In this study, a significant difference was demonstrated in the clinical outcomes between patients undergoing biopsy and those undergoing debulking surgery for IgG4-ROD. The debulking surgery group exhibited reduced corticosteroid dependency and lower recurrence rates compared with the biopsy group. These findings are consistent with previous studies that report recurrence rates of 36–75% following corticosteroid therapy and 13% following debulking surgery [6,7,8, 15, 16, 18, 19]. The results of our study support these figures, with recurrence rates of 12.5% in the debulking group and 71.4% in the biopsy group being observed. The uniqueness of our study is its direct comparison of these two treatment methods within the same clinical environment, an aspect not previously explored in the literature.

One recurrent case after debulking surgery presented with eyelid swelling without a palpable mass in the lacrimal gland area. This observation indicates that while debulking surgery effectively reduces lacrimal gland mass, it does not entirely suppress inflammation in the eyelid tissue. Previous studies report that lacrimal gland enlargement occurs in 68–88% of IgG4-ROD cases, while eyelid swelling is observed in 12–21% of cases [2, 5, 20]. While debulking surgery alone may be sufficient for most cases primarily involving the lacrimal gland, patients presenting with prominent eyelid swelling, a less common symptom, might require additional management strategies, such as steroid administration. Further studies with larger cohorts and longer follow-up periods are needed to better understand the frequency and characteristics of swelling recurrence after debulking surgery, as well as the rate of new-onset eyelid swelling during follow-up.

In this study, we administered a standardized dose of 30 mg/day of prednisolone to all patients, irrespective of their body weight. While, based on existing literature this dosage falls within the recommended range of 0.5–1 mg/kg/day [7, 15, 16], it is important to acknowledge that, due to variations in body weight a fixed dose does not yield equal efficacy among all patients. For example, a 30 mg dose might be relatively high for a patient weighing 30 kg but insufficient for one weighing 80 kg. This variation in effective dosages potentially influences treatment outcomes, including the rate of relapse and the need for maintenance therapy.

Reports indicate that 40–56% of patients develop new-onset diabetes or worsening of diabetes after undergoing oral corticosteroid therapy [21, 22]. In the present study, one individual developed diabetes and another experienced a worsening of his condition. Although both these patients were in the biopsy group, complications of diabetes due to corticosteroids can arise in any patient. Thus, minimizing corticosteroid use aids in reducing such complications.

Mombaerts et al. describe in detail the efficacy and safety of debulking surgery for corticosteroid-resistant dacryoadenitis; their study was not limited to IgG4-related cases [23]. They found that 80% of patients did not experience disease recurrence after surgery, indicating the procedure’s effectiveness. However, the remaining 20% required additional interventions, such as orbital radiation or rituximab treatment. Although approximately half the patients experienced mild dry eyes as a side effect, the dry eyes were generally manageable with administration of eye drops. Thus, similar to the current study, the overall safety of debulking surgery was demonstrated.

A critical surgical consideration was preserving the palpebral lobe of the lacrimal gland. This approach is grounded in the anatomical and functional significance of the palpebral lobe, which is crucial for preventing postoperative severe dry eyes [14, 24]. Removal of the palpebral lobe can damage the penetrating secretory ducts of the orbital lobe, thus resulting in severe secretion deficiency. In contrast, removal of only the orbital lobe does not result in severe dry eyes because the remaining palpebral lobe works well, even though lacrimal secretion is, to some extent, reduced [25].

This study had several limitations. First, as a retrospective study with a limited patient sample, larger prospective studies are needed for definitive conclusions. Second, the different corticosteroid regimens between groups (routine in biopsy vs. only for relapse in debulking) complicate direct comparisons. Although the lower relapse rate in the debulking group suggests reduced corticosteroid need, this interpretation requires caution due to differing protocols and potential confounders. Third, corticosteroid administration may also be influenced by extraorbital manifestations of IgG4-RD like single case with concurrent sphenoid lesion in debulking group, potentially leading to misinterpretation of treatment effects in the lacrimal gland lesion. In either group, no new extraorbital lesions affecting corticosteroid therapy were identified during the follow-up period, although whole-body CT scans were not performed to avoid unnecessary radiation exposure. Fourth, relapse was defined by subjective findings, as postoperative imaging was not routinely performed to avoid invasiveness. Lastly, mean follow-up periods differed significantly between groups due to timing-dependent decisions of surgical strategies.

In summary, our findings indicate that debulking surgery is a viable and effective method for managing IgG4-ROD, potentially lowering recurrence and dependence on corticosteroids. Moreover, this study highlights the importance of employing the correct surgical techniques to effectively control the risk of postoperative dry eyes.