In a patient with systemic lupus erythematosus and ulcerated skin lesions, should I consult an infectious disease specialist before initiating or intensifying immunosuppressive therapy?

Should You Consult Infectious Disease in SLE with Ulcerated Skin Lesions?

Yes, you should consult infectious disease before initiating or intensifying immunosuppressive therapy in a patient with systemic lupus erythematosus and ulcerated skin lesions, as distinguishing between infection and lupus flare is critical, and infections remain a leading cause of mortality in SLE patients. 1

Why Infectious Disease Consultation is Essential

The Diagnostic Dilemma in SLE

• A common and critical caveat is distinguishing between a lupus flare and an acute infection; judicious use of corticosteroids and cytotoxic drugs is essential in limiting infectious complications. 1
• Ulcerated skin lesions in SLE patients can represent either disease activity (lupus-specific cutaneous manifestations, vasculitis, or bullous lesions) or superinfection of existing lesions. 2, 3
• Making the wrong diagnosis and intensifying immunosuppression in the presence of active infection can lead to severe morbidity and mortality. 1, 4

High Infection Risk in SLE Population

• SLE patients are at high risk for both typical bacterial infections (pneumonia, urinary tract infection, cellulitis, sepsis with Gram-positive and Gram-negative organisms) and opportunistic infections, especially when treated with immunosuppressive agents. 1
• Both the innate and adaptive branches of the immune system are compromised in SLE, independent of treatment. 4
• Risk factors for infection include severe flares, active renal disease, and treatment with moderate or high doses of corticosteroids and/or immunosuppressive agents. 1

Pre-Immunosuppression Infectious Disease Evaluation

Mandatory Screening Before Treatment Intensification

• Identification and treatment of chronic infections such as tuberculosis, hepatitis B, or HIV are important prior to institution of immunosuppression to prevent reactivation or exacerbation of the infection. 1
• An infectious disease specialist can systematically evaluate for latent infections that may reactivate with immunosuppression. 1

Evaluation of Current Ulcerated Lesions

• Infectious disease consultation should include assessment for bacterial superinfection of ulcerated lesions, which is a common complication. 2
• Consider wound cultures, blood cultures if systemic signs present, and evaluation for atypical organisms in immunocompromised patients. 1
• The specialist can help determine if empiric antimicrobial therapy is needed before immunosuppression intensification. 1

Diagnostic Approach to Ulcerated Lesions

Skin Biopsy is Essential

• Skin biopsy for histological analysis is the gold standard diagnostic test and should not be skipped even when clinical features are highly suggestive, as the differential diagnosis is broad. 5
• Perform either complete excision of small lesions or an incisional biopsy (at least 4 mm punch) to ensure adequate tissue for histopathological workup. 5
• Ensure adequate biopsy depth to capture both superficial and deep dermal changes. 5

Consider Multiple Etiologies

• Ulcerated lesions in SLE can represent: bullous eruptions (including bullous SLE or vasculitis-associated bullae), cutaneous vasculitis, pyoderma gangrenosum, or superinfection of discoid lupus lesions. 2, 3
• Bullous skin eruptions occurred in 6-10% of SLE patients in observational studies, with various underlying causes. 2, 3

Parameters to Help Differentiate Infection from Flare

• C-reactive protein (CRP) and adhesion molecules may help differentiate infectious disease from an exacerbation of lupus disease activity. 1
• CRP is typically elevated disproportionately in infection compared to lupus flare alone. 1
• However, these parameters are not definitive, which is why specialist consultation is valuable. 1

Common Pitfalls to Avoid

• Do not rely solely on clinical appearance, as many inflammatory and infectious disorders can present with similar features. 5
• Do not assume all new skin lesions represent lupus activity without ruling out infection, especially in patients already on immunosuppression. 1
• Avoid intensifying immunosuppression empirically without infectious disease clearance when ulcerated lesions are present. 1
• If there is change in clinical morphology of lesions or lack of response to treatment, repeat biopsy is recommended. 5, 6

When to Proceed Without Delay

• If infectious disease consultation will cause significant delay and the clinical picture strongly suggests pure lupus activity (e.g., classic malar rash, photosensitive dermatitis without ulceration), treatment may proceed with close monitoring. 7, 3
• However, ulcerated lesions specifically warrant heightened suspicion for infection or superinfection, making consultation appropriate in this scenario. 2