Introduction: Heparin-induced bullous hemorrhagic dermatosis (HBHD) is an unusual cutaneous adverse reaction to heparin characterized by acute onset of hemorrhagic bullae.Methodology: An exuberant case of HBHD is reported, and a revision of previously reported cases indexed on PubMed is provided. Cases were tabulated to the following parameters: sex, age, type of heparin and route of administration, associated medical procedure, number of days between heparin start and onset of lesions, site of the lesions, level of blister on histopathology, inflammatory infiltrate on histopathology, direct immunofluorescence findings, heparin-related intervention, number of days to resolution of skin lesions, associated hemorrhagic event, and outcome.Case report: A 21-year-old woman with end-stage renal disease was receiving intravenous unfractioned heparin (UFH) during hemodialysis section for the past 3 months. Four hours after using for the first time an arteriovenous fistula punctured on her right wrist, the patient noticed the onset of vesicles and blisters on the right forearm containing citrus or serohemorrhagic exudate, which became overt hemorrhagic in 24 hours. Histopathology depicted a nonacantholytic subcorneal blister containing erythrocytes and plasma without any significant dermal inflammatory infiltrate.Results: Sixty cases of HBHD were included. HBHD affected predominantly men, with a male/female rate of 2.75. The age range was from 21 to 94 years, with an average of 70.8 and a median of 72 years. Nine patients used UFH, and 54 patients used low molecular weight heparins (3 patients used both). The lapse of time between the start of heparin and the onset of skin lesion varied from 6 hours to 240 days, with an average of 17.3 days and a median of 7 days. Limbs were affected in most of the cases. The level of the blister was subcorneal in 10 patients, intraepidermal in 30, subepidermal in 8, and both intraepidermal and subepidermal in 1. In 33 cases, there was no significant dermal inflammatory infiltrate. Pure lymphocytic inflammatory infiltrate was present in 10 cases. Eosinophils were found within the dermal inflammatory infiltrate in 2 cases, neutro-phils in 2, and a mixture of eosinophils and neutrophils in other 2. Direct immunofluorescence was performed in 18 cases, all of them with negative results.Discussion: We hypothesize that mechanical trauma, skin fragility, and the anticoagulation effect of heparin might contribute concomitantly to the development of the lesions and speculate that subepidermal blisters in HBHD could be formed by rupture of the floor of a former intraepidermal blister.
