The risk for cross-reactions after a cutaneous delayed-type hypersensitivity reaction to heparin preparations is independent of their molecular weight: a systematic review

Cutaneous hypersensitivity reaction to low molecular weight heparins in pregnancy, cross reactivity and prednisolone treatment: A case report

In pregnant women, low molecular weight heparin is recommended as the preferred agent for venous thromboembolism prophylaxis and treatment. Despite their widespread application, heparin-induced skin lesions are probably under-reported and under-estimated. We present a case report of a primigravida treated with low molecular weight heparin for deep vein thrombosis, who developed a delayed-type hypersensitivity reaction to enoxaparin, tinzaparin and dalteparin. As the patient was pregnant, treatment options were restricted. Tolerance was achieved with dalteparin with adjuvant administration of prednisolone. An attempt to decrease prednisolone dose triggered delayed-type hypersensitivity reaction recurrence that was solved by keeping the initial prednisolone prescription. To the best of our knowledge, there are no described cases using this approach. In cases of delayed-type hypersensitivity reaction to low molecular weight heparin during pregnancy our case suggests that switching low molecular weight heparin and adjuvant administration of prednisolone can be an option.

Hypersensitivity reactions to low molecular weight heparins: different patterns of cross-reactivity in 3 patients

Low molecular weight heparins (LMWHs) are used for a variety of indications. The most common type of hypersensitivity reactions to LMWHs are delayed-type hypersensitivity reactions (DHR). Immediate-type hypersensitivity reactions (IHR) occur only sporadically. Cross-reactivity of different LMWHs is a common and unpredictable problem. We present 2 cases of patients who developed DHR to nadroparin and enoxaparin, respectively. The third case presents a patient who developed IHR to nadroparin. Skin tests confirmed the hypersensitivity in all cases. In the cases of DHR, a skin test negative LMWH was identified and was tolerated in a challenge test. In the IHR case, cross-reactivity to all tested LMWHs was established. We hypothesize that the degree of cross-reactivity might depend on the type of hypersensitivity reaction with immediate reactions linked to more extensive cross-reactivity than delayed reactions. This is important to consider because, at least in some cases, a safe alternative LMWH can be identified.