Introduction
Demographics
Causes
Clinical features
Complications
Diagnosis
Differential diagnosis
Treatment
Prevention
Outcome
Heparin-induced haemorrhagic bullous dermatosis (HBD) is a rare, self-limited adverse cutaneous reaction to heparin.
Also known as bullous haemorrhagic dermatosis, this reaction is characterised by the appearance of tense haemorrhagic bullae distant to the heparin injection site. Bullae can appear days to weeks after injection, most often after one week.
Heparin can also give rise to other cutaneous reactions, including:
Heparin-induced haemorrhagic bullous dermatosis is rare and likely underreported. It can affect anyone following administration of unfractionated heparin (UFH) or low molecular weight heparins (LMWHs), even at prophylactic doses. Based on limited case reports, HBD is more common in males than females and tends to affect older adults (mean age 72 years).
Enoxaparin is the most frequently implicated drug, though it is also the most commonly used LMWH. Cross-reactions between LMWHs and fondaparinux (synthetic factor Xa inhibitor) have also been reported.
The exact mechanism responsible for heparin-induced haemorrhagic bullous dermatosis is unknown. Fragility of the epidermal-dermal junction combined with trauma and the anticoagulation effects of heparin are thought to contribute to its development.
Furthermore, the distribution of lesions away from the injection site suggests a systemic response rather than local heparin toxicity.
Heparin-induced haemorrhagic bullous dermatosis is characterised by the sudden appearance of multiple, irregularly scattered, tense haemorrhagic bullae typically 7 days post-administration.
There are no documented variations across skin type and no known associations with race.
The main complication of heparin-induced haemorrhagic bullous dermatosis is cutaneous bleeding. There have been rare reports of intracranial haemorrhage associated with HBD, though a causal relationship has not been established.
Diagnosis of heparin-induced haemorrhagic bullous dermatosis is made clinically due to its typical appearance and temporal association with heparin administration. If there is uncertainty surrounding the diagnosis, a skin biopsy may be performed.
The histopathology of HBD is non-specific and reveals:
Platelet counts and coagulation studies are often within normal limits.
Treatment is usually not required for heparin-induced haemorrhagic bullous dermatosis as the lesions are benign and resolve spontaneously. Anticoagulation may be changed or stopped if there are concerns regarding bleeding.
There are no proven effective methods to prevent heparin-induced haemorrhagic bullous dermatosis, aside from not administering heparin.
Heparin-induced haemorrhagic bullous dermatosis usually resolves spontaneously within two weeks regardless of whether anticoagulation is continued or stopped. Recurrence can occur on re-exposure.
