Unusual reaction to subcutaneous heparin

Delayed-Type Hypersensitivity and Cross-Reactivity to Heparins and Danaparoid: A Prospective Study

“…These results are in line with previous findings published mainly in the allergologic literature. 10,16,18,19 Moreover, they support the concept that subcutaneous testing of a panel of heparins (including UFH with or without preservatives) is necessary to detect preparations which are tolerated by patients with DTH to a specific heparin. 4,[10][11][12]18,19 There is a sharp correlation between latency period for skin lesions during treatment and either first-time or multiple treatments with heparins.…”

“…Histopathology reveals edema and a lymphocytic infiltrate with numerous eosinophils of the papillary dermis, often accompanied by epidermal spongiosis (Figure 2), and is thus sharply distinct from heparin-induced skin necrosis, which is characterized by fibrinous thrombi in dermal venules and absence of inflammation. 3,[15][16][17] Subcutaneous testing is now widely accepted as the most reliable method for identifying DTH reactions to heparins, whereas patch testing yields a high rate of false-negative results. 3,4,11,12,18 In this study we investigated, by skin testing, the in vivo pattern of cross-reactivity between different LMWHs, UFHs, and danaparoid in a series of patients with a diagnosis of suspected type IV allergy to heparin.…”

Delayed hypersensitivity at the injection sites of a low‐molecular‐weight heparin

“…Delayed hypersensitivity at the site of injection of heparin is rare and was first reported in 1952 (1). It was first often mistaken for cutaneous necrosis, but is now well differentiated (2)(3)(4). The skin reaction is due to heparin itself and not to preservatives (5)(6)(7).…”

Delayed-Type Hypersensitivity and Cross-Reactivity to Heparins and Danaparoid: A Prospective Study

“…DTH reactions present with erythematous, infiltrated, or vesicular (eczema‐like) itchy plaques usually confined to the injection sites (Figure 1). Histopathology reveals edema and a lymphocytic infiltrate with numerous eosinophils of the papillary dermis, often accompanied by epidermal spongiosis (Figure 2), and is thus sharply distinct from heparin‐induced skin necrosis, which is characterized by fibrinous thrombi in dermal venules and absence of inflammation 3,15–17 . Subcutaneous testing is now widely accepted as the most reliable method for identifying DTH reactions to heparins, whereas patch testing yields a high rate of false‐negative results 3,4,11,12,18 …”