Bullous Malignant Melanoma: An Unusual Differential Diagnosis of a Hemorrhagic Friction Blister

Abstract

BACKGROUND: A 66-year-old woman presented to our outpatient clinic with a 3 x 2.5-cm tense, hemorrhagic-appearing bulla on her forefoot. Histopathology and immunohistochemistry confirmed a transtumoral-transepidermal blister formation within an advanced acrolentiginous malignant melanoma (MM). OBJECTIVE: To study bullous malignant melanoma. METHODS: Blistering in MMs represents a rare but clinically important pitfall in clinical differential diagnosis. The blisters are typically due to the disruption of the cohesion between neoplastic cells and keratinocytes, but physical friction may also contribute. RESULTS: Hemorrhagic blistering is, in many cases, a relatively insignificant finding in which frictional forces are imposed. CONCLUSION: The case reported here underscores that in rare cases MMs, particularly if acrally located, can be complicated by hemorrhagic blistering. Because of the life-threatening consequences, one should be aware of this rare differential diagnosis.