title: The atypical Spitz tumor of uncertain biologic potential: a series of 67 patients from a single institution.
abstract: BACKGROUND
  Atypical Spitz tumors (AST) are rare spitzoid melanocytic proliferations with an uncertain malignant potential. ASTs have overlapping features of both Spitz nevi and spitzoid melanoma, and consequently generate controversy with diagnosis and management. Sentinel lymph node biopsy (SLNB) has been proposed as a possible means to gain additional insight into the true biologic potential of these tumors; however, previous reports on the use of SLNB in ASTs have been limited by small numbers of patients and short durations of follow-up.
  
  
  METHODS
  The authors extracted data from their institution's prospective melanoma database, collected between 1994 and 2007, for all patients with ASTs of uncertain biologic potential. They reviewed the clinical features of these patients, including the sentinel lymph node status, and the histological features of the tumors.
  
  
  RESULTS
  A total of 67 patients with ASTs were identified, with a median age of 23.7 years. The mean depth was 2.4 mm. Of these, 57 had a SLNB performed, with 27 (47%) having a positive sentinel lymph node. SLNB-positive cases had a significantly lower mean age than SLNB-negative cases (17.9 vs 28.7 years; P = .013); however, no other significant differences were observed. All 27 patients with a positive SLNB were alive and disease free with median follow-up of 43.8 months. One patient who did not receive a SLNB developed recurrent disease with regional and distant metastases.
  
  
  CONCLUSIONS
  ASTs do not appear to behave like conventional melanoma. There is a high incidence of microscopic lymph node deposits in SLNBs, but despite this finding, patients have a favorable prognosis. Our findings raise several questions regarding the malignant potential of ASTs, and the role of SLNB in their management.
authors.affiliation: Department of Dermatology, University of Michigan Medical School and Comprehensive Cancer Center, Ann Arbor, Michigan 48109, USA. mathewlu@med.umich.edu
authors.forename: Mathew W
authors.initials: MW
authors.lastname: Ludgate
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Fullen
authors.forename: Julia
authors.initials: J
authors.lastname: Lee
authors.forename: Lori
authors.initials: L
authors.lastname: Lowe
authors.forename: Carol
authors.initials: C
authors.lastname: Bradford
authors.forename: James
authors.initials: J
authors.lastname: Geiger
authors.forename: Jennifer
authors.initials: J
authors.lastname: Schwartz
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Johnson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008545:Melanoma / Q000473:pathology*; D008875:Middle Aged; D018332:Nevus, Epithelioid and Spindle Cell / Q000473:pathology*; D011379:Prognosis; D021701:Sentinel Lymph Node Biopsy; D012878:Skin Neoplasms / Q000473:pathology*; D055815:Young Adult