Summary
Localized hypersensitivity reactions to subcutaneous heparin injections have been
described since 1952. Yet, the incidence of these reactions, which are distinct from
skin lesions associated with heparin-induced thrombocytopenia type II (HIT II), remains
uncertain. However, in the last 10 years an increasing number of patients have been
reported, leading to the assumption that cutaneous hypersensitivity reactions towards
heparin are underreported. Clinically patients present with itching, sometimes infiltrated,
and blistering erythemas at the injection sites of heparins. The diagnosis of cutaneous
heparin allergy may, on the one hand, lead to delay of required medical or surgical
treatment. On the other hand, delayed initiation of treatment may lead to a generalized
eczematous reaction. Hence, from review of 223 cases of patients with cutaneous hypersensitivity
reactions to heparin, we here summarize the clinical picture of cutaneous type IV
allergic reactions, define risk factors on both the patient- and drug-side, and give
an overview of principle therapeutic alternatives, as well as recommendations for
treatment options for emergency and elective patients. As the proposed management
of patients with cutaneous hypersensitivity reactions to heparin may have fatal consequences
when applied in patients with HIT type II, diagnosis of skin lesions in heparin-treated
patients needs to be precise.
Keywords
Heparin - inflammation - pharmacology - allergy