Eczematous infiltrated plaques to subcutaneous heparin: a type IV allergic reaction

Fatal Course of Cutaneous Cholesterol Embolization Syndrome: A Case Report

Cholesterol embolization syndrome is an increasing but underestimated problem after endovascular intervention or after the start of thrombolytic therapies. Embolies from the aortic wall involves abdominal organs and the skin of the lower extremities or buttocks. In our case a progressive ulceration and necroses occurs spontaneously. Endovascular treatment of the lower extremities was successful for a short period. Due to the progression of necrosis, both legs were amputated. Biopsies were taken from the skin were initially no directions to the diagnosis of Cholesterol embolization syndrome. After a second elliptical excision biopsy the diagnosis of cholesterol embolization syndrome was confirmed. Because the rapid progression of skin necroses despite the treatment of prednisone, patient died due to sepsis and renal failure. This case shows when arterial revascularization is performed and progression in skin necrosis occurs despite optimal arterial vascular status the diagnosis CES should be considered and treated in an early state of disease.

Delayed-Type Heparin Allergy: Intravenous Tolerance Despite Inflammatory Skin Reaction After Subcutaneous Injection

BACKGROUND

Heparin allergy most frequently manifests as delayed-type hypersensitivity (DTH) causing an itchy inflammatory skin reaction at the site of subcutaneous injection. An important differential diagnosis is circumscribed skin necrosis due to heparin-induced thrombocytopenia.

OBJECTIVES

An inflammatory skin reaction to subcutaneously injected heparin generally entails the quest for alternative anticoagulation; concerns may particularly arise in an emergency situation requiring intravenous heparin administration.

METHODS

All heparin DTH cases seen in our department over the last 17 years underwent standardized allergy diagnostics including challenge testing, that is, subcutaneous injection of fondaparinux and intravenous administration of unfractionated heparin (UFH).

RESULTS

Of a total of 50 patients with confirmed heparin allergy, DTH was found in 48 (96.0%), and immediate-type, presumably IgE-mediated hypersensitivity was diagnosed in only 2 (4.0%). In the 48 DTH cases, intradermal testing revealed broad cross-reactivity between UFH and low-molecular-weight heparins (LMWH) including nadroparin, dalteparin, and enoxaparin. Cross-reactivity with (or concomitant sensitization to) fondaparinux was seen in only 3 (6.3%) cases. Intravenous administration of UFH was tolerated by all 45 patients challenged, despite DTH to UFH and LMWH as demonstrated by intradermal testing.

CONCLUSIONS

If an inflammatory skin reaction at the site of subcutaneously injected heparin is observed or reported without any evidence of skin necrosis or thrombocytopenia, intravenous administration of UFH seems to be sufficiently safe and may be considered without allergy testing if urgently indicated in an emergency situation. Fondaparinux is the most suitable alternative for subcutaneous application.

The Role of Patch Testing in Evaluating Delayed Hypersensitivity Reactions to Medications

Confirming drug imputability is an important step in the management of cutaneous adverse drug reactions (CADR). Re-challenge is inconvenient and in many cases life threatening. We review the literature on ideal patch testing technique for specific CADRs. Testing should be performed approximately 3 months after the resolution of the eruption using standard patch testing techniques. Commercially available patch test preparations are available for a minority of drugs, so in most cases, testing should be performed with the drug at various recommended concentrations and in different vehicles. Testing to all known excipients, such as dyes, vehicles and preservatives is also important. Immunosuppressive medications should be discontinued or down titrated to the lowest tolerable dose to decrease the risk of false negative reactions. We provide an overview of expert recommendations and extant evidence on the utility of patch testing for identifying the culprit drug in common CADRs and for specific drug or drug classes. Overall, there appears to be significant variability in the patch test positivity of different drugs, which is likely the result of factors intrinsic to the drug such as dermal absorption (as a function of lipophilicity and molecular size) and whether the drug itself or a downstream metabolite is implicated in the immune reaction. Drugs with high patch test positivity rates include beta-lactam antibiotics, aromatic anticonvulsants, phenytoin, and corticosteroids, among others. Patch testing positivity varies both as a function of the drug and type of CADR. The sum of the evidence suggests that patch testing in the setting of morbilliform eruptions, fixed drug eruption, acute generalized exanthematous pustulosis, and possibly also drug-induced hypersensitivity syndrome, photoallergic and eczematous reactions may be worthwhile, although utility of testing may vary on the specific drug in question for the eruption. It appears to be of limited utility and is not recommended in the setting of other complex CADR, such as SJS/TEN and leukocytoclastic vasculitis.

