SLN may possibly have therapeutic value.

Neck Dissection after +'ve SLN biopsy

Ludgate et al (2009) advocate lymphadenectomy after a positive SLN biopsy in a selective fashion based on extent of lymph node involvement and the age of the patient.
       If the +'ve SLN shows >1% involvement of the lymph node surface area (regardless of age), then a subsequent lymphadenectomy is offered - but in a manner that acknowledges controversy. This report from the U of Michigan identified only one additional nonsentinel node was found upon subsequent lymphadenectomy.
       If the +'ve SLN shows <1% of the lymph node involved and the patient is less than or equal to 20 years of age, close observation of the regional nodal basin with serial ultrasound exams is considered. For a similar node, if the patient is >20 years of age, the option of observation is discussed but a "lower threshold for considering" a lymphadenectomy is maintained.

Margins

Given the controversy surrounding atypical spitzoid lesions, variable re-excision margins are employed across the country. According to Situm et al (2008) "Atypical tumors should be excised with margins up to 1 cm"

References:

Ludgate MW, Fullen DR, Lee J, Lowe L, Bradford C, Geiger J, Schwartz J, and Johnson TM: The Atypical Spitz Tumor of Uncertain Biologic Potential.Cancer Feb 1, 2009 pp 631-641
and comment with reply:
Urso c: 'Letter addressing "The Atypical Spitz Tumor of Uncertain Biologic Potential"' Cancer Jan 1 2010 pp257-8.

Lyon VB: The Spitz Nevus: Review and Update  Clin. Plastic Surg 37 (2010) 21-33

Piris A and Mihm MC: Progress in Melanoma Histopathology and Diagnosis. Hematology/Oncology Clinics of North America Volume 23 Issue 3 June 2009.

Situm M, Bolanca Z, Buljan M, Tomas D, and Ivancic M: Nevus Spitz-everlastin diagnostic difficulties -- the reivewe.  Coll Antropol 2008 Oct; 32 Suppl2: 171-6.

Sulit DJ, Guardiano RA, and Krivda S: Classic and atypical Spitz nevi: review of the literature. Cutis. 2007 Feb; 79(2):141-6

Sade S, Al Habeeb A, and Ghazarian D: Spindle cell melanocytic lesions -- part I: an approach to compound naevoidal pattern lesions with spindle cell morphoogy and Spitzoid pattern lesions. J Clin Pathol 2010 63: 296-321