Febrile Rash, Shock, and Hyperferritinaemia in A Young Woman: Navigating the Diagnostic Overlap of Hemophagocytic Lymphohistiocytosis, Toxic Shock, and Viral Exanthema.

Background: Fever, rash, and shock in adults pose diagnostic and therapeutic challenges. Markedly elevated ferritin often raises suspicion for hemophagocytic lymphohistiocytosis (HLH), yet hyperferritinaemia is also encountered in sepsis, adult-onset Still's disease (AOSD), and viral infections. Case report: We describe the case of a 27-year-old woman who developed a high fever, diffuse erythematous rash, hypotension, and markedly elevated ferritin levels. The initial differential diagnoses included toxic shock syndrome, HLH, AOSD, and viral exanthema. Extensive evaluations for infectious, autoimmune, and malignant diseases were negative. Imaging demonstrated gallstones with gallbladder wall inflammation, which was likely the trigger for the systemic inflammatory response. With supportive care and early multidisciplinary input, the patient made a full recovery without the need for immunosuppressive therapy. Conclusion: This case highlights the importance of contextualising ferritin elevation and maintaining a broad differential diagnosis. Serial laboratory trends, careful use of HLH scoring systems, and multidisciplinary collaboration prevented premature immunosuppression and ensured a favourable outcome. LEARNING POINTS: Hyperferritinaemia is a useful biomarker but highly non-specific and must be interpreted within the broader clinical context.Serial trends in inflammatory markers and use of scoring tools such as the HScore guide safe decision-making in suspected hemophagocytic lymphohistiocytosis.Early multidisciplinary review helps prevent unnecessary immunosuppression and ensures timely supportive care.