Occupation-related pigmented macules on the sole with parallel-ridge pattern on dermatoscopy M. Tanioka, Y. Matsumura, A. Utani, M. Tanaka* and Y. Miyachi Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto, Japan; and *Department of Dermatology, Tokyo Women’s Medical University Medical Center East, Tokyo, Japan doi:10.1111/j.1365-2230.2008.03134.x Summary A 27-year-old man presented with pigmented macules on the right sole, which showed a parallel-ridge pattern on dermatoscopy. His work for a chemical company involved handling para-phenylenediamine. Histological examination of a biopsy from a lesion did not find any proliferation of atypical melanocytes. Shaving the cornified layer of the lesions with a surgical knife resulted in the disappearance of macules. We speculate that para-phenylenediamine on the sole of the patient’s work boot might have become blotted to the cornified layer of the cutis. This report adds a new occupation-related differential diagnosis for skin diseases showing a parallel-ridge pattern on dermatoscopy. Dermatoscopic examination is a recent advance in the diagnosis of palmoplantar pigmented lesions. A parallel- ridge pattern (PRP) is one of the most important dermatoscopic findings, which is seen in macular portions of malignant melanoma (MM) on acral volar skin. 1 The sensitivity and specificity of the PRP in MM was found to be 86% and 99%, respectively. 2 We present a case of occupation-related pigmented macules on the sole with PRP on dermatoscopy. A 27-year-old man was referred to our department for evaluation of pigmented macules on the right sole. His medical history was unremarkable. On physical examination, he was found to have asymmetrical pigmented macules in an area 50 · 30 mm in size on the right sole and small macules, 1–2 mm in size, on the left sole (Fig. 1). The macules showed colour variegation, and were accompanied by small satellite lesions. There were no pigmented macules on any other body surface including the hands and lips. Dermatoscopic examination found a PRP in all macules (Fig. 2). The patient worked for a chemical company and handled para-phenylenediamine in a well-equipped laboratory. His coworkers had not reported similar pigmented macules on their skin. The finding of a PRP strongly suggested that the lesions might be MM, although there was little colour variation in each macule. In addition, there were no other dermatoscopic signs of melanoma, such as a fibrillar pattern, irrespec- tive of the pressure-loaded area. Macroscopic examination of a skin biopsy taken from a macule found pigmentation in the cornified layer by macroscopic examination. Histological examination did not find any atypical melanocytic proliferation. There- fore, we shaved the cornified layer of other lesions with a surgical knife, resulting in disappearance of the macules (Fig. 3). In Japan, the incidence of MM has markedly increased over recent years. Compared with white patients with MM in western countries where superficial spreading melanoma is the most frequent subtype, acral lentigi- nous melanoma (ALM) is the most prevalent clinical phenotype in nonwhite populations and accounts for about half of MM cases in Japan. 3–5 In addition, approximately half of Japanese ALM cases occur on the sole of the foot. 3–5 Therefore, it is important to distinguish MM from benign skin lesions when pig- mented macules are present on the sole. One of the recent advances in dermatoscopy is an understanding of Correspondence: Dr Miki Tanioka, Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan. E-mail: mtanioka@kuhp.kyoto-u.ac.jp Conflict of interest: none declared. Accepted for publication 14 July 2008 Clinical dermatology • Concise report Clinical and Experimental Dermatology Ó 2009 The Author(s) Journal compilation Ó 2009 British Association of Dermatologists • Clinical and Experimental Dermatology, 34, e31–e33 e31