Matrix therapy is a cost-effective solution to reduce amputation risk and improve quality of life: pilot and case studies

Introduction: Chronic, non-healing ulcers remain one of the most challenging clinical situations for health care practitioners. Often, conventional treatments fail and lead to amputation, further decreasing the patient's quality of life and resulting in enormous medical expenditures for healthcare systems. Here we evaluated the use of and cost-effectiveness of the RGTA (ReGeneraTing Agents) medical device CACIPLIQ20 (OTR4120) for chronic lower-extremity ulcers in patients with Leriche and Fontaine Stage IV peripheral arterial disease who were not eligible for revascularization. Methods: This uncontrolled pilot study included 14 chronic lower extremity ulcers in 12 patients in one hospital. The pilot study included 12 patients with TcPO₂ < 20 mm Hg and ABPI < 0.5 who had either a minimum of one chronic lower extremity ulcer or a chronic ulcer related to amputation. OTR4120 was applied twice a week or until complete healing, for up to 12 weeks. Ulcer surface area reduction (%)after 2, 4, 8 and 12 weeks, appearance after 4 weeks, and healing after 12 weeks were measured and recorded. Results: A 35% reduction in ulcer size was achieved after 4 weeks. 7 (50%) out of 14 ulcers completely healed within 1 to 3 months of treatment. Discussion: OTR4120 is an effective therapeutic option for patients with chronic lower extremity ulcers, can provide major improvement of quality of life and has the added benefit of being a significant cost-effective solution for healthcare systems.

Pharmacology of Heparin and Related Drugs

Heparin has been recognized as a valuable anticoagulant and antithrombotic for several decades and is still widely used in clinical practice for a variety of indications. The anticoagulant activity of heparin is mainly attributable to the action of a specific pentasaccharide sequence that acts in concert with antithrombin, a plasma coagulation factor inhibitor. This observation has led to the development of synthetic heparin mimetics for clinical use. However, it is increasingly recognized that heparin has many other pharmacological properties, including but not limited to antiviral, anti-inflammatory, and antimetastatic actions. Many of these activities are independent of its anticoagulant activity, although the mechanisms of these other activities are currently less well defined. Nonetheless, heparin is being exploited for clinical uses beyond anticoagulation and developed for a wide range of clinical disorders. This article provides a "state of the art" review of our current understanding of the pharmacology of heparin and related drugs and an overview of the status of development of such drugs.

The complex clinical picture of side effects to anticoagulation

Inflammatory plaques at injection sites are frequent side effects of heparin treatment and a clinical symptom of delayed-type hypersensitivity (DTH) to heparin. In most cases, changing the subcutaneous therapy from unfractionated to low-molecular-weight heparin or treatment with heparinoids does not provide improvement because of extensive cross-reactivity. Because of their completely different chemical structure, hirudins are a safe alternative for anticoagulation. Despite DTH to subcutaneously injected heparins, patients tolerate heparin intravenously. Therefore, in case of therapeutic necessity and DTH to heparins, the simple shift from subcutaneous to intravenous heparin administration is justified. Skin necrosis is a rare complication of anticoagulation. Heparin-induced skin necrosis is 1 of the symptoms of immune-mediated heparin-induced thrombocytopenia and should result in the immediate cessation of heparin therapy to prevent potentially fatal thrombotic events. This is in contrast to coumarin-induced skin necrosis, where therapy may be continued or restarted at a lower dose.

Incidence and causes of heparin-induced skin lesions

BACKGROUND

Little is known about the incidence and causes of heparin-induced skin lesions. The 2 most commonly reported causes of heparin-induced skin lesions are immune-mediated heparin-induced thrombocytopenia and delayed-type hypersensitivity reactions.

METHODS

We prospectively examined consecutive patients who received subcutaneous heparin (most often enoxaparin or nadroparin) for the presence of heparin-induced skin lesions. If such lesions were identified, we performed a skin biopsy, platelet count measurements, and antiplatelet-factor 4 antibody and allergy testing.

