Eschar Formation Following Coma Bullae: A Case Report

Coma blisters, or coma bullae, are lesions often seen in the setting of impaired consciousness. Most commonly associated with drug-induced comas, coma bullae have been repeatedly linked to central nervous system (CNS) depressing agents, such as opiates. These lesions are believed to develop due to a complex multifactorial process involving external pressure on the skin, which leads to hypoxia and eventual death of eccrine sweat glands. In addition, the vasoactive and inflammatory properties of CNS depressing agents may play a role in this process. Come bullae usually develop on pressure points 48-72 hours after the onset of impaired consciousness and are self-limiting. We present the case of a 68-year-old male who was brought to the emergency department after being found unresponsive on the street. The urine drug screen was positive for cocaine and fentanyl. The initial examination showed several large, non-tender bullae on his scalp that continued to expand over two days. He subsequently developed similar lesions on his thighs, right shoulder, and knuckles. Dermatology was consulted and clinically diagnosed the patient with coma bullae, likely attributed to his altered consciousness and opiate use. Notably, more violaceous bullae were found on the bilateral lower extremities, with dermatology suspecting additional vasculitic features related to concurrent opiate and cocaine use. Skin biopsy and aspiration were deferred to avoid the risk of infection, and the patient was discharged per dermatology's recommendations for no immediate intervention. He continued to follow with wound care for the next six months, with most of the bullae healing. However, eschars developed over the scalp and left lower extremity, requiring debridement by general surgery. This case report underscores a unique manifestation of coma bullae. Unlike typical presentations localized to pressure-dependent areas and appearing after two to three days of unconsciousness, our patient exhibited blisters in atypical sites with associated vasculitic features. Moreover, the development of eschars over time may be linked to ongoing vasoactive drug use, reperfusion injury, and social determinants of health. This case highlights the complex and multifactorial nature of coma bullae, emphasizing the challenges in wound care and management despite their expected self-resolution.