The multiple faces of atypical dermatofibromas: Uncommon dermoscopic patterns

Dermatofibromas are very common cutaneous lesions with a predilection for limbs of young or middle-aged adults. Although the clinical diagnosis is usually straightforward, dermoscopy is a valuable diagnostic tool to increase the diagnostic accuracy of these lesions. The classic dermoscopic pattern of dermatofibromas consists in a white central scar-like patch surrounded either by erythema or delicate pigment network depending on the individual’s skin phototype (1). However, dermatofibromas show a considerably variability of dermoscopic patterns representing a diagnosis challenge even for expert dermoscopists (2, 3). We report fifteen cases of atypical dermatofibromas, which were clinically diagnosed as basal cell carcinoma, Spitz naevus and malignant melanoma. All lesions were excised and histologically confirmed as dermatofibromas. Interestingly, most of these atypical lesions were nodular and located on the back. Uncommon dermoscopic patterns of dermatofibroma include multiple colours, polymorphic blood vessels, white shiny lines on a pinkish background, negative pigment network with dotted vessels, central white patch with prominent peripheral linear vessels and homogeneous blue colour with shiny white lines in the aneurysmatic variant. Histologic confirmation is mandatory in atypical dermatofibromas or infrequent dermoscopic patterns to exclude another benign or malignant tumours. Key Words: Dermatofibroma, atypical, Spitz, melanoma, basal cell carcinoma, dermoscopy 1. Zaballos P, Puig S, Llambrich A, Malvehy J. Dermoscopy of dermatofibromas: a prospective morphological study of 412 cases. Archives of dermatology. 2008 Jan;144(1):75-83. PubMed PMID: 18209171. 2. Espasandin-Arias M, Moscarella E, Mota-Bucard A, Moreno-Moreno C, Lallas A, Longo C, et al. The dermoscopic variability of dermatofibromas. Journal of the American Academy of Dermatology. 2015 Jan;72(1 Suppl):S22-4. PubMed PMID: 25500030. 3. Kilinc Karaarslan I, Gencoglan G, Akalin T, Ozdemir F. Different dermoscopic faces of dermatofibromas. Journal of the American Academy of Dermatology. 2007 Sep;57(3):401-6. PubMed PMID: 17560684.