Evaluation of Orbital Lymphoproliferative and Inflammatory Disorders by Gene Expression Analysis

Non-specific orbital inflammation (NSOI) and IgG4-related orbital disease (IgG4-ROD) are often challenging to differentiate. Furthermore, it is still uncertain how chronic inflammation, such as IgG4-ROD, can lead to mucosa-associated lymphoid tissue (MALT) lymphoma. Therefore, we aimed to evaluate the diagnostic value of gene expression analysis to differentiate orbital autoimmune diseases and elucidate genetic overlaps. First, we established a database of NSOI, relapsing NSOI, IgG4-ROD and MALT lymphoma patients of our orbital center (2000−2019). In a consensus process, three typical patients of the above mentioned three groups (mean age 56.4 ± 17 years) at similar locations were selected. Afterwards, RNA was isolated using the RNeasy FFPE kit (Qiagen) from archived paraffin-embedded tissues. The RNA of these 12 patients were then subjected to gene expression analysis (NanoString nCounter®), including a total of 1364 target genes. The most significantly upregulated and downregulated genes were used for a machine learning algorithm to distinguish entities. This was possible with a high probability (p < 0.0001). Interestingly, gene expression patterns showed a characteristic overlap of lymphoma with IgG4-ROD and NSOI. In contrast, IgG4-ROD shared only altered expression of one gene regarding NSOI. To validate our potential biomarker genes, we isolated the RNA of a further 48 patients (24 NSOI, 11 IgG4-ROD, 13 lymphoma patients). Then, gene expression pattern analysis of the 35 identified target genes was performed using a custom-designed CodeSet to assess the prediction accuracy of the multi-parameter scoring algorithms. They showed high accuracy and good performance (AUC ROC: IgG4-ROD 0.81, MALT 0.82, NSOI 0.67). To conclude, genetic expression analysis has the potential for faster and more secure differentiation between NSOI and IgG4-ROD. MALT-lymphoma and IgG4-ROD showed more genetic similarities, which points towards progression to lymphoma.

The Role of Radiotherapy in Orbital Pseudotumor: A Systematic Review of Literature

PURPOSE

Orbital pseudotumor (or pseudotumor orbitae) is a benign entity, also known as idiopathic orbital inflammatory syndrome (IOIS), which encompasses a wide range of non-tumoral, space occupying lesions of the orbit. In selected cases of refractory disease or presence of side effects or even comorbidities that limit systemic therapies, radiotherapy could play a role in the management because it has been demonstrated that irradiation is effective in suppressing the inflammatory process.

METHODS

A systematic review of the literature about the main scientific databases was launched and the time interval included all published articles present in the databases from their inception until September 2020.

RESULTS

We were able to identify 19 studies eligible for inclusion in this review from 1978 to 2018. Overall the data of 241 patients were collected and are presented in this systematic review. The response rate varied between 74% and 100% with a median recurrence rate of 10%. The median total dose was 20 Gy whereas the mean total dose was 21 Gy with a range from 4 to 36 Gy. Regarding the fractionation, 2 Gy/fraction daily was the most widely used.

CONCLUSIONS

Radiotherapy seemed to achieve good response rates however, in most of the studies, inclusion criteria and outcome parameters are not uniform and therefore the results are difficult to compare. Often important parameters such as chronic pain and permanent functional deficits are not assessed in the outcome. Therefore, prospective studies, with good cohort characteristics and a clear definition of the outcome, are required.