353. A case of MPO-ANCA vasculitis complicated by haemophagocytic lymphohistiocytosis
Creators: name: Pek Ghe Tan1
Publisher: name: Zenodo
Year: 2022
Subjects: Vasculitis
ANCA
Abstracts
Giant Cell Arthritis
MPA
GPA
EGPA
Takayasu
IgA vasculitis

description: <strong>Presentation of Case: </strong>A 34 year old white female presented with fever and rigors. Her history was complex with diagnosis of myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) vasculitis 16 years earlier. At that time, presenting with weight loss, rash, haematoproteinuria and very high titre perinuclear-ANCA and MPO antibodies. In addition, positive speckled anti-nuclear antibody, anti-smith and anti-ribonucleoprotein. Kidney biopsy showed crescentic nephritis but with immune complexes. She developed pulmonary haemorrhage requiring plasma exchange, IV methylprednisolone and cyclophosphamide. She later experienced atypical sympto including alopecia, angioedema, bilateral hip avascular necrosis, Raynaud’s phenomenon and cold-induced urticaria. She stopped mycophenolate maintenance 9 years post-diagnosis until a relapse with haematoproteinuria and pauci-immune focal segmental glomerulonephritis on biopsy, treated with rituximab and azathioprine maintenance, selected due to plans for pregnancy. Her anti-MPO antibody level remained above the maximum lab reported level throughout the entire clinical course. On this admission she developed persistent pyrexia, 10 days post spinal surgery for disc protrusion. Her clinical status deteriorated, developing headache, abdominal pain, facial swelling and a petechial rash. <strong>Diagnostic Testing: </strong>She became pancytopenic. (Haemoglobin: 88g/L; white cell count: 1.7 x10ˆ9/L; absolute neutrophil count: 1.0 x10ˆ9/L; platelets: 12 x10ˆ9/L). CRP: 227mg/L. Fibrinogen 2.8g/L (from 5.5). ESR 35mm/h (from 55). Further testing revealed ferritin 7284ug/L, LDH 933U/L, triglycerides 5.87mmol/L and liver enzyme dysfunction. Serum creatinine: 57mmol/L. Urinary PCR: 194mg/mmol. Blood, urine and sputum cultures were negative. Respiratory viral screen, including COVID-19 PCR, was negative. Parvovirus B19 / EBV / CMV: negative. Abdominal US showed splenomegaly. CT pulmonary angiogram excluded pulmonary embolism or pulmonary vasculitis. MRI spine excluded discitis. Bone marrow aspirate, performed after treatment, was normal. <strong>Differential &amp; Final Diagnosis: </strong>Initial diagnosis was infection. However, extensive cultures, screening and imaging did not reveal a source. Other diagnoses considered included vasculitis relapse or systemic lupus erythematosus (SLE) flare given lupoid features historically. The pattern of these features suggested possible SLE/AAV overlap or an underlying genetic immune-dysregulation. The final diagnosis was secondary haemophagocytic lymphohistiocytosis / macrophage activation synome (sHLH/MAS). This hyperinflammatory synome is characterised by fever, splenomegaly and cytopenia and is associated with hyperferritinaemia. HScore<sup>1</sup> was calculated at 257, equating to &gt;99% probability. <strong>Discussion of Management</strong>: Our patient received IV methylprednisolone (total 1.5g) and IV immunoglobulin (total 150g) over 3 days, followed by tapering prednisolone. Consideration was given to anakinra but was not required due to rapid response. She subsequently recommenced mycophenolate mofetil maintenance therapy chosen due to features of SLE. <strong>Conclusions: </strong>Here we report a case of a patient with atypical MPO-ANCA vasculitis complicated by sHLH/MAS. This association is rare and has been seldom reported in literature. Clinical similarities between infection and autoimmunity can lead to diagnostic delay preventing timely treatment in patients at risk of MAS. This case presents an additional diagnostic challenge with features suggestive of an autoinflammatory disorder suggesting SLE overlap and/or genetic immune dysregulation. <strong>Disclosures:</strong> None