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A 70-year-old woman, previously treated with triple-inhalation therapy for bronchial asthma, presented to an ophthalmologist with diplopia. She had no history of smoking. MRI revealed an enlarged infraorbital nerve and nodular lesions in the lacrimal gland. Serum IgG4 levels were markedly elevated at 2158 mg/dL. Whole-body CT demonstrated thickened tracheal and bronchial walls, accompanied by multiple localised nodules in both bronchi ( figure 1a,b). In addition, swelling of bilateral submandibular glands and pancreatic enlargement were observed. 18F-fluorodeoxyglucose positron emission tomography CT showed increased fluorodeoxyglucose uptake in the enlarged lesions, including the bronchial walls (figure 1c). White-light bronchoscopy (1T260, Olympus) revealed diffuse oedematous narrowing of the trachea and segmental bronchi, with numerous localised elevated nodules (figure 1d–f). Transbronchial biopsy (TBB) was performed using 1.9 mm forceps (FB-231-D, Olympus), and cryobiopsy was concomitantly performed using a 1.7 mm cryoprobe (20 402–410, Erbe Elektromedizin GmbH) targeting elevated nodular lesions. TBB specimens were small and exhibited significant crush artefacts, hindering assessment of inflammatory cell infiltrates (figure 2a, right). In contrast, cryobiopsy specimens were larger, with minimal crush artefacts, and demonstrated subepithelial infiltration of plasma cells and lymphocytes, along with fibrotic foci (figure 2a, left). Over 100 IgG4-positive plasma cells per high-power field (HPF) were identified, with an IgG4/IgG ratio of 85% (figure 2b–d). However, obliterative phlebitis and storiform fibrosis were not observed in cryobiopsy specimens. Endoscopic ultrasound-guided fine needle aspiration (FNA) (GF-UCT260, Olympus) of the pancreas was performed using a 22G needle (Aquire, Boston Scientific). The FNA specimens demonstrated infiltration by plasma cells and lymphocytes, as well as fibrotic foci with obliterative phlebitis. Over 100 IgG4-positive plasma cells per HPF were observed, with an IgG4/IgG ratio of at least 40%. Storiform fibrosis was absent in the FNA specimens. Based on the 2019 American College of Rheumatology/European League Against Rheumatism classification criteria for IgG4-related disease (IgG4RD), the patient scored 49 points, meeting the diagnostic threshold for IgG4RD.1 Treatment with prednisolone (0.6 mg/kg) resulted in improved diplopia and resolution of all enlarged lesions, including bronchial involvement (figure 1g–i).