The hyperkeratotic variant of porokeratosis Mibelli is a distinct entity: clinical and ultrastructural evidence.

An isolated case with the hyperkeratotic variant of porokeratosis Mibelli (PM) is reported. The 62-year-old woman developed multiple brown macules with well demarcated large keratotic nodules on both legs. Histopathological studies revealed the presence of a cornoid lamella characteristic of porokeratosis. Ultrastructural investigations revealed dyskeratotic as well as edematous, swollen keratinocytes; autophagocytotic vacuoles were visible. The clinical and ultrastructural peculiarities of the hyperkeratotic variant of PM suggest the possibility of a separate entity.