Hemophagocytic lymphohistiocytosis triggered by relapsing polychondritis: A case report.

Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening disorder caused by abnormal histiocytes and T cell activation. In adults, it is predominantly associated with infections, cancers, and autoimmune diseases. Relapsing polychondritis (RP), another rare disease, is diagnosed based on symptoms without specific tests, featuring cartilage inflammation characterized by swelling, redness, and pain, rarely inducing HLH.

Case summary: A 74-year-old woman visited the emergency room with a fever of 38.6 °C. Blood tests, cultures, and imaging were performed to evaluate fever. Results showed increased fluorescent antinuclear antibody levels and mild cytopenia, with no other specific findings. Imaging revealed lymph node enlargement was observed; however, biopsy results were inconclusive. Upon re-evaluation of the physical exam, inflammatory signs suggestive of RP were observed in the ears and nose, prompting a tissue biopsy for confirmation. Simultaneously, persistent fever accompanied by cytopenia prompted a bone marrow examination, revealing hemophagocytic cells. After finding no significant results in blood culture, viral markers, and tissue examination of enlarged lymph nodes, HLH was diagnosed by RP. Treatment involved methylprednisolone followed by azathioprine. After two months, bone marrow examination confirmed resolution of hemophagocytosis, with normalization of hyperferritinemia and pancytopenia.

Conclusion: Thorough physical examination enabled diagnosis and treatment of HLH triggered by RP in patients presenting with fever of unknown origin.