Acta Demato-Venereologica 98-2CompleteContent | Page 33

297 Six-month History of a Split Thumbnail: A Quiz Yosuke MAI 1 , Hideyuki UJIIE 1 *, Takashi ANAN 1,3 , Hajime MIYAZAWA 1 , Keisuke IMAFUKU 1 , Kokichi HAMASAKA 2 and Hiroshi SHIMIZU 1 1 Department of Dermatology, Hokkaido University Graduate School of Medicine, North 15 West 7, Kita-ku, Sapporo 060-8638, 2 Hamasaka Skin Clinic, and 3 Sapporo Institute of Dermatopathology, Sapporo, Japan. *E-mail: [email protected] A 38-year-old man presented with a split right thumbnail. He had noticed the nail change 6 months earlier. Physical examination revealed a longitudinal split of the right thumbnail, accompanied by a skin-coloured papule on the proximal nail fold (Fig. 1a). It was initially suspected that a mucous cyst on the proximal nail fold had caused the nail change. The papule was punctured with an 18-gauge needle, but no mucous fluid was observed. A biopsy specimen of the papule on the proximal nail fold showed superficial perivascular lymphocytic inflammatory infiltrates with a focal lichenoid pattern at the dermal–epidermal junction and mild spongiosis with a few necrotic keratinocytes in the epidermis (Fig. 1a–c). In addition, similar lymphocytic infiltrates were observed around the nail matrix (Fig. 1d). Notably, the eccrine glands and ducts were also involved (Fig. 1e). What is your diagnosis? See next page for answer. Fig. 1. Clinical presentation: a longitudinal split of the right thumbnail with a skin-coloured papule on the proximal nail fold. (a) Dotted circle indicates the biopsy site on the papule of the proximal nail fold. Arrow represents the longitudinal section. Histopathology of the proximal nail fold and around the nail matrix. (b) The dense lymphocytic infiltration in the proximal nail fold (square) and around the nail matrix (dotted square) (haematoxylin and eosin staining, original magnification ×40). (c) Focal perivascular lymphocytic infiltrates and mild spongiosis with a few necrotic keratinocytes (original magnification ×200, corresponding to the square in Fig. 1b). (d) Lymphocytic infiltrates around the nail matrix (original magnification ×200, corresponding to the dotted square). (e) Eccrine gland involvement in another section (original magnification ×200). QUIZ SECTION This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2018 Acta Dermato-Venereologica. doi: 10.2340/00015555-2817 Acta Derm Venereol 2018; 98: 297–298