Nonmutilating palmoplantar and periorificial kertoderma: a variant of Olmsted syndrome or a distinct entity?

Background Olmsted syndrome is a rare keratinization disorder characterized by mutilating palmoplantar and periorificial keratoderma as the two major diagnostic features. Some authors believe that atypical cases without this standard combination may not really belong to Olmsted syndrome. Herein, we describe two familial cases with congenital nonmutilating palmoplantar and periorificial keratoderma, and discuss their similarities and differences with Olmsted syndrome. Patients The study included two sisters who presented with focal and punctate nonmutilating palmoplantar keratoderma (PPK), periorificial hyperkeratotic plaques, and widely distributed keratotic lesions. Fragile denuded areas of the skin were found in sites exposed to trauma. Fingernails showed a characteristic form of leukonychia. Results Histopathology of plantar keratoderma showed psoriasiform hyperplasia with marked compact hyperkeratosis, while vicinity of denuded skin revealed thin parakeratotic zone and dissolution of the granular cell layer. Immunohistochemistry demonstrated suprabasal staining pattern for acidic keratin (AE1) and uniform positivity, starting four to six layers above the basal layer, for cytokeratin 10. Electron microscopy showed defective keratinization. Cytogenetic studies revealed normal karyotype and no chromosomal breakage. Conclusion Our cases share Olmsted syndrome in the early onset, and the presence of symmetrical PPK, periorificial keratoderma and keratotic lesions. However, the striking nonmutilating nature of PPK and the presence of unique features in our patients suggest a newly described keratinization disorder.