"Malignant Spitz nevus" in a 2-year-old Japanese child

Smith et al. (1989) have reported a variant of Spitz's nevus with histological atypical features. Despite local lymph node metastases, further metastases were not observed. They proposed the name "malignant Spitz nevus" for this variant. A 2-year-old Japanese girl had a large nodule (27 x 17 mm) surrounded by an indurated erythema over the Achilles tendon. Histologically, it proved to be a melanocytic lesion resembling spindle cell and epithelioid cell nevus (Spitz's nevus) with unusual features; the tumor extended deep into the subcutis, and the mitotic figures deep into the tumor, together with prominent lymphatic vessel invasion by melanocytes. Thus the tumor was aptly termed "malignant Spitz nevus". Flow cytometric analysis of the DNA content revealed a diploid pattern. The child is well 5 years after a wide resection of the tumor. The diploid pattern of the DNA content as well as the good prognosis could support the idea that "malignant Spitz nevus" fits within the spectrum of Spitz's nevus.