Acta Dermato-Venereologica 97-6 97-6CompleteContent | Page 30

765 SHORT COMMUNICATION Fungal Melanonychia: Ungual Phaeohyphomycosis caused by Botryosphaeria dothidea Hiromitsu NOGUCHI 1,2 , Masataro HIRUMA 2 , Tadahiko MATSUMOTO 2 , Rui KANO 3 , Masaru TANAKA 4 , Takashi YAGUCHI 5 , Kazuhiro SONODA 6 and Hironobu IHN 7 Noguchi Dermatology Clinic, 1834-1 Namazu, Kashima-machi, Kamimashiki-gun, Kumamoto 861-3101, 2 Ochanomizu Institute for Medical Mycology and Allergology, Tokyo, 3 Department of Pathobiology, Nihon University School of Veterinary Medicine, Kanagawa, 4 Department of Dermatology, Tokyo Women’s Medical University Medical Center East, Tokyo, 5 Division of Bio-resources, Medical Mycology Research Center, Chiba University, Chiba, 6 Division of Internal Medicine, Yatsuda Hospital, Kumamoto, and 7 Department of Dermatology and Plastic Surgery, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan. E-mail: [email protected] 1 Accepted Mar 15, 2017; Epub ahead of print Mar 15, 2017 The phaeoid fungus Neoscytalidium dimidiatum and a dermatophyte Trichophyton rubrum are the most fre- quently isolated agents causing fungal melanonychia, followed by the phaeoid fungi of the genera Alternaria and Exophiala (1, 2). Phaeohyphomycosis is an um- brella term describing infections in humans and other animals characterized primarily by the development of dark-coloured hyphae that are caused by phaeoid fungi. The term “phaeohyphomycosis” encompasses broad mycotic infections, regardless of the site of the lesion; the pattern of tissue response, granuloma, or abscess; or the taxonomy of the aetiological agents (3). We describe here a classic example of ungual phaeohyphomycosis. CASE REPORT An 82-year-old retired Japanese farmer with chronic heart failure and hemiparesis noticed a black-pigmented area on his right thumbnail that had been present for 6 months. His internist (KS) considered the possibility of malignant melanoma. Upon presen- tation in February 2016, the nail was thickened and rough with a greyish-white surface, and black pigmentation was observed from its centre to the proximal side. Hutchinson’s sign was not observed (Fig. 1a). The discoloured area accounted for 91% of the entire nail plate (Image J version 1.48; National Institutes of Health, Bethesda, MD, USA). Dermoscopy (Handyscope connected to an iPhone 6, FotoFinder, Bad Birnbach, Germany) revealed that the distal three-fifths of the nail plate showed a whitish scaly area with random reflection and intermingling irregular black dots, while the proximal one-fifth showed a normal nail plate. Between these Fig. 1. Clinical characteristics of the thumb nail. (a) Clinical image at presentation. Melanonychia without Hutchinson’s sign. (b) Dermoscopic image showing a black homogenous area and coarse granules proximally. (c) Findings after 4 months of topical application of 10% efinaconazole solution. The opacity ratio decreased from 91% to 32% during that time. 2 areas, a black homogenous area and a partially grey granular area were observed (Fig. 1b). Direct microscopy revealed branching brown septate hyphae (Fig. 2a), and haematoxylin and eosin and periodic acid-Schiff staining revealed black septate hyphae in the nail plate. The thick cell wall appeared to be double contoured (Fig. 2b). Plate culture on potato dextrose agar after 7 days at 30°C showed a greyish-white woolly colony with coal-black pigmentation on the reverse (Fig. 2c, d). Slide culture showed pigmented broad and unpigmented narrow branching hyphae and intercalary and acropetal chlamydoconidia measuring up to 40 μm (Fig. 2e). The sequence of the internal transcribed spacer 1 region of the ribosomal RNA gene from the nail and isolate had 99% homology to the Botryosphaeria dothidea type strain CBS 115476 (accession: KF766151) (4). Based on the morphological characteristics and gene analysis results, we diagnosed the patient with ungual phaeohyphomycosis due to B. dothidea (Moug. ex Fr.) Ces. & De Not. The minimum inhibitory concentrations for the isolate were as follows: amphotericin B, 0.25 µg/ml; efinaconazole (EFCZ), 1.0 µg/ml; fluconazole, > 64 µg/ml; 5-fluorocytosine, 2 µg/ml; itraconazole, > 16 µg/ml; micafungin, 0.25 µg/ml; miconazole, 0.25 µg/ml; terbinafine, 0.5 µg/ml; and voriconazole, 0.03 µg/ml. Nail opacity was reduced to 74% and 32% of the nail surface after 1 and 4 months, respectively, of topical application of 10% EFCZ solution (Fig. 1c). The discoloration disappeared with negative conversion of the fungi after 7 months. The patient showed no recurrence of fungal infection during a 3-month follow-up, as of December 2016. Fig. 2. Mycologic characteristics. (a) Direct microscopic examination revealed branching black hyphae (KOH preparation, original magnification ×400). (b) Septate black hyphae in the nail plate (periodic acid-Schiff staining ×400). (c, d) Plate culture showed a greyish-white woolly colony with a coal-black pigmentation on the reverse. (e) Slide culture showed pigmented broad and unpigmented narrow hyphae and chlamydoconidia. (Lactophenol Cotton Blue staining ×400). This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2017 Acta Dermato-Venereologica. doi: 10.2340/00015555-2647 Acta Derm Venereol 2017; 97: 765–766