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Abstract Background/Aims IgG4-related disease (IgG4-RD) and granulomatous polyangiitis (GPA) have apparent different pathology. There are infrequent reports of the two conditions occurring simultaneously. We add to the literature by describing a patient who appears to have both conditions. Methods A 65-year-old male presented with low back pain radiating to the perineum. His past history included T2DM, CABG and ablation for AF. Initial investigations showed a CRP of 102mg/ml and an eGFR of 90ml/hr. A CT urogram revealed possible aortitis. A dedicated aortogram showed a cuff of added tissue around the infrarenal aorta and iliac arteries. A whole aortogram showed an increase in the abnormal tissue and detected a left upper lobe cavitating lesion. A PET-CT scan showed activity in the infrarenal aortic tissue, with focal uptake in the aortic arch and right superficial femoral artery. Several pleural based and parenchymal lesions showing moderate increased FDG activity were seen. A CT scan of the sinuses showed multifocal sinonasal mucosal thickening without bony erosions. C-ANCA was positive at 1/40, with raised PR3 of 32U/ml and IgG4 of 2.2g/L. Other immunoglobulin levels were normal and IGRA was negative. A biopsy of the lung lesion showed necrotising granulomatous inflammation and surrounding palisading histocytes, withno vasculitic element. Treatment with prednisolone 40mg daily and methotrexate 15mg weekly was started. A quick symptomatic improvement followed. CRP fell to 14mg/ml within two months. It was discussed in the national IgG4-RD MDT, and the consensus was that he had features of both GPA and IgG4-RD. A follow-up CT scan showed reduction in the volume of para-aortic tissue, with regression of some lesions in the chest, while others increased. However, he remains well with a normal CRP, stable renal function and normal urinalysis. His latest IgG4 level dropped to 0.67 g/L. Results The ANCA positivity and lung biopsy findings satisfy classification criteria of GPA. While aortic involvement is not commonly seen in GPA; it is typical of IgG4-RD; however, its diagnostic criteria require a confirmatory biopsy. This is challenging due to the risk of sampling around the aorta and ureters. Our case fulfils criteria for ‘possible’ IgG4-RD. In retrospect, an earlier PET CT scan may have spared the patient several CT scans. Conclusion The co-existence of IgG4-RD and ANCA-associated vasculitis may be more common than might be expected. Our case highlights the usefulness of early PET-CT scanning in rheumatic conditions. It is important to check ANCA in suspected IgG4-RD cases. It is possible that future AI programmes may help clinicians better judge the timing of investigations that may be more expensive, invasive or have increased radiation exposure in such complex cases. Finally, the usefulness of a national MDT for IgG4-RD is highlighted. Fortunately, treatment modalities are similar for both conditions. Disclosure H. Eltahir: None. M. Lloyd: None.
Eltahir et al. (Mon,) studied this question.