The branchial arches are the embryological precursors of the face, neck and pharynx. Anomalies of the branchial arches are the second most common congenital lesions of the head and neck in children, with second branchial arch anomalies by far the most common. Clinically, these congenital anomalies may present as cysts, sinus tracts, fistulae or cartilaginous remnants with typical clinical and radiological findings. We review the normal embryological development of the branchial arches and the anatomical structures of the head and neck that derive from each arch. The typical clinical and radiological appearances of both common and uncommon branchial arch abnormalities are discussed with an emphasis on branchial cleft anomalies.Key points• Anomalies of the branchial arches usually present as cysts, sinuses or fistulae.• Second branchial arch anomalies account for approximately 95 % of cases.• There are no pathognomonic imaging features so diagnosis depends on a high index of suspicion and knowledge of typical locations.• Persistent cysts, fistulae or recurrent localised infection may be due to branchial arch anomalies.• Surgical excision of the cyst or tract is the most common curative option.

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Translational RelevanceThere is an urgent need for progress in the management of breast cancer leptomeningeal metastasis (BCLM). Current diagnostics are hampered by impaired sensitivity, delaying diagnosis and treatment initiation. Further, during BCLM therapy there are no quantitative response markers to guide clinical decision making. This proof-of-concept study explored the use of ulpWGS, a methodology requiring no upfront knowledge of tumor mutations, to detect ctDNA in cerebrospinal fluid (CSF) in BCLM. ctDNA was detectable in all BCLM+ patients by ulpWGS, despite frequent negative CSF cytology. Importantly, CSF ctDNA was not detected in BCLM-free patients, supporting the potential for ulpWGS as a tool to refute diagnosis. In addition, CSF ctDNA reduction, measured by ulpWGS, was associated with improved survival on intrathecal BCLM treatment. This study highlights the potential of ulpWGSassessed CSF ctDNA fraction to improve BCLM care through timely diagnosis and adaptation of therapy, and warrants larger prospective studies to test clinical validity.

Lobar torsion is an uncommon phenomenon but a crucial diagnosis to consider in any patient undergoing lobectomy, as the clinical findings and radiographic appearances are non-specific. This case report documents the clinical and radiological evolution of middle lobe torsion in a patient who underwent right upper lobectomy for Stage 1 adenocarcinoma of the lung. The diagnosis of lobar torsion is most often made on CT scanning of the chest, which is frequently performed in order to distinguish this from multiple other more frequently encountered post-operative complications. Contrast-enhanced CT scan is the recommended imaging modality in suspected cases. If features of lobar torsion are identified, the findings must be communicated immediately to cardiothoracic surgeons owing to the potentially life-threatening consequences of delay. Management of lobar torsion is predominantly surgical, with several techniques currently in use; however, video-assisted thoracoscopic surgery is emerging as an increasingly favoured approach.