RESUMEN
BACKGROUND: The clinical diagnosis of dermatofibroma is commonly easy. However, the differentiation of dermatofibroma from other cutaneous tumours is difficult in some instances, primarily in atypical cases and rare variants. Haemosiderotic dermatofibroma is a variant composed of numerous small vessels, extravasated erythrocytes and intra- and extracellular haemosiderin deposits. Aneurysmal dermatofibroma is a variant composed of large, blood-filled spaces without endothelial lining. Some authors consider that haemosiderotic dermatofibroma is an early stage in the development of aneurysmal dermatofibroma. The clinical differential diagnosis of haemosiderotic or aneurysmal dermatofibroma must include melanoma and other melanocytic tumours, vascular neoplasms, adnexal tumours and nonspecific cysts. Dermoscopy improves the diagnostic accuracy in pigmented and nonpigmented skin lesions. OBJECTIVES: To evaluate specific dermoscopic criteria. METHODS: Dermoscopic examination (using the DermLite Foto; 3Gen, LLC, Dana Point, CA, U.S.A.) of six patients with haemosiderotic or aneurysmal dermatofibromas was performed to evaluate specific dermoscopic criteria. RESULTS: A multicomponent pattern with a central bluish or reddish homogeneous area in combination with white structures and a peripheral delicate pigment network along with vascular structures was noted in five of six lesions. CONCLUSIONS: This dermoscopic pattern yielded the diagnosis of haemosiderotic or aneurysmal dermatofibroma in most cases. However, this multicomponent pattern may present in some melanomas and although it is useful in determining a clinical diagnosis of aneurysmal dermatofibroma, it may not be specific to this entity.