Background/Purpose: Inflammatory aortitis is an uncommon condition that can be associated with rheumatologic, neoplastic, or infectious diseases. GCA and isolated aortitis are the most common causes. Although diagnosis is typically based on a combination of clinical, laboratory, and imaging findings—with PET-CT being a key tool in evaluating active inflammatory processes—it is often underdiagnosed prior to surgery, and the diagnosis of aortitis is frequently made only after pathological confirmation. Current literature includes few studies that specifically examine the relationship between preoperative PET-CT results and histopathological findings in patients with inflammatory aortitis.ObjectiveTo analyze the relationship between histopathological findings and preoperative PET-CT results in patients with biopsy-confirmed inflammatory aortitis or those under rheumatology follow-up.

Methods: Between 2020 and 2023, a total of 188 surgical procedures for aortic pathology were performed at our hospital. Cases were selected if they met at least one of the following criteria: (1) identification of an inflammatory pattern based on the standards of the Society for Cardiovascular Pathology and the Association for European Cardiovascular Pathology, or (2) active follow-up for a diagnosis of aortitis by the Rheumatology Department. A total of 37 cases met the inclusion criteria. From this cohort, we selected patients who had undergone PET-CT prior to surgery and tissue sampling.

Results: Five patients with a confirmed diagnosis were included: one with GCA, one with peripheral SpA, one with isolated aortitis, one with inflammatory atherosclerotic aneurysm, and one with infectious aortitis. Clinical and demographic characteristics are shown in Table 1. Two patients underwent emergency surgery for acute aortic syndrome. In one case, a PET-CT performed 4 months prior showed aortomegaly without inflammatory signs, and the biopsy confirmed a non-inflammatory degenerative process, despite elevated CRP at the time of both procedures. In the other case, PET-CT performed the day before surgery revealed an aortic aneurysm without signs of vasculitis, while histological analysis showed a lymphoplasmacytic inflammatory infiltrate with associated fibrosis; this patient also had elevated CRP levels. The remaining 3 patients underwent elective surgery for aortic aneurysm. In these cases, PET-CT also showed no signs of inflammation; however, histopathological analysis revealed inflammatory infiltrates in all specimens (Table 2 and Image). In summary, among the cases analyzed, concordance between PET-CT and histopathological findings was observed in only 1 of 5 patients. In 4 patients, PET-CT results were negative, while biopsies demonstrated characteristic inflammatory patterns.

Conclusion: In this sample, a weak correlation was observed between PET-CT findings and histopathology. Some patients with negative PET-CT scans, showing no evidence of increased metabolic activity, exhibited inflammatory patterns on histological analysis. These findings suggest that a significant proportion of patients with negative PET-CT results may still have an underlying vasculitic process.

Table 1. Clinical and Demographic Characteristics

Table 2. Correlation Between PET-CT Findings, Histology, and Rheumatologic Diagnosis

Histopathological sections corresponding to the patients in Table 2. (1) Non-inflammatory medial degeneration with diffuse extracellular mucinous matrix. (2) Lymphoplasmacytic infiltrate and stromal fibrosis in adventitia. (3) Severe calcified arteriosclerosis with chronic lymphoid infiltrate. (4) Non-necrotizing granulomatous inflammation with multinucleated giant cells. (5) Acute neutrophilic infiltrate with adventitial necrosis.

« Back to ACR Convergence 2025

ACR Meeting Abstracts - https://acrabstracts.org/abstract/correlation-between-histopathological-findings-and-pet-ct-results-in-patients-with-inflammatory-aortitis/