PO:28:116 | Glandular involvement in autoimmune diseases: a spectrum of differential diagnosis

Francesca Petrillo¹, Caterina Ricordi¹, Caterina Tomassini¹, Luca Cimino³, Giorgia Citriniti², Fabio Brandolino², Chiara Marvisi¹, Carlo Salvarani¹ | ¹S.C. Reumatologia; ²S.C. Reumatologia; ³S.S.D. Immunologia Oculare, Università di Modena e Reggio Emilia, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy

Background. Sarcoidosis is a multisystem disease of unknown etiology, characterized by the presence of non-necrotizing granulomas in multiple organs. It is a clinical condition capable of mimicking several disorders. For an accurate differential diagnosis, histopathological examination of the affected organ is crucial, in addition to clinical, radiological, and laboratory findings.

Case Report. We report the case of a patient with a suspected IgG4-related disease in a differential diagnosis of sarcoidosis. A 25-year-old Pakistani male, smoker, and stable worker was referred to rheumatologic evaluation in January 2025 for progressive, painless, bilateral periorbital and parotid swelling that had developed since November 2024. Ophthalmologic examination and subsequent orbital MRI confirmed the presence of bilateral glandular hypertrophy. The patient denied any infectious episodes preceding symptom onset. His past medical history included only a left-sided Bell’s palsy with lagophthalmos in 2021, occurring after the first dose of the SARS-CoV-2 vaccine, which resolved after a short course of corticosteroids. At the presentation, he denied dry cough, dyspnea, fever or low-grade fever, arthritis/arthralgia, visual impairment, erythema nodosum, cutaneous lesions, or gastrointestinal symptoms. Physical examination revealed painless swelling of the parotid, submandibular, and lacrimal glands, associated with conjunctival hyperemia and lagophthalmos. Palpable, non-tender, mobile lymph nodes were noted in the right retroauricular and left laterocervical regions; no joint inflammation was detected. Given the suspicion of an IgG4-related disease, hospital admission was planned. During hospitalization, the patient underwent • Laboratory tests: ESR 45 mm/h, CRP 0.5 mg/dL, ACE 66 U/L, severe vitamin D deficiency (<4 ng/mL), PTH 36.3 pg/mL; normal serum calcium, phosphate, and 24-hour urinary calcium (145.2 mg). The patient's IgG subclasses were within normal limits, and both autoimmune and infectious serologies were negative. • Whole-body FDG-PET: Increased radiotracer uptake in bilateral parotid glands, bilateral hilar and peribronchovascular regions, and ocular bulbs. • Abdominal ultrasound: Unremarkable. • Ocular immunology evaluation: There were no signs of granulomatous uveitis. Empirical treatment with oral prednisone (50 mg daily) was initiated. Subsequently, a biopsy of the left parotid gland was performed, showing a fibroinflammatory process with granulomas containing small necrotic foci, consistent with sarcoidosis. Chest CT revealed multiple peribronchovascular pulmonary nodules and hilar-mediastinal lymphadenopathy. A diagnosis of sarcoidosis involving the lacrimal and parotid glands, lymph nodes, and pulmonary parenchyma (Stage II) was therefore established. Corticosteroid therapy (prednisone 0.5 mg/kg/day) was maintained, and methotrexate 20 mg weekly was added as a steroid-sparing agent. At follow-up in March 2025, a marked clinical improvement was observed, with significant reduction of parotid and lacrimal gland swelling. This case highlights the importance of an appropriate differential diagnosis among granulomatous diseases and the pivotal role of histopathological confirmation in establishing a definitive diagnosis.