PO:11:172 | Not all vasculitis look the same: a difficult diagnosis

Marta Arese^1|2, Miriam Perino^1|2, Sofia Aliprandi^1|2, Antonella Murgo², Maria Gerosa^1|2, Roberto Felice Caporali^1|2 | ¹UOC Reumatologia AOR San Carlo, Potenza; ²Reumatologia Clinica, ASST Gaetano Pini-CTO, Milano, Italy

Background. Vasculitides represent a heterogeneous group of systemic inflammatory diseases, often difficult to classify and requiring multidisciplinary management.

Case Report. We present the case of a 68-year-old woman with a thoracic aortic aneurysm and a history of recurrent episodes of pneumonia with pleuritis. Since March 2024, she reported worsening pruritus (with a history of contact dermatitis) and alopecia. Starting in October, low-grade fever (T max 38°C), exertional dyspnea, and weight loss appeared. Chest CT scan showed bronchiolar wall thickening with fibrotic-disventilatory strands and an aortic aneurysm (53–55 mm). Admitted to cardiac surgery, on 14/03/2025, she underwent replacement of the ascending aorta with a Dacron valved conduit and aortic valve repair/plasty. Histological examination documented a marked lymphomonocytic infiltrate with tertiary germinal centers in the intima, involvement of the vasa vasorum, mucinoid degeneration, neoangiogenesis of the tunica media, and adventitial thickening with hyalinosis, consistent with giant cell aortitis , even in the absence of granulomas and macrophages and skip lesions. From May 5 to 23, she was admitted to our Rheumatology department for diagnostic work-up. Color Doppler ultrasound of the carotid and vertebral arteries, temporal arteries, renal arteries, and aortic axis was normal. FDG-PET scan showed vascular uptake solely in the ascending aorta, and multiple pulmonary accumulations (right lower lobe, parascissural regions, apices, hilar/paratracheal lymph nodes). HRCT revealed vague peribronchial consolidations suggestive of inflammation. Serology was negative for active infections (Quantiferon, EBV, CMV, HIV, Toxoplasma, Treponema pallidum); ANCA, ENA, RF, IgG4, anti-DNA, and liver autoantibodies were negative. ACPA was weakly positive; Lupus Anticoagulant (LAC) and IgG anticardiolipin antibodies were positive, leading to the initiation of anticoagulation therapy with warfarin (INR target 2.5). ESR 62 mm/h, CRP 9 mg/dL, eosinophils 780 mm³. Blood cultures were negative. Starting on May 13, therapy was initiated with prednisone 25 mg daily at a reduced dosage due to suspected infection, and a reduction in inflammation was observed (ESR 44 mm, CRP 0.09 mg/dL). BAL (bronchoalveolar lavage) for atypical mycobacteria investigation was proposed and is ongoing. A diagnosis of giant cell aortitis with pulmonary involvement (micronodules and tree-in-bud pattern) was made. Excluded diagnosis: Syphilis (negative serology and histology), tuberculous vasculitis (absence of granulomas, dissemination, reactive lymph nodes on PET, CT, and lymph node ultrasound, negative Quantiferon), EGPA (absence of asthma/rhinitis, fixed pulmonary infiltrates, negative ANCA), SLE (initially suspected due to alopecia, dermatitis, and ANA+, but excluded by a dermatologist who diagnosed eczematous atopic dermatitis and alopecia areata).