Malignant Melanoma Presenting as a Parotid Mass in a Middle-aged Woman with Metastasis to the Breast

Introduction: Malignant melanomas of the parotid gland are relatively uncommon and usually seen as metastases from cutaneous or mucous sites of the head and neck region. Some malignant melanomas may metastasize before they regress. Therefore, identifying the primary origin of metastatic melanoma is sometimes difficult. Furthermore, metastasis to the breast from an extramammary site is uncommon and challenging. It may present as a well-defined rounded mass that histopathologically mimics the various architecture and cellular phenotypes. In addition, the immunohistochemical stains of some metastatic melanomas are equivocal and challenging. Case Presentation: We presented a case of parotid gland malignant melanoma in a 42-year-old woman with metastasis to the breast in a short interval. Biopsy of parotid and breast lesions showed loss of immune-reactivity for several melanoma markers and was initially considered as malignant peripheral nerve sheath tumor and primary breast tumor, respectively. Conclusions: This case highlights the importance of obtaining past clinical history in surgical pathology cases to make a correct diagnosis. It also enhances our understanding regarding malignant melanoma as a mysterious tumor with various morphology and immunophenotype.