Endocrine Abstracts

JOINT2409

Introduction: IgG4-related disease (IgG4-RD) is a multisystemic fibroinflammatory condition characterized by clinical, histological, and serological markers. It presents with organomegaly, histological lymphoplasmacytic infiltration with IgG4+ plasma cells, varying degrees of storiform fibrosis, and elevated serum IgG4 levels. Most patients have multi-organ involvement, including the orbit. In cases of atypical orbital changes, besides thyroid eye disease (TED), IgG4-related orbital disease (IgG4-ROD) should also be considered.

Case 1: A 38-year-old female presented with eyelid swelling and hyperemia, conjunctival chemosis, and proptosis of the right eye, along with ipsilateral cheek swelling. Orbital MRI revealed right-sided exophthalmos (OD 25 mm, OS 17 mm), enlargement of the medial and lateral rectus muscles, borderline enlargement of the inferior rectus, and increased retrobulbar fat. Thyroid hormone levels were normal, and TRAb levels varied between <0.8–1.9IU/l (ref.range: 0.0-1.8IU/l). Serum IgG4 was elevated(2.87g/l). Her medical history is remarkable for atopy, nasal polyps, bronchial asthma, and surgery of the left submandibular salivary gland due to its enlargement, with extraction of regional lymph nodes. Due to persistently elevated liver enzymes and ASMA positivity with hepatomegaly, a liver biopsy was performed, showing severe steatohepatitis(NAS 7/8) but no signs of IgG4-RD. A review of the histopathology of a previously resected submandibular gland and lymph nodes confirmed probably IgG4-RD. Case 2 A 43-year-old male presented with bilateral eyelid swelling, more pronounced on the right side, with an enlarged right lacrimal gland. Orbital CT revealed an enlarged right lacrimal gland and mild inflammation of the left lateral rectus muscle. His thyroid hormone levels were normal, TRAbs ranged from <0.8–2.4IU/l. Serum IgG4 was significantly elevated (6.09g/l). His medical history included bronchial asthma and nasal polyps. MRI with MRCP, performed due to abnormal liver function tests, revealed primary sclerosing cholangitis. Liver biopsy showed no histological characteristics of IgG4-RD.

Conclusion: Two patients were referred to our clinic with suspected TRAb-negative TED, but further investigations suggested IgG4-RD. Findings supporting IgG4-ROD included elevated serum IgG4, multi-organ involvement, and atypical orbitopathy (predominantly unilateral involvement, enlarged lateral rectus in both cases, and lacrimal gland involvement in the second patient). In the first case, histology of the salivary gland was used as a surrogate marker supporting IgG4-RD, increasing the likelihood that the ocular changes shared the same etiology. Features arguing against TED included normal thyroid function and morphology with negative to borderline elevated TRAbs, and the absence of a typical pattern of extraocular muscle involvement. TED and IgG4-ROD have overlapping orbital manifestations, making differential diagnosis challenging.