Fig 1.

Orbital lymphoma (MALT lymphoma) in a 79-year-old woman. A, Transverse fat-saturated T2-weighted image; B, Transverse postcontrast fat-saturated T1-weighted image; C, Transverse DWI; D, ADC map; and E, Hematoxylin and eosin (HE)-stained biopsied specimen of the orbital tumor at low power field. An infiltrative mass involves the left lacrimal gland and extraocular muscles, appears isointense compared with the brain cortex on a fat-saturated T2-weighted MR image (A), and shows homogeneous contrast enhancement, similar to that of the right extraocular muscle (arrow) (B). The mass appears as strongly hyperintense on DWI (C) and hypointense on the ADC map (D). Notably, noninvolved extraocular muscles do not show hyperintensity similar to that of the mass on DWI (C). Lesion ADC and CER were 0.56 × 10⁻³ mm²/s and 1.69, respectively. HE-stained biopsied specimen (E) demonstrated numerous small-to-medium-sized atypical lymphocytes around reactive lymph follicles, with greater high cellular attenuation, however, interstitial fibrosis or edematous change was not prominent.