RESULTS

We enrolled 320 patients. In total, 24 patients (7.5%, 95% confidence interval [CI] 4.7%-10.6%) had heparin-induced skin lesions. Delayed-type hypersensitivity reactions were identified as the cause in all 24 patients. One patient with histopathologic evidence of delayed-type hypersensitivity tested positive for antiplatelet-factor 4 antibodies. We identified the following risk factors for heparin-induced skin lesions: a body mass index greater than 25 (odds ratio [OR] 4.6, 95% CI 1.7-15.3), duration of heparin therapy longer than 9 days (OR 5.9, 95% CI 1.9-26.3) and female sex (OR 3.0, 95% CI 1.1-8.8).

INTERPRETATION

Heparin-induced skin lesions are relatively common, have identifiable risk factors and are commonly caused by a delayed-type hypersensitivity reaction (type IV allergic response).

Acute generalized exanthematous pustulosis from dalteparin

Heparins are widely used for the prophylaxis and treatment of venous thromboembolism. Several types of immunologically mediated reactions to heparins are reported, among them delayed-type hypersensitivity reactions with erythematous, infiltrated itchy plaques at injection sites. We describe a female patient, whose localized reaction from dalteparin was followed by a generalized rash presenting as acute generalized exanthematous pustulosis. Subcutaneous provocation testing showed cross-reactions to enoxaparin, certoparin, reviparin, nadroparin, danaparoid, fondaparinux, but not to pentosan polysulfate. The danaparoid and in a lesser extent the nadroparin patch showed pustules. Within the next day, a generalized rash developed. The upper aspect of her trunk was highly affected and showed discrete pustules. Despite the fact that low molecular-weight heparins are widely prescribed, this is, to our knowledge, the first observation of a pustular drug eruption attributable to this class of substances.

Allergy to heparins and anticoagulants with a similar pharmacological profile: an update

Heparins are widely used as anticoagulants. Immunologically-mediated side effects raise the question as to whether other substances with heparin-like pharmacological effects can be safely applied. Hypersensitivity reactions to heparin consist of heparin-induced immune thrombocytopenia, allergic vasculitis, hypereosinophilia, immediate hypersensitivity as well as delayed-type skin reactions. Hypersensitivity to unfractionated and low-molecular-weight heparins and semisynthetic heparinoids is increasingly common, and the pathogenesis, however, is still not fully understood. Clinically, this phenomenon is of relevance because of its increasing incidence and the resulting therapeutic difficulties that arise because several cross-reactions between unfractionated and low-molecular-weight heparins as well as between various heparins and heparinoids have been observed. In some patients with cross-reactivity between various heparins and semisynthetic heparinoids, recombinant hirudins, may be safe and effective. Combined allergy to recombinant hirudins and heparins, however, has been reported. Therefore, there is an urgent need for therapeutic alternatives.

Hypersensitivity reactions to anticoagulant drugs: diagnosis and management options

Anticoagulants, including heparins, coumarins, hirudins, and some of the previously used plasma volume expanders, belong to the most widely used drugs. Hypersensitivity reactions from these agents are uncommon. However, they may have a considerable impact on patient safety and treatment decisions. Therefore, early diagnosis of potentially life-threatening adverse events and identification of alternatives is clinically important. This review contains an update on current knowledge about hypersensitivity reactions caused by the different anticoagulants. In addition, it discusses pathophysiologic mechanisms, diagnostic possibilities, and management options. The most common hypersensitivity reactions are erythematous plaques, occurring with a delay after subcutaneous application of heparins. Seldom they turn into maculopapular exanthema. Other hypersensitivity reactions are rare but may be life-threatening, e.g. skin necrosis because of heparin-induced thrombocytopenia. Skin and provocation tests with immediate and late readings are the most reliable diagnostic tools for heparin- or hirudin-induced urticaria/anaphylaxis or heparin-induced delayed plaques. If necrosis from heparins or coumarins is suspected, skin tests are contraindicated. In anaphylactic reactions caused by dextrans or hydroxyethyl starch skin tests are useless. Most in vitro tests have a low sensitivity and are not generally available. Therefore, in some anticoagulant-associated hypersensitivity reactions detailed allergologic investigation may help to identify safe treatment alternatives. However, several tests may be needed, and the procedures are usually time-consuming.

