Retro-orbital and retroperitoneal disease in patient 1. (A) Before interferon-α, extensive retrobulbar soft tissue mass (arrows) is seen on the T1-weighted magnetic resonance imaging before (left) and after (right) gadolinium injection. (B) After 4 years of continuous interferon-α treatment, the extent of retrobulbar infiltration (arrows) continues to decrease substantially. (Ci) Perinephric adipose tissue reveals large foamy lipid-laden histiocytes with eosinophilic cytoplasm; (ii) staining positive for CD68, (iii) but staining negative for CD1a; and (iv) staining negative for S100 (< 5% positive). Images were acquired at a magnification of 200 × using a Nikon Microphot-FXA microscope (Nikon, Tokyo, Japan) fitted with a 20 × phase-contrast objective lens (PlanApo 20 ×/0.75 NA). Images were captured with a digital camera, model DP-70 (Olympus, Tokyo, Japan), using DP 12 image-acquisition software (Olympus), DP-70 (Olympus, Tokyo, Japan), using DP 12 image-acquisition software (Olympus), and image-processing was carried out using Microsoft PowerPoint (Microsoft, Redmond, WA).