The role of PET/CT in thyroid autoimmune diseases.

Autoimmune thyroid diseases (AITD) are a heterogeneous group of disorders. They include, in particular, Graves' disease and Hashimoto's thyroiditis with a wide range of different functional status ranging from subclinical biochemical abnormalities to severe hyperthyroidism or severe hypothyroidism respectively. Furthermore, other conditions more frequently infectious or drug related can cause an immune reaction in the thyroid tissue. In AITDs, positron emission tomography/computed tomography (PET/CT) does not play a primary role for disease diagnosis or management, but accidental findings can occur in both symptomatic and asymptomatic patients, and they should be recognized and well interpreted. A comprehensive literature search of the PubMed databases was conducted to identify papers (systematic review, prospective and retrospective study, case report) evaluating the role of PET/CT in thyroid autoimmune diseases. Thyroid diffuse uptake of 18F-fluoro-2-deoxy-2-d-glucose ([18F]FDG) has been shown to be frequently associated with AITDs, but also with immune-induced thyroid disorders related to SARS-CoV-2 or immunotherapy, while malignant lesions more often have a focal aspect. Other radiopharmaceuticals as [68Ga]-DOTA-peptides, [68Ga]-fibroblast activation protein inhibitors (FAPIs) and [68Ga]-prostate specific membrane antigen ([68Ga]-PSMA) showed similar findings. In conclusion, PET/CT scan in AITDs does not play a primary role in the diagnosis, but the occasional finding of a thyroid uptake must always be described in the report and possibly investigated for a better patient's management.

A case of type 2 autoimmune pancreatitis with spontaneous remission.

A 70-year-old man with epigastric pain was referred to our hospital. Computed tomography and magnetic resonance imaging showed the diffusely enlarged pancreas compared to his normal pancreas 6 months prior to presentation. Serum levels of IgG4 and amylase were normal, while C-reactive protein was slightly elevated. Endoscopic ultrasound-guided fine-needle biopsy of the pancreas revealed acinar-ductal metaplasia with neutrophil infiltration and without infiltration of IgG4-positive plasma cells. After the clinical diagnosis of type 2 autoimmune pancreatitis (AIP), his symptoms spontaneously improved without steroid therapy. Three months later, radiological findings showed improved pancreas size and serological findings. The pathological diagnosis of type 2 AIP using endoscopic ultrasound-guided fine-needle biopsy is challenging, particularly for proving granulocyte epithelial lesions. This was a valuable type 2 AIP case in which the images before, at the time of onset, and at the time of spontaneous remission were evaluated.

IgG4-Related Disease: A Constellation of Abdominal Manifestations.

IgG4-related disease is an autoimmune condition that results in inflammation and fibrosis throughout multiple organ systems. This disease is rare; however, it can mimic many more prevalent conditions clinically and thus should be included in their differential diagnoses. Although autoimmune pancreatitis is the most common abdominal manifestation, the disease can afflict the hepatobiliary, vascular and renal systems as well. We present a case of a 78-year-old male with symptoms of chronic fatigue and weight loss. Imaging was performed with the expectation of revealing a malignancy, although the features of IgG4-related disease involving multiple organs were detected instead. Serology confirmed the diagnosis. It is imperative to diagnose IgG4-related disease early as it has a different treatment and favorable prognosis compared to many malignancies.

Coronavirus disease 2019 (COVID-19) in patients with systemic autoimmune diseases or vasculitis: radiologic presentation.

Coronavirus disease 2019 (COVID-19) has transformed into a worldwide challenge, since its outbreak in December 2019. Generally, patients with underlying medical conditions are at a higher risk of complications and fatality of pneumonias. Whether patients with systemic autoimmune diseases or vasculitides, are at increased risk for serious complications associated with COVID-19, is not established yet. Computed tomography (CT) has been employed as a diagnostic tool in the evaluation of patients with clinical suspicion of severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection with a reported sensitivity of higher than reverse transcription polymerase chain reaction (RT-PCR) test. Multifocal bilateral ground-glass opacities (GGOs) with peripheral and posterior distribution and subsequent superimposition of consolidations are considered the main imaging features of the disease in chest CT. However, chest CT images of underlying rheumatologic or autoimmune diseases or vasculitides, such as systemic sclerosis, systemic lupus erythematosus, rheumatoid arthritis, Behçet disease, and granulomatosis with polyangiitis, especially those with extensive lung involvement can overshadow or obliterate features of COVID-19. In addition, CT findings of such diseases may resemble manifestations of COVID-19 (such as ground glass opacities with or without superimposed consolidation), making the diagnosis of viral infections, more challenging on imaging. Comparing the imaging findings with prior studies (if available) for any interval change is the most helpful approach. Otherwise, the diagnosis of COVID-19 in such patients must be cautiously made according to the clinical context and laboratory results, considering a very high clinical index of suspicion on imaging.