Eczema-like plaques secondary to enoxaparin

Low-molecular-weight heparins are used extensively in acute medicine. They are generally well tolerated but may cause a rare, eczema-like type IV hypersensitivity reaction. We report 3 cases of this eruption and speculate that it may be significantly under-reported due to misidentifying the causal drug, which may have serious consequences. We discuss treatment alternatives such as fondaparinux sodium, which may rarely cross-react.

Calcifying panniculitis following subcutaneous injections of nadroparin-calcium in a patient with osteomalacia

Calcifying panniculitis is a rare form of calcinosis cutis belonging to the spectrum of calciphylaxis that has almost invariably been described in patients with severe renal disturbances. We report a patient with osteomalacia without chronic renal failure, who developed calcifying panniculitis following subcutaneous administration of nadroparin-calcium. Light microscopy studies of biopsy specimens revealed multiple foci of microcalcification within the adipose lobules, in the interadipocyte spaces, in connective tissue septa and in the media of small arteries in the subcutis. The patient had an elevated level of intact parathyroid hormone, whereas the calcium-phosphorus product was normal. The lesions slowly resolved upon discontinuation of nadroparin. We conclude that calcifying panniculitis is a rare complication associated with the subcutaneous administration of nadroparin-calcium that may rarely also occur in the absence of renal disturbances. Low molecular weight calcium-containing heparins should probably be used with caution in the presence of hyperparathyroidism.

Drug patch testing in systemic cutaneous drug allergy

Patch testing with the suspected compound has been reported to be helpful in determining the cause of a cutaneous adverse drug reaction (CADR) and in studying the pathophysiological mechanisms involved. The main advantages of drug patch tests are that they can be done with no hospital surveillance because they induce only rarely adverse reactions and that any commercialized form of a drug can be used. In contrast, intradermal tests can be performed only with injectable forms or with a pure and sterile form of the drug. It is advised to perform drug patch tests during the 6 months following the CADR as we do not know whether positive results will persist. Due to the possibility that a low concentration might yield false negative results, drug patch tests have to be performed with rather high concentrations of the commercialized form of the drug, mostly diluted at 30% in petrolatum and/or in water. For some drugs and severe CADR, it is necessary to tests with lower concentrations or in other vehicles. Drug patch tests are positive in ca. 32-50% of patients who have developed a CADR. The clinical relevance of drug patch tests depends on the clinical features of the CADR (valuable in testing generalized eczema, systemic contact dermatitis, maculopapular rash, acute generalized exanthematous pustulosis, fixed drug eruption) and on the involved drug. As false positive results can be observed, it is always necessary to consider the relevance of any positive drug patch test. Their specificity and their negative predictive value have not been yet determined.

Delayed-type hypersensitivity skin reactions due to heparins and heparinoids. Tolerance of recombinant hirudins and of the new synthetic anticoagulant fondaparinux

Eczema-like, infiltrated plaques at subcutaneous heparin-injection sites are well-documented side effects of these anticoagulants. They are due to delayed-type hypersensitivity. In 4 patients, patch, intradermal and subcutaneous tests were performed with a panel of unfractionated heparins (UFHs), low-molecular-weight heparins (LMWHs), heparinoids, recombinant hirudins and a new synthetic pentasaccharide anticoagulant fondaparinux sodium, to find safe alternatives. 3 patients were sensitized to all the UFHs and LMWHs. The LMWH tinzaparin sodium and the heparinoid pentosan polysulfate were found to be a possible substitute in patient no. 1 and 2, respectively. The recombinant hirudins and fondaparinux sodium were tolerated without any side effects in all patients tested. Fondaparinux is a synthetic copy of a pentasaccharide sequence in the heparin molecule. It is the first in a new class of antithrombotic agents. Our study suggests that it is a new safe alternative in patients with eczema-like, infiltrated plaques at subcutaneous heparin-injection sites.

