Clinical Manifestation and Classification of Japanese patients with Inherited Keratinizing Disorders

Objective: Inherited keratinizing disorders are a spectrum of relatively rare skin diseases with a variety of congenital defects in the keratinizing process. In this study, we evaluated patients with inherited keratinizing disorders in the Tokyo urban area from the clinicians' viewpoint. Patients: We retrospectively evaluated 77 cases of inherited keratinizing disorders (male/female: 43/34 cases, mean age at first visit: 20.2 years) who visited our institution in the past 5 years. Methods: The cases were classified into 3 major groups; ichthyoses, palmoplantar keratodermas (PPK), and macular- and punctuate-type keratodermas. Definite diagnoses were achieved according to the clinico-pathological features and genetic analyses. Results: The ichthyoses group (48 cases: 62.3%) consisted of dominant ichthyosis vulgaris (IV: 13 cases), X-linked ichthyosis (XLI: 16 cases), lamellar ichthyosis (LI: 4 cases), and bullous/nonbullous congenital ichthyosiform erythroderma (BCIE and NBCIE: 3 cases each). PPK groups (21 cases: 27.3%) included Vörner-type (7 cases) and Nagashima-type (9 cases). Macular/punctuate-type keratodermas (8 cases: 10.4%) included 4 cases of Darier's disease. The discrepancy between percentages above and reported incidence of each disorder most likely resulted from the increasing tendency of visits in patients with severe symptoms. The therapeutic approach was application of topical moisturizers, in combination with topical vitamin D3 analogue, steroid, and antibiotics/antifungal agents. In addition, some cases were treated with oral retinoids and antihistamines. Conclusions: Although genetic analysis is necessary for definitive diagnosis, this simplified classification based on clinical features and morphological changes seems to be useful for clinical diagnosis and first-line aid for patients. The establishment of guidelines for diagnosis, therapy and patient care of inherited keratinizing disorders in Japan is urgently needed.