Final Diagnosis -- Atypical melanocytic neoplasms of uncertain malignant potential


Regardless of the wording of the rendered diagnoses, it was recommended that all these lesions be re-excised and that a consideration be given to sentinel lymph node biopsy (SLNB).


The neoplasms described above belong to a subset of problematic and diagnostically challenging melanocytic neoplasms variably labeled as: as atypical Spitz tumor, atypical Spitz nevus, Spitz-like lesion in the borderline category of indeterminate malignant potential, and diagnostically controversial spitzoid melanocytic tumors [1], as well as atypical Spitzoid neoplasms, severely atypical melanocytic neoplasms (tumors), and would also be classifiable under the category of "minimal deviation" or "nevoid" melanoma.. These lesions simultaneously exhibit some features of Spitz nevus and Spitz-like melanoma.

The cases discussed above have some features of Spitz nevus:

The same neoplasms also have some atypical features:

The biologic behavior of these atypical spitzoid melanocytic neoplasms has not been clearly elucidated. Experts often regard these lesions as having an indeterminate malignant potential. Therefore most dermatologists would recommend treating these neoplasms in a similar fashion to melanomas advising wide re-excision and SLNB depending on the measured depth of "possible" invasion (from the surface of epidermis to the bottom of the atypical melanocyte component). However, this is the problematic area, as the accepted prognostic markers (namely: Breslow's and Clark's depths and surface ulceration) do not apply well with the neoplasms that do NOT arise at the dermo-epidermal junction [8]).

Many ancillary diagnostic techniques have been used to try to discriminate benign lesions from malignant melanocytic.

However, currently, there is no single technique that unequivocally discriminates among these borderline lesions.

Because the status of the regional lymph nodes is a powerful predictor of overall survival for melanoma, SLNB is a useful adjunct in the management of histologically difficult melanocytic lesions.[6] In one recent study, 8 of 18 patients (44%) with atypical spitzoid melanocytic lesions were reclassified as melanoma based on positive SLNB results [1]. In another study 5 of 10 (50%) of diagnostically controversial spitzoid tumors metastasized to SLNs [7].

Our patient underwent SLNB of axillary and groin lymph nodes and there was no metastatic disease identified in any of the specimens. In addition to the wide re-excisions, he also received Interferon alpha2b therapy. The last three neoplasms described above were excised while the patient was receiving this therapy.


  1. Su LD, Fullen DR, Sondak VK, Johnson TM, Lowe L. Sentinel lymph node biopsy for patients with problematic spitzoid melanocytic lesions: a report on 18 patients. Cancer 2003 Jan 15;97(2):499-507.
  2. Li LX, Crotty KA, McCarthy SW, Palmer AA, Kril JJ. A zonal comparison of MIB1-Ki67 immunoreactivity in benign and malignant melanocytic lesions. Am J Dermatopathol. 2000; 22: 489-495.
  3. Duncan LM, Deeds J, Cronin FE, et al. Melastatin expression and prognosis in cutaneous malignant melanoma. J Clin Oncol. 2001; 19: 568-576.
  4. De Wit PE, Kerstens HM, Poddighe PJ, Van Muijen GN, Ruiter DJ. DNA in situ hybridization as a diagnostic tool in the discrimination of melanoma and Spitz naevus. J Pathol. 1994; 173: 227-233.
  5. Bastian BC, Wesselmann U, Pinkel D, LeBoit PE. Molecular cytogenetic analysis of Spitz nevi shows clear differences to melanoma. J Invest Dermatol. 1999; 113: 1065-1069.
  6. Kelley SW, Cockerell CJ. Sentinel lymph node biopsy as an adjunct to management of histologically difficult to diagnose melanocytic lesions: a proposal. J Am Acad Dermatol. 2000
  7. Lohmann CM, Coit DG, Brady MS, Berwick M, Busam KJ. Sentinel lymph node biopsy in patients with diagnostically controversial spitzoid melanocytic tumors. Am J Surg Pathol. 2002; 26: 47-55.
  8. Balch CM, Soong SJ, Gershenwald JE, Thompson JF, Reintgen DS, Cascinelli N, Urist M, McMasters KM, Ross MI, Kirkwood JM, Atkins MB, Thompson JA, Coit DG, Byrd D, Desmond R, Zhang Y, Liu PY, Lyman GH, Morabito A.: Prognostic factors analysis of 17,600 melanoma patients: validation of the American Joint Committee on Cancer melanoma staging system. J Clin Oncol. 2001 Aug 15;19(16):3622-34.

Contributed by Muammar Arida, MD and Drazen M. Jukic, MD, PHD.

Case IndexCME Case StudiesFeedbackHome