Case Study: Recurrent Pustular Lesions in an Immunocompromised Patient with Rheumatoid Arthritis

Case at a Glance

A 20-year-old immunocompromised female with a history of rheumatoid arthritis presented with recurrent, painful, pus-filled lesions on her hands and legs. The case highlights the diagnostic challenge of differentiating between a primary infectious process and a cutaneous manifestation of her underlying autoimmune disease.

Patient's Story

The patient is a 20-year-old female with a known history of rheumatoid arthritis (RA) for which she is on immunosuppressive therapy. She presented with a several-month history of recurrent, painful skin lesions affecting her fingers and legs. She reported that as soon as one lesion resolves, another appears. The lesions on her legs were described as larger, boil-like abscesses, consistent with folliculitis. The lesions on her fingers were distinct: smaller, intensely painful pustules that initially resembled a splinter. However, upon manipulation, they would rupture to reveal a small cavity filled with purulent discharge, with no foreign body present. The patient noted a possible correlation between the appearance of these lesions and a localized flare of arthralgia in the affected limb, even in joints not typically symptomatic from her RA.

Initial Assessment

On presentation, the patient was distressed by the pain and recurrence of the lesions. She had been self-managing by draining the pustules, cleaning the area, and applying an over-the-counter antiseptic cream under a dressing. She also admitted to occasional self-medication with oral antibiotics left over from previous prescriptions. Her hygiene regimen was noted as meticulous, with frequent hand washing and daily showering. Clinical examination of a representative lesion on her finger revealed a small, erythematous papule with a central pustule that crusted over after drainage. The differential diagnosis was broad, including recurrent bacterial infection (e.g., Staphylococcal), Impetigo Contagiosa, or a cutaneous manifestation of her underlying RA, such as a neutrophilic dermatosis.

The Diagnostic Journey

Given the patient's immunocompromised status, the first step was to rule out an infectious etiology. A recommendation was made for immediate microbiological analysis. This would involve obtaining a swab from the purulent discharge of an active lesion for Gram stain, bacterial culture, and sensitivity testing. This is crucial to identify the causative organism (e.g., Staphylococcus aureus, including MRSA) and guide appropriate antibiotic therapy. Concurrently, a consultation with her managing rheumatologist was advised. If the bacterial cultures returned negative, the lesions would be considered more likely a manifestation of her underlying autoimmune condition, which would require a re-evaluation of her systemic RA therapy.

Final Diagnosis

Pending definitive culture results, the primary working diagnosis was Recurrent Pyoderma/Abscess Formation secondary to Immunosuppression. A key differential to be excluded was a Neutrophilic Dermatosis associated with her rheumatoid arthritis. The recurrent nature and location were highly suspicious of a persistent bacterial colonization.

Treatment Plan

The immediate management plan focused on halting inappropriate self-treatment and establishing a proper diagnostic and therapeutic pathway:

1. Cease Self-Medication: The patient was instructed to stop taking unprescribed oral antibiotics to prevent antibiotic resistance and adverse effects.
2. Diagnostic Workup: An urgent appointment with her general practitioner was scheduled to obtain a bacterial swab for culture and sensitivity before any new antimicrobial therapy was initiated.
3. Topical Management: Advised to use a local antiseptic wash (e.g., chlorhexidine) for wound care. If infection was confirmed, targeted topical antibiotic therapy (e.g., mupirocin) would be prescribed.
4. Systemic Therapy: Oral antibiotics were to be reserved for severe or non-resolving infections and prescribed only based on culture sensitivity results.
5. Referral: A referral to both a dermatologist and her rheumatologist was recommended for a comprehensive evaluation and long-term management strategy.

Outcome and Follow-up

The patient was counseled on the importance of a definitive diagnosis. Follow-up was scheduled to review the microbiology results and coordinate care with her rheumatology team. Long-term management would likely involve addressing any identified bacterial colonization (e.g., decolonization protocols for MRSA/MSSA) and potentially adjusting her immunosuppressive regimen to better control her autoimmune disease without predisposing her to further infections. The goal was to break the cycle of recurrence and manage both her skin and joint health effectively.