D2.307 - Diagnostic characterization of symmetrical drug-related intertriginous and flexural exanthema (SDRIFE): Case series from a tertiary care hospital and literature review

Symmetrical drug-related intertriginous and flexural exanthema (SDRIFE) is a rare, delayed-type hypersensitivity reaction characterized by sharply demarcated erythema in flexural areas following systemic drug exposure. Although generally self-limiting, SDRIFE's diagnostic challenges complicate effective management.

Objective: This study aims to provide a detailed characterization of SDRIFE through a large case series and literature review, focusing on diagnostic approaches, clinical presentations, and implicated drugs to improve patient outcomes.

Methods: A retrospective, observational study was conducted at a tertiary care hospital from 2018 to 2024, encompassing 41 cases of SDRIFE. Data collected included demographics, clinical features, implicated drugs, latency periods, and resolution times. Diagnostic tests performed included drug provocation tests (DPT), lymphocyte transformation tests (LTT), and intradermal tests.

A total of 41 patients with a clinical diagnosis of SDRIFE were included in our study. A definitive etiological diagnosis was established in 11 patients (26.8%) (Table 1). In 8 patients (19.5%), no diagnostic tests aimed at identifying the etiology were performed, while in 22 patients (53.7%), some diagnostic tests were conducted but did not lead to a definitive etiological diagnosis.

The mean age of patients was 66.6 years, with no significant gender predominance. Polypharmacy was frequent, with beta-lactam antibiotics and iodinated contrast agents being the most common triggers (All drugs listed in Figure 1). Notably, nine previously unreported drugs were identified as causes.

DPT confirmed causality in six cases, while LTT was instrumental in three complex cases. Skin tests had limited sensitivity, with patch and prick tests yielding negative results in all cases. Biopsy findings were non-specific but consistent with delayed hypersensitivity.

This study, presenting the largest reported case series of SDRIFE, underscores the importance of systematic medication reviews and the development of standardized diagnostic protocols. DPT remain the gold standard for etiological confirmation, while LTT provide valuable support in complex cases, particularly where DPT may not be feasible. A targeted approach to drug avoidance, focusing on the implicated agent rather than entire pharmacological classes, can significantly expand therapeutic options and improve patient care. These findings highlight the immune-mediated nature of SDRIFE and call for further research to deepen the understanding of its pathophysiology and improve diagnostic strategies.