Eczematous plaques related to unfractionated and low-molecular-weight heparin in pregnancy

The use of low-molecular-weight heparin has been expanded to prevent pregnancy complications such as pregnancy loss, intra-uterine growth restriction and severe early-onset pre-eclampsia in high-risk patients with evidence of acquired or congenital thrombophilia. Therefore, the number of patients with side effects from low-molecular-weight heparin is expected to increase. We describe two women with infiltrating patchy plaques that developed in reaction to low-molecular-weight heparin during pregnancy. In the first patient, a switch to other formulations of heparin and heparinoid failed; the second patient, however, did well when enoxaparin was replaced with dalteparin. This report confirms the risk of skin reactions to enoxaparin and dalteparin, and reports on a skin reaction associated with danaparoid sodium in a pregnant woman.

Progress in the understanding of the pathology and pathogenesis of cutaneous drug eruptions : implications for management

Cutaneous drug eruptions are among the most common adverse reactions to drug therapy. The etiology may reflect immunologic or nonimmunologic mechanisms, the former encompassing all of the classic Gell and Combs immune mechanisms. Cumulative and synergistic effects of drugs include those interactions of pharmacokinetic and pharmacodynamic factors reflecting the alteration by one drug of the effective serum concentration of another and the functions of drugs and their metabolites that interact to evoke cutaneous and systemic adverse reactions. Recent observations include the role of concurrent infection with lymphotropic viruses and drug effects that, through the enhancement of lymphoid blast transformation and/or lymphocyte survival and the contribution of intercurrent systemic connective tissue disease syndromes, promote enhanced lymphocyte longevity and the acquisition of progressively broadening autoantibody specificities. The latter are particularly opposite to drug-induced lupus erythematosus and to drug reactions in the setting of HIV infection. Specific common types of cutaneous drug eruptions will be discussed in this review. Successful management of cutaneous drug eruptions relies upon the prompt discontinuation of the causative medication; most drug eruptions have a good prognosis after this is accomplished. Oral or topical corticosteroids can be administered to aid in the resolution of some types of eruptions. Antihistamines or anti-inflammatory agents may also be administered for some eruptions.

Guidelines for performing skin tests with drugs in the investigation of cutaneous adverse drug reactions

Skin testing with a suspected drug has been reported to be helpful in determining the cause of cutaneous adverse drug reactions (CADR). Many isolated reports of positive drug skin tests are published, but without detailed information concerning the clinical features of the CADR and the method used in performing drug skin tests, such data are not very informative. A working party of the European Society of Contact Dermatitis (ESCD) for the study of skin testing in investigating cutaneous adverse drug reactions, has proposed the herein-reported guidelines for performing skin testing in CADR in order to standardize these procedures. In each reported case, the imputability of each drug taken at the onset of the CADR and a highly detailed description and characterization of the dermatitis need to be given. Drug skin tests are performed 6 weeks to 6 months after complete healing of the CADR. Drug patch tests are performed according to the methods used in patch testing in studying contact dermatitis. The commercialized form of the drug used by the patient is tested diluted at 30% pet. (pet.) and/or water (aq.). The pure drug is tested diluted at 10% in pet. or aq. In severe CADR, drug patch tests are performed at lower concentrations. It is also of value to test on the most affected site of the initial CADR. Drug prick tests are performed on the volar forearm skin with the commercialized form of the drug, but with sequential dilutions in cases of urticaria. Intradermal tests (IDT) are performed with sterile sequential dilutions (10-4, 10-3, 10-2, 10-1) of a pure sterile or an injectable form of the suspected drug with a small volume of 0.04 ml. Drug skin tests need to be read at 20 min and also later at D2 and D4 for patch tests, at D1 for prick tests and IDT. All these tests also need to be read at 1 week. The success of skin tests varies with the drug tested, with a high % of positive results, for example, with betalactam antibiotics, pristinamycin, carbamazepine and tetrazepam on patch testing, or with betalactam antibiotics and heparins on delayed readings of IDT. The results of drug skin tests also depend on the clinical features of the CADR. The use of appropriate control patients is necessary to avoid false-positive results.

[Treatment with danaparoid during pregnancy for a woman with a cutenous allergy to low-molecular-weight heparin]

The authors describe a case of heparin-induced skin reaction due to two preparations of low molecular weight heparin in a pregnant woman. The main characteristics of heparin-related cutaneous allergy are reported. The use of an heparinoid, usually indicated for patients with heparin-induced thrombocytopenia, appeared to be efficient and safe for the mother and her fetus. An epidural analgesia was performed for labor analgesia, 24 hours after the last injection of danaparid of sodium.

