A case of balloon cell melanoma

Balloon cell melanoma, an uncommon histopathological variant of malignant melanoma was first described by Gardner and Vazquez in 1970. This is histopathologically characterized by the presence of balloon cells with varying sizes and atypical nuclei. A 45-year-old man presented with asymptomatic, solitary, dome shaped, 1.5 cm-diameter black nodule on the left upper arm for 7 years. Histopathologically, lobulated tumor mass revealed copious melanin pigments and many balloon cells with clear cytoplasm, atypical nucleic and variable size. Immunohistochemically the tumor mass showed positive reaction to S-100 protein and HMB 45 staining. Chest CT, MRI for the extremities, bone scan, bone marrow biopsy and routine laboratory tests were within normal limit or negative. Gallium scan showed increased density only on the skin lesion. There was no evidence of lymphadenopathy and metastasis. We herein report a typical case of balloon cell melanoma, which developed primarily on the skin.