A22-15 Erythema Nodosum as an Initial Presentation of Sarcoidosis: Diagnostic and Prognostic Implications

Abstract Rationale Sarcoidosis is a granulomatous, multisystem inflammatory disease of unknown etiology that most frequently affects the lungs and skin. Erythema nodosum (EN) is the most common non-specific cutaneous manifestation, reported in up to 25% of sarcoidosis cases and often associated with a favorable prognosis. This study describes a case of biopsy-confirmed sarcoidosis initially presenting with EN and examines the diagnostic and clinical significance of this presentation. Methods A 54-year-old male with a medical history of hypertension, hyperlipidemia, and hypothyroidism presented with a 10-day history of painful, erythematous nodules on both lower extremities. Comprehensive laboratory, radiographic, and microbiological evaluations were performed to identify infectious, autoimmune, and inflammatory etiologies. Chest computed tomography (CT) and bronchoscopy with transbronchial needle aspiration (TBNA) were conducted to confirm the diagnosis. Results Physical examination revealed tender, nodular erythematous lesions with 1+ pitting edema in the bilateral lower extremities. Laboratory findings demonstrated elevated erythrocyte sedimentation rate (ESR 92 mm/hr) and C-reactive protein (CRP 21 mg/L), mild leukocytosis (13.8 ×109/L), transaminitis (AST 130 U/L, ALT 150 U/L), and acute kidney injury (creatinine 1.4 mg/dL). Chest CT revealed multiple sub centimeter pulmonary nodules with mediastinal and hilar lymphadenopathy. Extensive infectious, rheumatologic, and autoimmune panels—including ANA, ANCA, ACE, HLA-B27, hepatitis panel, and QuantiFERON-TB—were negative. Histopathologic examination of mediastinal lymph node biopsy demonstrated noncaseating granulomas with a CD4:CD8 ratio of 10.8, confirming sarcoidosis. The patient’s cutaneous and systemic symptoms improved with nonsteroidal anti-inflammatory drugs and acetaminophen alone. No corticosteroids were required. The patient remained clinically stable at follow-up, with no evidence of extrapulmonary progression. Conclusions Erythema nodosum can serve as an early clinical clue to sarcoidosis and is often associated with a self-limiting, favorable disease course. Recognition of EN in the appropriate clinical context can expedite diagnosis and guide a conservative management strategy. This case underscores the importance of comprehensive diagnostic evaluation to distinguish sarcoidosis-related EN from other inflammatory or infectious etiologies and supports the role of non-immunosuppressive management in cases with limited organ involvement. This abstract is funded by: None