Metastatic Malignant Melanoma of the Inguinal Lymph Node with Unknown Primary Lesion

Figure 2

(a) Metastatic melanoma replacing a lymph node with a thin rim of residual lymphocytes (far right) H&E 5x. (b) The malignant cells are strongly positive for Melan A, (c) positive for HMB45, and (d) negative for cytokeratin AE1/AE3 (IHC, 5x). Although this staining pattern could be seen in benign and malignant melanocytes, its presence in a lymph node indicates metastasis.

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