Immunoglobulin G4-related disease (IgG4-RD) was not recognised as a systemic condition until 2003, when extra pancreatic manifestations were identified in patients with autoimmune pancreatitis. Since then, IgG4-RD has been described to involve virtually every organ system. It is highly responsive to immunosuppressants but can have detrimental effects if left untreated. Early recognition of the disease is, therefore, critical. The diagnosis of IgG4-RD is frequently challenging owing to its non-specific clinical manifestations, indolent nature and broad differential diagnoses. Although histopathological examination remains the cornerstone of diagnosis, imaging plays an important role in establishing extent of disease and identifying areas suitable for biopsy. ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) has been demonstrated to be useful in assessing organ involvement, guiding biopsy and monitoring disease response. The ¹⁸F-FDG PET/CT scan is highly sensitive and able to evaluate multiorgan involvement in a single examination, a key advantage over conventional imaging modalities. A potential pitfall is its low specificity. As such, detailed knowledge of the imaging findings in IgG4-related disease is required to avoid misdiagnosis. This pictorial review aims to depict the diverse spectrum of imaging findings of IgG4-RD and the key imaging features to distinguish it from other important differential diagnoses.

The widespread use of neck US and other imaging modalities has contributed to a phenomenon of increased detection of differentiated thyroid cancer (DTC). Most of these cancers remain indolent, without requiring surgical intervention. Nonetheless, a subset of patients who require surgical treatment experience subsequent disease recurrence. This most commonly occurs in the cervical lymph nodes and thyroid bed, followed by distant metastasis to the lungs and bones. Because imaging is an integral part of postoperative surveillance, radiologists play a central role in the detection of recurrent tumors and in guiding treatment in these patients. US is the primary imaging modality used for postoperative evaluation. Other modalities such as CT, MRI, radioactive iodine imaging, and PET/CT aid in the accurate diagnosis and characterization of recurrent disease. Therefore, radiologists must have a thorough understanding of the utility of these imaging techniques and the imaging characteristics of recurrent DTC when interpreting these multimodality studies. The interpretation of imaging findings should also be correlated with the clinical status of patients and their biochemical markers to minimize interpretative errors. The authors present a broad overview of the postoperative evaluation of DTC, including its initial primary management, staging, and prognostication; clinical risk stratification for recurrent disease; postoperative surveillance with imaging and evaluation of biochemical markers; and management of recurrent DTC. Published under a CC BY 4.0 license. Supplemental material is available for this article.

Recent data suggest that protective immunity from COVID-19 vaccine may wane after a period, with booster doses becoming increasingly deployed in many countries. An 84-year-old woman presents with a 6-month history of left upper-limb swelling; the only history of note was an intramuscular Pfizer-BioNTech mRNA vaccine booster in the ipsilateral deltoid just 1 week before the onset of the swelling. Upper-extremity lymphoscintigraphy after the administration of ^99mTc-nanocolloid into the interstitial space of the hands showed left upper-limb lymphatic dysfunction.

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