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From the Intensive Care Unit, Department of Medicine (Leclair, St-Pierre), Centre Hospitalier Universitaire de Sherbrooke; and the Dermatology Division (Maynard), Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Que.
Correspondence to: Dr. Catherine St-Pierre, Centre Hospitalier Universitaire de Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke QC J1H 5N4; fax 819 820-6406; Catherine.St-Pierre{at}USherbrooke.ca
A 53-year-old man was transferred to our intensive care unit for a generalized exanthem with systemic inflammatory response syndrome. His medical history included a possible disseminated infection of herpes zoster 15 years before the current admission. He had no history of psoriasis, cutaneous drug reaction, immune suppression or heart disease. Before the current incident, he had not been using any prescribed or over-the-counter medications.
Seven days before admission, the patient was bitten on his finger by a spider. He reported pain at the site, and there was a necrotic crust. His primary care physician prescribed cefprozil. A few hours after the first dose, a rash developed. The rash was described as a generalized exanthem with nonfollicular superficial pustules and fever. Based on a working diagnosis of recurrent herpes zoster, he was given famciclovir.
Two days before admission to our intensive care unit, the patient was admitted to another centre with high fever, fatigue and persistent skin lesions. Because of fever, leukocytosis and pustules, an infectious cause was suspected. Antibiotic coverage was broadened to include piperacillin–tazobactam and moxifloxacin. The results of tests for infectious and immunosupressive diseases were negative. A computerized tomography (CT) scan of the patient’s chest showed alveolar opacities with a ground-glass appearance in both upper lungs. A CT scan of the patient’s abdomen showed small nonspecific opacities in his liver. The patient was then transferred to our centre.
When the patient arrived at our centre, he had a fever (39.9 °C) and was tachycardic (130 beats/min) and hypotensive (90/80 mm Hg). His oxygen saturation was 90% on room air. There was no jugular venous distension. The results of a cardiac examination were unremarkable, except for tachycardia. More than 80% of his skin, including his face and scalp, was affected by a generalized erythema with multiple small nonfollicular pustules. An examination of his mucous membranes showed redness of his tongue. He did not have the Nicolsky sign. (The Nikolsky sign is detected by applying pressure to the skin, which causes intraepidermal cleavage that allows the superficial skin to slip free from the deeper layer. It is mainly seen with bullous diseases and toxic epidermal necrolysis.)
Important laboratory results are shown in Table 1. An electrocardiogram showed only sinus tachycardia. We suspected a cutaneous drug reaction. The main diagnoses considered at that time were Stevens–Johnson syndrome or toxic epidermal necrolysis and acute generalized exanthematous pustulosis associated with severe systemic inflammatory response syndrome. The results of the CT scan of the patient’s chest were suggestive of an acute lung injury. An infectious cause was not likely because all of the cultures were negative. Antibiotics were discontinued, and fluid resuscitation was initiated. A few hours after admission, our patient developed pulmonary edema with acute respiratory failure. Noninvasive positive pressure ventilation and diuretic therapy were successfully started. An echocardiography performed the next day showed reduced left ventricular ejection fraction of 30% (normal > 60%) with diffuse hypokinesis.
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A skin biopsy showed spongiform intraepidermal pustules and acanthosis, dermal edema with mixed inflammatory cells and neutrophilic perivascular infiltrates (Figure 1). We determined the likelihood of acute generalized exanthematous pustulosis by use of the EuroSCAR study group’s scoring system, 1 which can be used to identify cases of acute generalized exanthematous pustulosis based on morphology, course and histology of the skin reaction (Table 2). Our patient had a score of 11, which indicates a definite diagnosis of acute generalized exanthematous pustulosis.
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Within 72 hours after discontinuing antibiotics, our patient’s left ventricular ejection fraction normalized. The cutaneous lesions resolved within a few days, followed by widespread desquamation. Because of his clinical recovery, we decided not to give glucocorticoid therapy.
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Discussion |
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Clinical findings
Acute generalized exanthematous pustulosis is characterized by superficial sterile pustules with spontaneous healing. The cutaneous eruption usually begins with edematous erythema in the intertriginous areas or in the face that disseminates acutely with burning and itching. Dozens of pinhead-sized nonfollicular pustules develop against the background of this erythema (Figure 2). The rash is often accentuated in the major skin folds. Mucous membrane involvement occurs in fewer than 20% of cases and is usually mild and limited to 1 region (usually the mouth). Cutaneous lesions resolve within a few days and are followed by a characteristic pin-point desquamation.
