Chondroid melanoma metastatic to lung and skin showing SOX-9 expression: a potential diagnostic pitfall

Melanoma is a malignant neoplasm that shows multiple morphological appearances resembling other tumors and therefore may generate diagnostic pitfalls. In cases of metastatic melanoma, when the primary skin lesion has gone undiscovered or has not been brought to the attention of the clinician or pathologist, the metastatic lesion can be misdiagnosed as sarcoma, carcinoma, or lymphoma. Melanomas with differentiation toward mesenchymal elements are particularly perilous in this regard. Here, the authors report a case of metastatic melanoma that was misdiagnosed as extraskeletal myxoid chondrosarcoma. This case highlights the potential diagnostic pitfall posed by metastatic melanoma with chondroid matrix and SOX-9 expression.