Acta Dermato-Venereologica issue 50:1 98-1CompleteContent | Page 25

108 CLINICAL REPORT Distinct Patterns and Aetiology of Chromonychia Soo Hyeon BAE, Lee Min YOUNG and Jee-Bum LEE Department of Dermatology, Chonnam National University Medical School, Gwangju, South Korea Abnormal colouring of the nails may be a sign of un- derlying systemic or local disorders. This study in- vestigated the prevalence and causes of chromonychia as a whole, as well as of each subtype. Among 163 patients with chromonychia, trauma was the patho- genesis in up to 20.9% (34/163) of cases. The most common subtype was melanonychia (54.0%; 88/163), followed by leukonychia (23.9%), red (8.6%), green (6.7%), yellow (4.9%) and blue (1.8%) nails. Nail matrix naevus (33.3%; 29/88) was the most common cause of melanonychia, while skin diseases (41.0%; 16/39), such as psoriasis (75%, 12/16) and alopecia areata (18.8%; 3/16), in addition to systemic diseases (33.3%; 13/39) including anaemia (38.5%, 5/13) and chronic renal failure (15.4%; 2/13) were the dominant causes of leukonychia. As chromonychia may be the first or only sign of an underlying disorder, it should alert physicians and patients to the need for a prompt and thorough evaluation. Key words: green nail; leukonychia; melanonychia; nail disco- loration; internal medicine; skin disease. Accepted Sep 13, 2017; Epub ahead of print Sep 13, 2017 Acta Derm Venereol 2018; 98: 108–113. Corr: Jee-Bum Lee, Department of Dermatology, Chonnam National University Medical School, 160 Baekseo-ro, Dong-gu, Gwangju, 61469, South Korea. E mail: [email protected] C hromonychia is an abnormality in the colour of the nail plate or subungual tissue. Common patterns of nail discoloration include black, white, red, green, blue, and yellow dyschromias (1). Interestingly, these nail discolorations can be useful as diagnostic clues to underlying issues, such as skin or systemic diseases, drug exposure, benign or malignant tumours, associated trauma, infections, and exogenous agents (1, 2). As the number of patients with chromonychia visiting derma- tological clinics increases, a diagnostic algorithm for the disease is required. The aim of the present study was to evaluate the epi- demiology and aetiology of chromonychia in Korean patients. While previous reports have focused on each entity individually, especially melanonychia (3, 4), we analysed the prevalence and causes of nail discoloration as a whole as well as for individual entities. In our study, chromonychia was considered a unique category diffe- rent from onychomycosis and therefore fungal infection was excluded. doi: 10.2340/00015555-2798 Acta Derm Venereol 2018; 98: 108–113 METHODS Study design This retrospective study included 163 patients with chromo- nychia who visited Chonnam National University Hospital, Gwangju, South Korea from January 2003 to December 2016. From medical records data were extracted and assessed regarding patients’ demographic characteristics (age and sex), relevant medical history (related systemic or skin diseases and medica- tion), trauma history, physical findings (colour, affected number, site, and pattern), infection (bacterial and fungal cultures) and exogenous agents that were applied. Because of the risk of nail deformity, histopathological examination was only performed for 50 patients when clinical findings were indicative of malig- nant or benign tumour or when patients were anxious about the possibility of malignancy and requested a nail unit biopsy. This retrospective study was approved by the institutional review boards of the participating hospital. Definition and classification of chromonychia Melanonychia is defined as a deposition of brown or black pig- ment in the nail plate from increased pigment production within the nail matrix (5). Patients with melanonychia were subdivided depending on the width of the band: less than 3 mm, 3 mm to less than 6 mm, 6 mm or wider, and total nail plate involvement. Leukonychia is defined as an opaque white discoloration of nail (1). It is classified as true or apparent, depending on whether the origin is in the nail matrix or nail bed. True leukonychia is further divided into total, subtotal, punctate, transverse, and longitudinal subtypes depending on the extent and pattern of involvement. Pseudoleukonychia, in which the abnormality is not derived from the matrix or the nail bed, mainly caused by onychomycosis, was not included in our study. Other patients with chromonychia were categorized into red, green, blue, and yellow nail groups according to nail colour. RESULTS Chromonychia A total of 163 patients with chromonychia visited our department. Their mean age was 43.0  ±  21.9 years. There were 70 males and 93 females, a male:female ratio of 0.75:1. The specific presentations and causes of chromo- nychia are detailed in Table I. Melanonychia Eighty-eight patients (55.3%; 88/163) had melanony- chia, mean age 43.6  ±  23.8 years. There were 34 males and 54 females, a male:female ratio of 0.6:1. The causes of melanonychia are detailed in Table II. The causes This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2018 Acta Dermato-Venereologica.