Metastatic melanoma with balloon cell changes

Abstract

Two cases of balloon cell malignant melanoma are presented. Attention is drawn to the diagnostic difficulties which may be encountered in distinguishing these lesions from other clear cell tumors. Ultrastructurally, the cytoplasm of these balloon cells is characterized by an absence of premelanosomes and melanosomes, and by the presence of numerous, large membrane-bound vesicles. Balloon cells show defective melanogenesis, and the cytoplasmic vesicles may represent grossly dilated smooth endoplasmic reticulum.