Anca-Associated but Not Vasculitis

ABSTRACT

Background/Aims A 72-year-old lady presented in primary care with complaints of generalised body aches, bilateral leg weakness and constitutional symptoms following a first dose of COVID-19 vaccine. Blood tests showed slightly raised inflammatory markers. She was initially diagnosed with polymyalgia rheumatica and was started on 40mg prednisolone with minimal improvement. Methods The examination in the rheumatology clinic was unremarkable. Investigations revealed raised white cell count, consistent with high dose steroid treatment, and elevated monocytes. There was mild improvement in inflammatory markers. The working diagnosis was of self-limiting viral illness. Further testing discovered strongly positive MPO ANCA (115 IU/ml), and the patient received three pulses of 500mg methylprednisolone for suspected vasculitis arranged by the medical team. There was no evidence of renal involvement. The diagnosis made at this point was autoimmune inflammatory disorder with unclear aetiology. At the subsequent clinic visit she reported mild shortness of breath, but no other symptoms suggestive of either vasculitis or connective tissue disease. Repeat ANCA showed significant reduction in MPO titre following pulse steroid treatment. CT of chest, abdomen and pelvis demonstrated a localised lobular/ nodular deformity of the liver. Viral hepatitis screen was negative. CA19-9 was raised at 100 U/ml. Liver biopsy was reported as poorly differentiated carcinoma without specific localising immunohistochemical features. Results The patient underwent hemi-hepatectomy for histologically confirmed pT2pNXM0R0 liver cholangiocarcinoma in a tertiary centre followed by adjuvant chemotherapy with capecitabine. With treatment, her MPO ANCA and CA19-9 levels declined. An interval CT scan of chest, abdomen and pelvis performed ten months after the surgery, showed no recurrence of malignancy. Given the fact that the patient's MPO ANCA fell following the treatment of cholangiocarcinoma, it is likely that positive MPO ANCA is associated with underlying malignancy rather than an active vasculitis. Conclusion This unusual case describes an evolution of the diagnostic process guided by non-specific symptoms and ANCA positivity, arriving at an unexpected diagnosis of malignancy. Although ANCA is a sensitive and specific marker of vasculitides, it can be positive in other conditions particularly hepatitis B, inflammatory bowel disease and autoimmune liver disorders. Malignancy can also be associated with ANCA in the absence of vasculitis. In one study, of 118 ANCA positive patients without ANCA-associated vasculitis, four were found to have malignancy. In a study of 1024 patients who had ANCA tested, 61 patients were found to have malignancy, predominantly haematological and lung cancers. However, after adjustment for sex, age and time of blood draw, no association was found between ANCA status and incidence of cancer. Interestingly, paraneoplastic vasculitis such as polyarteritis nodosa (PAN) has been described in the context of underlying cholangiocarcinoma, and is associated with ANCA rise. Moreover, patients with raised ANCA and PAN also have raised CA 19- 9.