Novel Histopathologic Features of Median Canaliform Dystrophy.

Median canaliform dystrophy (MCD) of Heller is a rare nail disorder characterized by a median split and obliquely running furrows of the nail plate, often presenting in a "fir-tree" pattern. While its pathogenesis remains poorly understood, proposed etiologies include habitual trauma, iatrogenic causes, and familial predisposition. Diagnosis is generally made by clinical evaluation. There is a paucity of data regarding the histopathology of MCD. Herein, we present two cases of MCD with novel histopathologic features, broadening the understanding of the pathophysiology and potential therapeutic options for this condition. In Case 1, histopathologic evaluation revealed mild spongiosis, suggesting an inflammatory etiology. Case 2 demonstrated distinctive acantholysis. These findings suggest that MCD encompasses a spectrum of histopathologic changes. Our report contributes to the limited histopathologic characterization of MCD.