ORIGINAL ARTICLE Typical and atypical dermoscopic presentations of dermatofibroma A. Ferrari, 1, * G. Argenziano, 2 P. Buccini, 1 C. Cota, 3 I. Sperduti, 4 P. De Simone, 1 L. Eibenschutz, 1 V. Silipo, 1 I. Zalaudek, 2 C. Catricala ` 1 1 Department of Oncologic Dermatology, San Gallicano Dermatological Institute, Rome, Italy 2 Dermatology Unit, Medical Department, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy 3 Laboratory of Pathology, San Gallicano Dermatologic Institute, Rome, Italy 4 Unit of Biostatistics, Regina Elena National Cancer Institute, Rome, Italy *Correspondence: A. Ferrari. E-mail: angiferrari@libero.it Abstract Background Dermatofibroma is a common skin neoplasm that is usually easy to recognize, but in some cases its differentiation from melanoma and other tumours may be difficult. Objective To describe the dermoscopic features of dermatofibromas, with special emphasis on the characteristics of atypical patterns, and to calculate pattern frequency according to the patients age and gender, anatomical site and histopathological subtype. Methods Two groups of patients were consecutively seen, one with dermatofibromas that were surgically excised because of clinically and / or dermoscopically equivocal aspects or following patient request, and another with non- equivocal dermatofibromas. Each lesion was scored for previously reported global dermoscopic patterns and for additional features. Results A typical pattern was observed in 92 of 130 (70.8%) lesions, whereas an atypical pattern, that we named the ‘non Dermatofibroma (DF)-like’ pattern, was seen in 38 of 130 (29.2%). Atypical dermatofibromas showed features reminiscent of different conditions, such as melanoma in 21(16.2%) cases, vascular tumour in six (4.6%), basal cell carcinoma in five (3.8%), collision tumour in three (2.3%) and psoriasis in three (2.3%). A significant association was found between the ‘melanoma-like’ pattern / ‘vascular tumour-like’ pattern and males, whereas a trend was observed between the above-mentioned patterns and hemosiderotic / aneurysmal DFs. ‘Peripheral pigment network and central white scar-like patch’ pattern was found associated with females and classic histopathological variant of DF. Conclusion Dermatofibromas may display different morphological faces. The typical dermoscopic patterns allow a confident diagnosis, whereas a full surgical excision is always recommended in all doubtful cases. Received: 23 May 2012; Accepted: 19 September 2012 Conflict of interest None declared Founding sources None reported Introduction Dermatofibroma (DF) is a common, benign dermal proliferation, clinically appearing as a firm, occasionally pigmented papule, pla- que or nodule, with a smooth or keratotic surface and variable size (up to 2 cm). Multiple DFs and giant DFs are also reported in the literature. The dimpling of the skin by lateral compression can produce the well-known ‘dimple-sign’ that is, however, not unique to DF. Histopathologically a number of variants are recognized, including lichenoid DF, ulcerated DF, keloidal DF, cellular DF, lip- idized DF, atrophic DF, hemosiderotic / aneurysmal DF and fibrous histiocytoma. Melanoma is a crucial clinical differential diagnosis, but other conditions, such as basal and squamous cell carcinoma, morphea, neurofibroma, localized lipoatrophy and anetoderma are included. 1–6 Dermoscopy is a standard procedure whose benefits in the diag- nosis and management of pigmented skin tumours have been lar- gely proven in the last years. 7–12 Besides a few case reports and studies involving a relatively low number of patients, 13–18 the ª 2012 The Authors JEADV 2013, 27, 1375–1380 Journal of the European Academy of Dermatology and Venereology ª 2012 European Academy of Dermatology and Venereology DOI: 10.1111/jdv.12019 JEADV