D3.374 - Recall urticaria to dalteparin sodium in a patient with previous systemic reaction to nadroparin calcium

Introduction: Recall urticaria (RU) is a rare biological phenomenon characterized by the appearance of urticaria at the sites of previous antigen-allergen injection, as well as increased sensitivity of endothelial cells upon re-exposure to the antigen-allergen but by a different way of introduction into the body. Allergic reactions to low molecular weight heparin (LMWH) mainly occur as late-type hypersensitivity reactions at the sites of drug application.

AIM: Presentation of patient with recall urticaria to dalteparin after a previous systemic reaction to nadroparin.

Case report: A 25-year-old male patient received prophylactic doses of low molecular weight heparin (LMWH) - nadroparin calcium 5700 IJ/0.6 ml during several days, after a fracture of the right lower leg. After 7 days from the beginning of the therapy, a reaction occurred in the form of itching of the skin with the appearance of urticaria on the trunk and extremities. Skin rash resolved after receiving parenteral corticosteroid therapy with antihistamines. After a month in hospital conditions, an in vivo provocation test was performed with low molecular weight heparin - dalteparin sodium 5000IJ/0.2 ml. After 15 minutes of the subcutaneous application of 0.2 ml of dalteparin, in the region of the left upper arm, there was the appearance of severally urticaria of approximately 5 mm diameter periumbilically at the sites of previous administration of nadroparin, as well as one urtica at the site of dalteparin application. The patient also mentioned the feeling of itching of the whole skin, but objectively without the appearance of urticaria in other regions. After the administration of methylprednisolone and chloropyramine, the skin changes subsided.

Conclusion: Pathogenetic mechanisms of RU have not been fully elucidated. This phenomenon can occur several years after the initial exposure to the allergen, so it should be taken into account that long-term immune memory mechanisms are responsible for this type of hypersensitivity reaction. Mast cells, as one of the main mediators of allergic reactions according to type I hypersensitivity, probably play an important role in the emergence of localized "immunological tissue memory". It is likely that there is an increased concentration and reactivity of mast cells at the site of the reaction, as well as an increased sensitivity of endothelial cells. Other possible mechanisms include long-acting plasma cells that produce immunoglobulin E antibodies, memory T effector cells that support increased sensitivity, and local effector cell reactivity to mast cell mediators. It is believed that long-term "type I tissue memory" is primarily responsible for the appearance of RU. RU can be caused by allergen immunotherapy, oncological immunotherapy, intravenous injections, levofloxacin, as well as inhalation of aerosols.