Delayed-type hypersensitivity skin reactions caused by subcutaneous unfractionated and low-molecular-weight heparins: tolerance of a new recombinant hirudin

BACKGROUND

Eczema-like infiltrated plaques at subcutaneous heparin injection sites are well-documented side effects of these anticoagulants. However, surgical interventions may be problematic if heparin is urgently needed in these patients.

OBJECTIVE

The aims of this study were to perform extensive allergy skin testing in 24 patients, including a pregnant woman in whom subcutaneous infiltrated plaques developed after subcutaneous heparin injections, and to find safe therapeutic alternatives for this group of patients.

METHODS

Patch, intradermal, and subcutaneous tests were performed with a panel of unfractionated heparins (UFHs), low-molecular-weight heparins (LMWHs), and heparinoids. Since 1997, we have also been performing allergy studies in 8 patients with lepirudin, a new recombinant heparinoid; tolerance of lepirudin was investigated by means of subcutaneous and intravenous injections. The allergy investigations in the pregnant woman were limited to patch tests with heparins and intradermal and subcutaneous tests with pentosanpolysulfate, which are not contraindicated during pregnancy.

RESULTS

In our study population 19 of 23 patients were sensitized to all the UFHs and LMWHs tested when intracutaneous and subcutaneous test results were read at up to 96 hours. LMWH was found to be a possible substitute in 4 patients. Five patients were also sensitized to the heparinoid pentosanpolysulfate. Sensitization to the heparinoid danaparoid was observed in 12 of the 13 patients who were tested with this substance. The administration of an intravenous bolus containing a therapeutic dose of lepirudin after negative subcutaneous provocation was tolerated without any side effects in all 8 patients. The pregnant woman was sensitized to LMWH but tolerated subcutaneous pentosanpolysulfate without any side effects.

CONCLUSION

Extensive allergy skin testing should be performed to find safe alternatives. With few exceptions, all patients react to both UFHs and LMWHs, as well as to danaparoid. The subcutaneous provocation test is the most reliable diagnostic measure. Intravenous lepirudin, and in some cases subcutaneous pentosanpolysulfate, appears to be a safe alternative in patients with eczema-like infiltrated plaques at subcutaneous heparin-injection sites.

Delayed-type hypersensitivity to subcutaneous enoxaparin

BACKGROUND

Enoxaparin and other low-molecular-weight heparins are widely used to prevent and treat thromboembolic disorders. Cutaneous reactions secondary to enoxaparin injections include delayed hypersensitivity skin reactions described as erythematous, infiltrated plaques at injection sites. We studied three cases of erythematous infiltrated plaques after enoxaparin injection in order to establish the allergenic importance of this low-molecular-weight heparin.

METHODS

Patch tests were performed with sodium heparin, calcium heparin, calcium enoxaparin, and calcium nadroparin. A subcutaneous test with calcium heparin and an intravenous challenge test with sodium heparin were done. A punch biopsy was obtained from an erythematous plaque in one patient.

RESULTS

Patch tests were negative to calcium heparin in all patients, positive to enoxaparin and nadroparin in two patients, and positive to sodium heparin in one patient. In two patients, the subcutaneous challenge test was positive, the intravenous challenge test was negative, and the histopathologic appearance of the biopsy resembled a delayed-type hypersensitivity reaction.

CONCLUSIONS

These cases provide evidence of type IV hypersensitivity and the possibility of crossed-allergenicity among unfractionated heparin and low-molecular-weight heparins. We show that the subcutaneous challenge test is the most reliable diagnostic measure.

