Coma Blisters: A Case Report and Review of the Literature

Abstract

Coma blister is an uncommon cutaneous manifestation classically described following conditions causing impaired consciousness, most frequently associated with drugs like overdoses of central nervous system depressants. However, they have also been described in association with other non-drug related cases of impaired consciousness and even in the setting of non-comatose conditions. They clinically present as tense blisters or bullae, occasionally resembling erosions and violaceous plaques, few in number over normal or edematous skin. They can occur on both dependent and non-dependent areas of the trunk and extremities. Coma blisters typically appear within 24 hours after the onset of unconsciousness and resolves spontaneously within 10-14 days. The exact pathophysiology behind coma blisters remains controversial as it cannot be fully explained by pressure effects nor by toxic effects of any specific medication and no relation to any underlying infection or autoimmune condition have been found so far. The hallmark and the most frequent histopathological feature of the lesion consists of necrosis of the eccrine gland. There is no specific treatment available for coma blisters. We herein present a 49- year-old Thai male who developed bullae on his extremity after prolonged impairment of consciousness without any predisposing associated substance that could cause the bullae. We also reviewed the literature on coma blisters in adult as well as in pediatric patients in terms of clinical characteristics and histopathological findings.