Atypical Multinail Median Canaliform Dystrophy of Heller with Toenail Involvement: A Case Report

Purpose Median canaliform dystrophy of Heller (MCDH) is a rare nail matrix disorder typically affecting one or both thumbnails. Multinail involvement, including toenails, is rarely reported. We describe a case with atypical multi-digit involvement to broaden the recognized clinical spectrum. Methods A 29-year-old male underwent dermatologic evaluation for chronic, asymptomatic nail deformities of both thumbnails and the left great toenail. Diagnosis was made clinically based on characteristic morphology after systematically excluding onychomycosis, habit-tic deformity, and inflammatory nail disorders. Results Examination revealed central longitudinal canals with symmetric oblique lateral ridging forming a fir-tree pattern. Periungual tissues were normal, and there was no history of trauma, manipulation, systemic disease, or medication exposure. A clinical diagnosis of MCDH was established. The patient was managed conservatively with reassurance and advice to avoid microtrauma. At six-month follow-up, nail changes were stable and asymptomatic; the patient reported understanding the benign nature of the condition. Conclusions This case demonstrates an uncommon idiopathic presentation of MCDH involving bilateral thumbnails and a toenail. Awareness of such atypical presentations can prevent misdiagnosis, unnecessary testing, and inappropriate interventions.