TY - JOUR T1 - Longitudinal melanonychia JF - BMJ Case Reports DO - 10.1136/bcr-2015-213459 VL - 2015 SP - bcr2015213459 AU - Kamran Khan AU - Arun A Mavanur Y1 - 2015/12/10 UR - http://casereports.bmj.com/content/2015/bcr-2015-213459.abstract N2 - An otherwise healthy 13-year-old boy was noted to have a discolouration arising from the nail bed of the left thumb. The lesion exhibited brisk linear transformation since it was initially noticed 4 months prior. There was no family history of melanoma, and he was not taking any medications. Examination confirmed a symmetrically pigmented lesion in the subungual area of the left thumb, measuring 4 mm in width (figure 1). There was extension of the black pigmentation into the proximal nail fold (Hutchinson's sign), measuring 1 mm in length. A 6 mm punch was used to excise a circular segment of the nail, followed by a 4 mm punch biopsy of the subungual area (figure 2 … ER -