Fig. 14

35-year-old female patient with painful proptosis, loss of vision, and subcutaneous facial swelling. Biopsy of the face performed in an outside institution suggested inflammatory pseudotumour. a. Coronal STIR image shows an ill-defined, moderately hyperintense lesion involving the entire left orbit (asterisk) and encasing the optic nerve (thin arrow). The subcutaneous hyperintense, poorly defined area on the left (hollow arrow) corresponds to the biopsied region. b. Axial contrast-enhanced FS T1W MR image of the same patient as in a. The left orbital lesion shows diffuse post-contrast enhancement (asterisk). Enhancing soft tissue is seen extending along the left superior orbital fissure into the left cavernous sinus (arrow) and the dura along the left greater wing of sphenoid. c. Axial contrast-enhanced FS T1W image at the level of the maxillary sinus demonstrates perineural spread along the pterygopalatine fossa and maxillary nerve (arrows). Hollow arrows in b and c point at extra-orbital involement. d. ADC map reveals restricted diffusion of the orbital lesion with very low ADC values (ADC = 0.7 × 10 ⁻³ mm²/s) suggesting lymphoma. The optic nerve shows even lower ADC values (thin arrows) due to compression and ischemia. e. Colour coded DTI map shows major reduction of FA values in the left optic nerve (thin arrows). FA values were 0.4–0.5 on the left and 0.56–0.58 on the right. f. FDG PET/CT demonstrates high tracer uptake in the orbit (asterisk), along the superior orbital fissure and in the cavernous sinus and sphenoid (arrows) confirming findings revealed in b. SUVmean = 10, max = 16. Other hypermetabolic lesions were found in the neck nodes, mediastinum, and abdomen. Biopsy of orbital contents revealed NHL