ABSTRACT
Atopic dermatitis (AD) is an inflammatory skin disease closely related to impairment of skin barrier function.Hereditary factors,life style and exposure to the environment all contribute to the occurrence of AD.Even though AD occurs mostly in infants,sometimes it may initially occur in adults,which is called adult-onset AD (AOAD).There are evident differences in types,immunological mechanisms and association with other diseases between childhood AD and AOAD.The lesional distribution of AOAD is similar to that of childhood AD,while AOAD is characterized by subacute and chronic dermatitis,and mainly manifests as dry hypertrophic lesions rarely complicated with exudation.Th1/Th2 imbalance and hyperfunction of antigen-presenting cells are immunological basis of AD occurrence.Moreover,FLG gene mutations are associated with the occurrence of AD.Acquired expression defect in the FLG gene induced by elevated levels of interleukin-13 (IL-13) only occurs in adults,suggesting that AOAD is different from AD that initially occurs during infancy and continues into adulthood.Infection,changes of bacterial flora in the skin and intestinal tract,and smoking are all important causative factors of AOAD,thus enquiries about histories of related diseases and smoking are helpful for the diagnosis of AOAD.
ABSTRACT
BACKGROUND: Most study concerning the prevalence and dermatological manifestations of the extrinsic and the intrinsic form of atopic dermatitis (AD) were performed in children and adult AD related to the early-onset AD extending to adult life. Adult-onset AD is a subgroup of AD. Apart from the typical eczematous flexural distribution pattern of AD, this group may also have nontypical morphology and localization. OBJECTIVE: The purpose of this study was to compare the clinical and diagnostic features of Thai patients with extrinsic and intrinsic type of adult-onset AD. METHODS: We retrospectively studied case records of patients diagnosed as adult-onset AD at the skin allergy clinic, Department of Dermatology, Siriraj Hospital, Mahidol University, Bangkok, Thailand from June, 2006 to May, 2008. The diagnosis of AD was made according to the criteria of Hanifin and Rajka and the severity of AD in each patient were assessed using the eczema area and severity index and the Rajka and Langeland score. RESULTS: Fifty six patients were enrolled. Eighty-seven percent of patients were extrinsic AD (eAD). Females predominated in both groups. Patients with eAD more commonly had typical lichenified/exudative eczematous lesions, especially on the antecubital and popliteal areas, when compared with patients with intrinsic AD (iAD). Nummular and follicular lesions were more commonly seen in iAD group than the eAD group. The most common area of involvement in the iAD was non-flexural area, followed by flexural area and extensor area. The severity of both iAD and eAD did not show a significant difference. CONCLUSION: The eAD type of adult-onset AD was more common than the iAD type. Patients with eAD frequently had flexural lichenification whereas the iAD group tended to have nonflexural area involvement. The severity of both iAD and eAD did not show a significant difference.