Extreme Hyperferritinemia in a Filipino Male Patient with Adult Onset Still’s Disease: A Case Report

Background: Elevated serum ferritin is more commonly due to reactive causes such as infection, hepatic disorders, rheumatologic conditions, and malignancy than true iron overload. Extreme hyperferritinemia (>10,000 ng/mL), on the other hand, should prompt consideration of rare conditions such as adult-onset Still’s disease (AOSD) or hemophagocytic lymphohistiocytosis. This paper aims to present the case of the highest reported extreme hyperferritinemia (actual level 256,000 ng/mL) in a patient eventually diagnosed with adult onset Still’s Disease (AOSD). Case Presentation: A 55-year-old male, Filipino, was admitted due to acute onset fever and shortness of breath. He was initially assessed to have community-acquired pneumonia and a suspect for coronavirus disease 2019 (COVID-19), hence inflammatory markers were requested. Ferritin was notably elevated at 44,255 ng/mL. He eventually tested negative for COVID-19 RT-PCR. He was investigated for other causes of markedly elevated ferritin levels. His complete blood count (CBC) only showed leukocytosis with no peripheral blasts, iron level and liver function tests were normal, HIV immunoassay was negative, ANA was 1:80 speckled with normal complement level, rheumatoid factor negative, and positron emission tomography (PET) scan revealed presence of lymphadenopathies and did not show solid tumors. He was treated for urinary tract infection and pneumonia but still had intermittent fever and increasing ferritin trend, with the highest documented level at 256,000 ng/mL. Fulfilling the Yamaguchi criteria, he was managed as a case of severe AOSD and received tocilizumab. He had lysis of fever and decreasing trend of ferritin levels thereafter, with ferritin level of 34,184 ng/mL three weeks after tocilizumab infusion. He was discharged and improved with prednisone and methotrexate as home medications. Conclusion: To our knowledge, the highest level of extreme hyperferritinemia recorded in literature as of 2016 is 143,931 ng/mL, which was associated with hematologic malignancy. This case documents the highest noted