Nodular malignant melanoma with Spitz nevus-like pathological features finally confirmed by the pathological feature of the sentinel lymph node

The clinical and histopathological similarities of nodular melanoma and Spitz nevus currently still make a definitive diagnosis difficult. We report here a case of nodular melanoma that was extremely difficult to diagnose both clinically and histopathologically. The primary tumor was a blackish nodule on the scalp and biopsy was performed for pathological diagnosis. Although our first impression was malignant melanoma, we asked two dermatopathologists for second opinions; however, one diagnosed a melanoma and the other a Spitz nevus. Faced with this clinical dilemma, an operation was performed with sentinel node biopsy. Only one sentinel node suggested a metastasis. Histopathological diagnosis to establish whether it was a melanoma metastasis or nodal nevi was also difficult, and we again asked for second opinions from another dermatopathologist in the USA. According to its clinical course and the histopathology of the sentinel lymph node with additional immunohistochemistry, this case was finally diagnosed as a nodular melanoma (T4aN1aM0, stage IIIA). To date, the patient has been given five courses of chemotherapy at 6-month intervals, with no local recurrence or distant metastases so far.