P036 Haemophagocytic lymphohistiocytosis as the first presentation of SLE and relapsing polychondritis overlap: a rare presentation of a rare condition

Haemophagocytic lymphohistiocytosis (HLH) is a rare but life-threatening condition due to a hyperinflammatory immune response. It can occur secondary to infections, malignancies or rheumatological disorders. Relapsing polychondritis (RP) is also a rare condition with systemic manifestations characterized by inflammation in hyaline cartilages in the body. Approximately one-third of patients with RP have an underlying autoimmune, haematological or malignant disorder, however association between RP and SLE is extremely rare (less than 1%). Additionally, the presentation of HLH triggered by RP is exceptionally rare posing significant diagnostic and therapeutic challenges.

Case summary: A 64-year-old woman with no significant medical history, presented to the emergency department with a five-month history of fever, weight loss and inflammatory polyarthritis. She also reported swelling and erythema of both ear lobes, a malar rash and a non-specific itchy, scaly rash over her abdomen and breasts. Initial investigations revealed a pancytopenia (Hb: 103 g/L, WBC: 0.4 x10⁹/L, Platelets: 11 x10⁹/L). Further testing revealed p ANCA positive, MPO 8.2 IU/ml (0-3.5), ANA 1:160-320, homogeneous, dsDNA 178 IU/mL (0-9), C3 0.68g/L (0.75-1.65), C4 0.03g/L (0.14-0.54), cryoglobulins negative, antiphospholipid screen negative, Ro+, Ro52+, Ro60+ and initial ferritin 1925µg/L. NT-proBNP 2605ng/L(0-400) and an echocardiogram confirmed a normal ejection fraction 65%. Blood cultures were negative as was EBV, CMV, HIV and HHV8 serology. The bone marrow aspirate did not show haemophagocytosis or any haematological malignancies. The pancytopenia deteriorated and ferritin rose rapidly to > 33500 µg/L. Further ferritin dilutions were requested and the maximum recorded ferritin was 178,128 µg/L with a H score of 204, consistent with HLH. She was commenced on intravenous methylprednisolone initially. Anakinra was commenced with prophylactic acyclovir and cotrimoxazole and ciclosporin was added. Following additional treatment with IV Immunoglobulin and rituximab, her clinical condition started to improve. She then developed new-onset confusion. An MRI brain was normal. A lumbar puncture revealed CSF protein 0.56g/L(0.15-0.6), glucose 3.3mmol/L and HSV-1 PCR detected consistent with HSV encephalitis. She was commenced on a 14 day course of intravenous acyclovir and has improved clinically. A slow taper of Anakinra was required over 7 weeks.

The pancytopenia has resolved, complement levels have normalised with the latest ferritin 1354µg/L. Genetic testing for the UBA1 gene mutation was negative.

This was a first presentation of an SLE-RP overlap connective tissue disorder manifesting as HLH. Requesting increased ferritin dilutions enabled more accurate assessment of response to treatment. Prophylactic use of acyclovir reduced the severity of presentation of HSV encephalitis. Early recognition, a high index of clinical suspicion for HLH, and a multidisciplinary approach are critical for prompt, effective treatment. This case demonstrates the importance of intensive immunosuppression in autoimmune causes of HLH and the necessity of a prolonged wean of anakinra, resulting in a favorable outcome.

M. Kerols: None. N. Abdellaziz: None. C.S. Jayasinghe: None. A. Vijayan: None. D. De Lord: None. K. Abdulmalek: None.