Tapioca melanomas of the iris: immunohistology and report on two cases

Background: Tapioca-like tumors are rare, and their benign or malignant nat ure is obscure without histological work-up. We report on the clinical and histological features of different types of tumors in two patients, Case re port: Two patients aged 17 and 45 years presented with brownish iris masses increasing in size. Full-thickness en bloc excision of melanocytic tumors (5.5 mm and 7.0 mm in diameter) was carried out. Histological work-up revea led a nevus cell nevus in the young patient and an epithelioid malignant me lanoma in the middle-aged patient evolving from the ciliary body. Staining for HMB-45 was marked in both tumors, for S-100 low in the nevus and marked in the melanoma, and for p53 negative in the nevus and positive in the mel anoma, Ki67 stains were negative, Conclusion: We propose that excision of a nteriorly located pigmented tumors that increase in size is indicated in or der to determine whether they are benign or malignant. In these case report s, tapioca-like tumors include a benign and a malignant entity. To our know ledge, a nevus cell nevus presenting as a tapioca-like tumor has not previo usly been described. Curative surgery and histological and immunohistologic al evaluation are required to characterize the malignant potential of these tumors and the prognosis.