Altered morphology and immunohistochemical characteristics in metastatic malignant melanoma after therapy with vemurafenib

Matthew R. Powell, Daniel J Sheehan, Daniel T Kleven

Research output: Contribution to journalArticle


Metastatic melanoma is traditionally diagnosed using classic morphologic features in addition to immunohistochemical studies. The authors report a case of metastatic malignant melanoma where both morphology and immunohistochemistry were altered after treatment. This 51-year-old patient presented with metastatic melanoma to the brain and axilla. Initially, both metastases showed classic morphology and diffuse staining with the pan-melanoma antibody cocktail. This cocktail is a combination of 3 antibodies commonly used to diagnose melanocytic neoplasms: Melan-A (MART-1), tyrosinase, and HMB-45. In combination, the cocktail is highly sensitive for detecting melanocytic neoplasms and is commonly used to diagnose metastatic melanoma. Her tumor was positive for the BRAF 1799T>A (V600E) mutation, and she was treated with BRAF inhibitor therapy (vemurafenib). However, the axillary tumor recurred after treatment with vemurafenib. The recurrent tumor showed a markedly different morphology and complete loss of staining with the pan-melanoma antibody cocktail. This loss of staining accompanied by the change in morphology was an observation not previously documented after therapy with vemurafenib. This case demonstrates a potential pitfall in the diagnosis of metastatic or recurrent malignant melanoma.

Original languageEnglish (US)
Pages (from-to)e137-e139
JournalAmerican Journal of Dermatopathology
Issue number9
StatePublished - Sep 1 2016



  • BRAF inhibitor therapy
  • changes in recurrent metastatic malignant melanoma
  • malignant melanoma

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Dermatology

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