ABSTRACT
Balloon cell malignant melanoma (BCMM) is an extremely rare malignant melanoma subtype. The clinical appearance of BCMM varies: it may be nodular, ulcerated, polypoid, papillomatous and often nonpigmented, and until now, only a few case reports described its dermoscopic pattern. It is typically a tumor of older patients.
Balloon cells may present as a focal change in a melanoma or less often affect the tumor diffusely.
Balloon cells are epithelioid, with abundant eosinophilic granular or foamy cytoplasm. Nuclei are often hyperchromatic and irregular, although sometimes they have a vesicular appearance. The cells typically label with the usual melanoma markers, such as S100 protein and HMB-45. The cause of the balloon cell change is uncertain but may represent a manifestation of melanosome degeneration. The differential diagnosis is broad, and clinicopathologic correlation may play a critical role in achieving the correct diagnosis.
