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IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder characterised by IgG4-positive plasma cell infiltration into different tissues and organs. Among the heterogeneous clinical features of IgG4-RD, serositis, including pleural and pericardial effusions, is a rare and poorly understood presentation. We described a woman in her late 70s who developed recurrent chylothorax and failed to respond to corticosteroids, immunosuppressives and intrapleural octreotide injection while being treated for newly diagnosed IgG4-RD with serositis as the only manifestation. Her chylothorax was thought to be due to fibroinflammatory damage of the lymphatic duct system from her IgG4-RD, as other differential diagnoses have been largely excluded. We demonstrate the difficulty in establishing the diagnosis of IgG4-RD when only serositis is present, the importance of meticulous workup ruling out other causes and clinical judgement in identifying disease complications versus evaluating alternative diagnoses., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2025. No commercial re-use. See rights and permissions. Published by BMJ Group.)

The somato-cognitive action network (SCAN) consists of three nodes interspersed within Penfield's motor effector regions. The configuration of the somato-cognitive action network nodes resembles the one of the 'plis de passage' of the central sulcus: small gyri bridging the precentral and postcentral gyri. Thus, we hypothesize that these may provide a structural substrate of the somato-cognitive action network. Here, using microdissections of sixteen human hemispheres, we consistently identified a chain of three distinct plis de passage with increased underlying white matter, in locations analogous to the somato-cognitive action network nodes. We mapped localizations of plis de passage into standard stereotactic space to seed fMRI connectivity across 9,000 resting-state fMRI scans, which demonstrated the connectivity of these sites with the somato-cognitive action network. Intraoperative recordings during direct electrical central sulcus stimulation further identified inter-effector regions corresponding to plis de passage locations. This work provides a critical step towards improved understanding of the somato-cognitive action network in both structural and functional terms. Further, our work has the potential to guide the development of refined motor cortex stimulation techniques for treating brain disorders, and operative resective techniques for complex surgery of the motor cortex., (© The Author(s) 2025. Published by Oxford University Press on behalf of the Guarantors of Brain.)