ActaDV ActaDV Advances in dermatology and venereology Acta Dermato-Venereologica QUIZ SECTION Acta Derm Venereol 2017; 97: 1261–1262 This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2017 Acta Dermato-Venereologica. doi: 10.2340/00015555-2740 1261 An otherwise healthy man in his 60s was concerned about an asymptomatic nodule on his left arm that showed rapid growth (Fig. 1A). The patient stated that it had been gro- wing for approximately 2 months, and he was certain of the absence of any prior lesion at that site. Clinical examina- tion revealed a 1-cm, firm, exophytic nodule, with colour ranging from pink to blue, with well-defined and regular borders, indolent and homogeneously hard on palpation, seated on photo-damaged skin. No ulceration or peripheral macular pigmentation was observed to extend beyond the base of the lesion. Dermoscopy revealed homogeneous blue pigmentation, patchy brown, scattered pigmentation and hairpin-like vessels at the borders, sometimes extending into whitish structureless areas (Fig. 1B). An excisional biopsy specimen was obtained showing a well-circumscribed and asymmetrically pigmented dermal nodule composed of variably pigmented basaloid cells, admixed with numerous dendritic melanocytes (Fig. 1C). What is your diagnosis? See next page for answer. A Pinkish-Blue Exophytic Nodule on the Arm of an Elderly Man: A Quiz Calogero PAGLIARELLO 1 , Ignazio STANGANELLI 2 , Roberto RICCI 3 , Claudio FELICIANI 4 and Sergio DI NUZZO 4 1 Division of Dermatology, UO Multizonale ’Santa Chiara’ Hospital, Trento, 2 Skin Cancer Unit IRCCS IRST, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori, Meldola (FC), 3 Anatomic Pathology Unit, University Hospital of Parma, 4 Section of Dermatology, Department of Medicine and Surgery, Parma Medical School, via Gramsci 14, IT-43100 Parma, Italy, Italy. E-mail: calogero.pagliarello@libero.it Fig. 1. (A) Clinical image. (B) Dermoscopy of the lesion. (C) Histopathological picture, haematoxylin-eosin. Original magnification ×4.