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Brief Report
September 2016

A Symmetric Eczematous Eruption Harboring Thousands of Melanocytic Lesions

Author Affiliations
  • 1Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston
  • 2Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston
  • 3Department of Dermatology, Lahey Hospital and Medical Center, Burlington, Massachusetts
  • 4Department of Medicine, Division of Hematology/Oncology, Massachusetts General Hospital and Harvard Medical School, Boston
JAMA Dermatol. 2016;152(9):1021-1024. doi:10.1001/jamadermatol.2016.1150

Importance  The abrupt appearance of melanocytic lesions is a unique phenomenon that can occur in the setting of eruptive nevi or epidermotropic melanoma metastases.

Objective  To examine the immunohistochemical and genetic mutative features of a novel case of an eczematous reaction followed by the abrupt appearance of melanocytic lesions.

Design, Setting, and Participant  Case report of a 48-year-old woman with no significant medical history who first presented with an eczematous dermatitis on her torso, extremities, and buttocks and who subsequently developed thousands of pinpoint, histologically atypical melanocytic tumors and invasive melanoma within the areas of inflammation.

Main Outcomes and Measures  Immunohistochemical and mutational analyses of the patient’s melanocytic tumors were conducted.

Results  Mutational analysis of the pigmented lesions did not identify any activating mutations in BRAF, PTEN, NRAS, KRAS, and HRAS. Immunohistochemical analyses of 9 biopsied pigmented lesions all showed normal expression of the tumor suppressors p16 and PTEN and no expression of mutated BRAF V600E protein.

Conclusions and Relevance  To our knowledge, this is a previously unreported eruption comprising 2 distinct components: an eczematous reaction and a wave of melanocytic proliferations within the inflammatory regions. Possible explanations for this patient’s condition, include immune stimulation leading to nevogenesis, benign “nevic” metastases, eruptive nevi, and epidermotropic metastatic melanoma.

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