The use of skin testing in the investigation of cutaneous adverse drug reactions

Skin testing with the suspected compound has been reported to be helpful in determining the cause of cutaneous adverse drug reactions (ADRs), but the value and specificity of these tests need to be determined. In this study, 72 patients with presumed drug eruptions (27 maculopapular, 18 urticarial, seven erythrodermic, nine eczematous, four photosensitivity, three fixed drug eruptions, three with pruritus and one with acute generalized exanthematous pustulosis) were assessed. All had drug patch tests; 46 also had prick tests and 30 had intradermal tests (performed on hospitalized patients using a sterile solution of the suspected drug, diluted sequentially) with immediate and delayed readings. Among these patients, 52 (72%) had a positive skin test reaction, 43%, 24% and 67% in patch, prick and intradermal skin tests, respectively. The results of skin tests varied with the drug tested and with the clinical type of cutaneous ADR, as a significantly higher number of positive patch tests was observed in maculopapular rashes than in urticarial reactions (P = 0.001). This study supports the value of careful sequential drug skin testing in establishing the cause of cutaneous ADR. Guidelines are proposed for performing these tests, and these include the use of appropriate negative control patients to avoid false-positive results.

Enoxaparin-associated dermal necrosis: a consequence of cross-reactivity with heparin-mediated antibodies

OBJECTIVE

To describe a patient with enoxaparin-induced dermal necrosis and to review previously reported cases of skin manifestations associated with low-molecular-weight heparins.

CASE SUMMARY

A 43-year-old white woman with adult respiratory distress syndrome developed localized dermal necrosis and thrombocytopenia secondary to subcutaneous administration of unfractionated heparin. Upper extremity thrombi that had developed after administration of subcutaneous heparin at an outside hospital were treated with subcutaneous enoxaparin. Although platelet counts remained stable during enoxaparin therapy, dermal necrosis developed at the injection site. Parenteral anticoagulant therapy was discontinued and the necrotic lesions secondary to enoxaparin resolved with minimal local care.

DISCUSSION

Numerous cases of dermal necrosis secondary to heparin administration have been reported while this reaction secondary to enoxaparin use has been reported only briefly. It has been postulated that dermal necrosis secondary to heparin is associated with heparin-induced thrombocytopenia and is a result of heparin-mediated thrombosis in the microvasculature. Antibodies to heparin have cross-reactivity with enoxaparin; therefore, dermal necrosis secondary to enoxaparin may occur by a similar mechanism.

CONCLUSIONS

Although enoxaparin-associated dermal necrosis appears to be a rare occurrence, we advise against the use of enoxaparin or other low-molecular-weight heparins in patients with a previous history of heparin-associated thrombocytopenia or heparin-induced dermal necrosis.

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

We report a case of delayed hypersensitivity to a low-molecular-weight heparin. The patient presented with eczema at the site of subcutaneous injections and allergy tests confirmed the clinical diagnosis. There were positive tests with 3 low-molecular-weight heparins and unfractionated subcutaneous calcium heparin but negative with intravenous sodium heparin. Although delayed hypersensitivity to low-molecular-weight heparins is rare, the possibility of cross-allergy to unfractionated heparin could be a therapeutic problem for some patients.

Serum sickness-like illness following streptokinase therapy. A case report

We report a patient who developed a serum sickness-like illness characterized by fever, arthritis, haematuria and a purpuric eruption 7 days following streptokinase therapy for myocardial infarction. Blood tests demonstrated increased circulating immune complexes. The skin involvement resulted in extensive, painful cutaneous infarction with secondary bacterial infection. Serum sickness is an uncommon but recognized complication of streptokinase therapy.

Continuous subcutaneous heparin infusion for treatment of Trousseau's syndrome

OBJECTIVE

To describe the use of continuous subcutaneous heparin infusion in the treatment of 2 cases of Trousseau's syndrome.

CASE SUMMARIES

Two patients with metastatic carcinoma presented to the hospital with acute coagulopathies consistent with a diagnosis of Trousseau's syndrome. In both cases conventional anticoagulant therapies proved to be impractical and ineffective.

DISCUSSION

Considerable literature suggests that oral anticoagulants such as warfarin are ineffective in the treatment of Trousseau's syndrome. Heparin is more effective for this purpose, although continuous intravenous infusion may prove difficult in the ambulatory setting. Intermittent subcutaneous injections of heparin or low-molecular-weight heparin may not provide reliable anticoagulation for the entire dosage interval. Although the use of continuous subcutaneous infusion of heparin has been used for anticoagulation during pregnancy, this is the first report of the use of sodium heparin administered by continuous subcutaneous infusion in the treatment of Trousseau's syndrome.

CONCLUSIONS

Continuous subcutaneous heparin infusion may be an effective option for the treatment of Trousseau's syndrome in the ambulatory setting.