Generalized Fixed Drug Eruptions Require Urgent Care: A Case Series

Comment

Presentation of FDEs—A fixed drug eruption manifests with 1 or more well-demarcated, red or violaceous, annular patches that resolve with postinflammatory hyperpigmentation; it occasionally may manifest with bullae. Initial eruptions may occur up to 2 weeks following medication exposure, but recurrent eruptions usually happen within minutes to hours later. They often are in the same location as prior lesions. A fixed drug eruption can be solitary, scattered, or generalized; a generalized FDE typically demonstrates multiple bilateral lesions that may itch, burn, or cause no symptoms. Patients can experience an FDE at any age, though the median age is reported as 35 to 60 years of age.¹ A fixed drug eruption usually occurs after ingestion of oral medications, though there have been a few reports with iodinated contrast.² Well-known culprits include antibiotics (eg, sulfamethoxazole-trimethoprim, tetracyclines, penicillins/cephalosporins, quinolones, dapsone), nonsteroidal anti-inflammatory drugs, acetaminophen (eg, paracetamol), barbiturates, antimalarials, and anticonvulsants. It also can occur with vaccines or with certain foods (fixed food eruption).^3,4 Clinicians may try an oral drug challenge to identify the cause of an FDE, but in patients with a history of a generalized FDE, the risk for developing an increasingly severe reaction with repeated exposure to the medication is too high.⁵

Histopathology—Patch testing at the site of prior eruption with suspected drug culprits may be useful.⁶ Histopathology of FDE typically demonstrates vacuolar changes at the dermoepidermal junction with a lichenoid lymphocytic infiltrate. Early lesions often show a predominance of eosinophils. Subepidermal clefting is a feature of the bullous variant. In an active lesion, there are large numbers of CD8+ T lymphocytes expressing natural killer cell–associated molecules.⁷ The pathologic mechanism is not well understood, though it has been hypothesized that memory CD8+ cells are maintained in specific regions of the epidermis by IL-15 produced in the microenvironment and are activated upon rechallenge.⁷Considerations in Generalized Bullous FDE—Generalized FDE is defined in the literature as an FDE with involvement of 3 of 6 body areas: head, neck, trunk, upper limbs, lower limbs, and genital area. It may cover more or less than 10% of the body surface area.^8-10 Although an isolated FDE frequently is asymptomatic and may not be cause for alarm, recurring drug eruptions increase the risk for development of generalized bullous FDE. Generalized bullous FDE is a rare subset. It is frequently misdiagnosed, and data on its incidence are uncertain.¹¹ Of note, several pathologies causing bullous lesions may be in the differential diagnosis, including bullous pemphigoid; pemphigus vulgaris; bullous SLE; or bullae from cutaneous lupus, staphylococcal scalded skin syndrome, erythema multiforme, or SJS/TEN.¹² When matched for body surface area involvement with SJS/TEN, generalized bullous FDE shares nearly identical mortality rates¹⁰; therefore, these patients should be treated with the same level of urgency and admitted to a critical care or burn unit, as they are at serious risk for infection and other complications.¹³

Clinical history and presentation along with histopathologic findings help to narrow down the differential diagnosis. Clinically, generalized bullous FDE does not affect the surrounding skin and manifests sooner after drug exposure (1–24 hours) with less mucosal involvement than SJS/TEN.⁹ Additionally, SJS/TEN patients frequently have generalized malaise and/or fever, while generalized bullous FDE patients do not. Finally, patients with generalized bullous FDE may report a history of a cutaneous eruption similar in morphology or in the same location.

Histopathologically, generalized bullous FDE may be similar to FDE with the addition of a subepidermal blister. Generalized bullous FDE patients have greater eosinophil infiltration and dermal melanophages than patients with SJS/TEN.⁹ Cellular infiltrates in generalized bullous FDE include more dermal CD41 cells, such as Foxp31 regulatory T cells; fewer intraepidermal CD561 cells; and fewer intraepidermal cells with granulysin.⁹ Occasionally, generalized bullous FDE causes full-thickness necrosis. In those cases, generalized bullous FDE cannot reliably be distinguished from other conditions with epidermal necrolysis on histopathology.¹³

FDE Diagnostics—A cytotoxin produced by cytotoxic T lymphocytes, granulysin can be measured to aid in diagnosis of FDE, though this test may not be widely available. High levels of granulysin in the blister fluid and serum can be used to distinguish SJS/TEN, erythema multiforme, and localized and generalized bullous FDE from other non–cytotoxic T lymphocyte–mediated bullous skin disorders, such as bullous pemphigoid, pemphigus, and bullous SLE.¹⁴ Blister granulysin levels are notably lower in generalized bullous FDE than in SJS/TEN.^9,14 Chen et al¹⁴ also found that granulysin levels can be used to gauge disease progression given that the levels sharply decrease after patients have reached maximal skin detachment.

Management—Avoidance of the inciting drug often is sufficient for patients with an FDE, as demonstrated in patient 2 in our case series. Clinicians also should counsel patients on avoidance of potential cross-reacting drugs. Symptomatic treatment for itch or pain is appropriate and may include antihistamines or topical steroids. Nonsteroidal anti-inflammatory drugs may exacerbate or be causative of FDE. For generalized bullous FDE, cyclosporine is favored in the literature^15,16 and was used to successfully treat both patients 1 and 3 in our case series. A short course of systemic corticosteroids or intravenous immunoglobulin also may be considered. Mild cases of generalized bullous FDE may be treated with close outpatient follow-up (patient 1), while severe cases require inpatient or even critical care monitoring with aggressive medical management to prevent the progression of skin desquamation (patient 3). Patients with severe oral lesions may require inpatient support for fluid maintenance.

Lupus History—Two patients in our case series had a history of lupus. Lupus itself can cause primary bullous lesions. Similar to FDE, bullous SLE can involve sun-exposed and nonexposed areas of the skin as well as the mucous membranes with a predilection for the lower vermilion lip.¹⁷ In bullous SLE, tense subepidermal blisters with a neutrophil-rich infiltrate form due to circulating antibodies to type VII collagen. These blisters have an erythematous or urticated base, most commonly on the face, upper trunk, and proximal extremities.¹⁸ In both SLE with skin manifestations and lupus limited to the skin, bullae may form due to extensive vacuolar degeneration. Similar to TEN, they can form rapidly in a widespread distribution.¹⁷ However, there is limited mucosal involvement, no clear drug association, and a better prognosis. Bullae caused by lupus will frequently demonstrate deposition of immunoproteins IgG, IgM, IgA, and complement component 3 at the basement membrane zone in perilesional skin on direct immunofluorescence. However, negative direct immunofluorescence does not rule out lupus.¹² At the same time, patients with lupus frequently have comorbidities requiring multiple medications; the need for these medications may predispose patients to higher rates of cutaneous drug eruptions.¹⁹ To our knowledge, there is no known association between FDE and lupus.

Conclusion

Patients with acute eruptions following the initiation of a new prescription or over-the-counter medication require urgent evaluation. Generalized bullous FDE requires timely diagnosis and intervention. Patients with lupus have an increased risk for cutaneous drug eruptions due to polypharmacy. Further investigation is necessary to determine if there is a pathophysiologic mechanism responsible for the development of FDE in lupus patients.