Peripheral Axonal Neuropathy in Hemophagocytic Lymphohistiocytosis Secondary to Rickettsia conorii Infection

Hemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal hyperinflammatory syndrome characterized by dysregulated immune activation and systemic inflammation. Secondary HLH is often triggered by infections, with Rickettsia conorii being an infrequently reported cause. Peripheral axonal neuropathy is a rare and poorly understood complication of HLH. We present the case of a 58-year-old male who presented with fever, diarrhea, a maculopapular rash involving the palms and soles, and progressive lower limb weakness. Laboratory findings revealed pancytopenia, hyperferritinemia, elevated soluble CD25, liver cytolysis, hypofibrinogenemia, and raised inflammatory markers. Serological testing confirmed Rickettsia conorii infection. The patient fulfilled six of the eight HLH-2004 diagnostic criteria, establishing the diagnosis of secondary HLH. Treatment was initiated with intravenous dexamethasone and doxycycline. During hospitalization, the patient developed severe hypoxemic respiratory failure, paraplegia, and acute sensory loss. The neurological evaluation confirmed peripheral axonal neuropathy linked to Rickettsia conorii infection, which preceded the development of HLH. After 21 days of doxycycline therapy, the patient was discharged to a rehabilitation facility with full neurological recovery. This case underscores the rarity of Rickettsia conorii as a trigger for HLH and highlights the exceptional occurrence of peripheral axonal neuropathy as a complication. The singularity of this case reinforces the importance of a correct and early diagnosis of HLH, which can have atypical and severe complications but also a successful outcome.