Oral abstract presentation times

Purpose

Prebiopsy distinction between malignant lymphoproliferative and inflammatory orbital lesions is challenging. Although MRI and diffusion-weighted imaging have shown diagnostic value in selected research settings, their performance in routine prebiopsy clinical practice remains uncertain. We compared clinical and radiologic features of these lesions and assessed the real-world triage performance of routine MRI, including DWI.

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Methods

In this retrospective single-center study, 177 biopsied orbital lesions, including 94 malignant lymphoproliferative and 83 inflammatory lesions, were analyzed. Routine radiologic interpretations were classified as benign, malignant, or indeterminate. Diagnostic performance was assessed. In an exploratory subanalysis, apparent diffusion coefficient values were retrospectively measured from ADC maps.

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Results

Malignant lymphoproliferative lesions were associated with older age, intraconal involvement, eyelid involvement, and prior oncologic history, whereas pain and lacrimal gland involvement were more frequent in inflammatory lesions. 23.5% of cases were radiologically indeterminate. Radiologic accuracy was 70.2%, sensitivity 74.1%, and specificity 65.2%. DWI increased sensitivity from 53.3% to 81.6%. ADC values were significantly lower in malignant lymphoproliferative than in inflammatory lesions, with median values of 0.646 versus 1.16 × 10⁻³ mm²/s, respectively (p < 0.001). In exploratory ROC analysis, ADC showed strong discriminatory performance (AUC 0.936).

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Conclusion

Routine MRI provides useful but imperfect prebiopsy triage information for distinguishing malignant lymphoproliferative from inflammatory orbital lesions, with a relevant proportion of indeterminate interpretations. DWI improves sensitivity, and exploratory ADC analysis supports diffusion restriction as a valuable adjunctive marker. Integrated clinical-radiologic assessment may help prioritize biopsy urgency, particularly by identifying patients with high malignancy concern or functional threat who may require expedited tissue diagnosis.

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Additional Authors

First name	Last name	Base Hospital / Institution
Reem	Alshammari	Charité Universitätsmedizin Berlin
Katharina	Erb-Eigner	Charité Universitätsmedizin Berlin
Eckart	Bertelmann	Charité Universitätsmedizin Berlin

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