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Skin biopsies typically show spongiform subcorneal or intraepidermal pustules, edema of the papillary dermis and perivascular infiltrates with neutrophils and exocytosis of some eosinophils. 3 Vasculitis and necrosis of keratinocytes may be present but psoriasiform changes are absent.
Cutaneous manifestations are often accompanied by systemic symptoms such as high-grade fever, increased neutrophil count (in 80% of cases) and mild eosinophilia (in 30% of cases). 4 Lymphadenopathy has also been reported. 5 Dysfunction of the internal organs is not expected, although mild acute renal failure occurs in about one-third of patients. Mild hepatic dysfunction and acute renal failure that requires hemodialysis have also been reported. 5 Dysfunction of multiple organ systems is rare, and only a few cases in the literature report hemodynamic disturbances. 6–8 We believe that the abnormalities observed on the initial chest scans for our patient were related to cardiogenic pulmonary edema with systemic inflammatory response syndrome-associated increased vascular permeability. The severity and prolonged duration of the inflammatory response in our patient probably led to cardiac dysfunction.
Causes
More than 90% of cases of acute generalized exanthematous pustulosis are believed to be caused by drugs, most frequently by aminopenicillins, macrolides and quinolones. 2 The syndrome has also been described in relation to spider bites. 9 Because our patient was exposed to cefprozil and was bitten by a spider, we cannot know with certainty what caused his reaction. Based on the temporal relation of the disease to drug exposure, we believe that cefprozil was the most likely cause.
The pathophysiological mechanisms of acute generalized exanthematous pustulosis are unclear, but an immunologic recall phenomenon has been suggested. Patch testing may help identify the responsible drug; however, a positive reaction was found in only 7 of 14 patients with acute generalized exanthematous pustulosis in a study of severe cutaneous drug reactions. 10
A cornerstone of therapy for drug-induced skin reactions is discontinuation of the causative drug. The overall prognosis for acute generalized exanthematous pustulosis is good with a self-limiting course. 4 Glucocorticoids are not usually necessary because of the self-limiting course of the reaction.
Differential diagnosis
Physicians must differentiate between Stevens–Johnson syndrome or toxic epidermal necrolysis and acute generalized exanthematous pustulosis. Patients with Stevens–Johnson syndrome or toxic epidermal necrolysis should be treated like patients with major burns. A broad multidisciplinary team is often required to care for the extensive cutaneous, mucosal and ophthalmologic involvement. Sequelae, primarily dermatologic and ophthalmologic, can occur. Mortality, mainly because of sepsis, among patients with Stevens–Johnson syndrome or toxic epidermal necrolysis is as high as 35%–50%, while the mortality is 5% among those with acute generalized exanthematous pustulosis. The clinical features that can be used to differentiate between these conditions are shown in Table 3.
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The clinical course of an acute generalized exanthematous pustulosis skin reaction is characteristic. 2 Lesions usually occur within a few hours after exposure and resolve quickly over a few days. In contrast, there is usually a longer delay of 1 to 3 weeks after exposure in Stevens–Johnson syndrome and toxic epidermal necrolysis.
The confluence of the pustules in acute generalized exanthematous pustulosis may result in a positive Nikolsky sign and lead to an erroneous diagnosis of Stevens–Johnson syndrome or toxic epidermal necrolysis. Figure 2 and Figure 3 show characteristic rashes of acute generalized exanthematous pustulosis and Stevens–Johnson syndrome.
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Acute generalized exanthematous pustulosis has a different spectrum of causative drugs then Stevens–Johnson syndrome and toxic epidermal necrolysis. Although antibiotics are important causes of both types of reactions, Stevens–Johnson syndrome and toxic epidermal necrolysis are associated more frequently with sulfonamides, and acute generalized exanthematous pustulosis is more frequently associated with aminopenicillins. Antiepileptic drugs and allopurinol do not play an important role in the pathogenesis of acute generalized exanthematous pustulosis, whereas they have been connected with Stevens–Johnson syndrome and toxic epidermal necrolysis. 2
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Competing interests: None declared.
Previously published at www.cmaj.ca
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