RESUMO
Introduction: Median canaliform dystrophy of Heller (MCDH) is a rare nail disorder that typically affects the thumbnails and is characterized by transverse ridges radiating from a paramedian canal or split in the nail plate, bearing resemblance to a fir tree. Case Report: We report here a case of a 60-year-old woman of rural origin, a carpet weaver, with no specific medical history. She was referred due to nail dystrophy on her thumbs that had been progressing over the last 10 years. Clinical examination revealed the presence of a midline splitting with a fir tree-like appearance of ridges angled backwards and normal cuticle. These lesions were symmetrically present on both thumbnails and the big toe nail. Based on this presentation, a diagnosis of Heller's canaliform dystrophy was established. Conclusion: Although the pathophysiology of MCDH remains unclear, proposed mechanisms include keratinocyte adhesion abnormalities, genetic predisposition, and inflammation within the nail matrix. Risk factors encompass medications like oral retinoids and self-inflicted trauma, as seen in repetitive cuticle manipulation. In this case, the patient's nail dystrophy resulted from chronic local microtrauma due to her carpet weaving occupation, suggesting certain manual professions may contribute to MCDH development.
