Yamada et al. Journal of Medical Case Reports 2012, 6:104 http://www.jmedicalcasereports.com/content/6/1/104 Page 3 of 4 Figure 3 Magnetic resonance imaging after steroid pulse therapy. High-intensity areas in the left caudate head, bilateral semicentral ovales, and bilateral occipital forceps majors are clearly enlarged on FLAIR and T2W imaging. Gd-enhanced lesions in the occipital forceps majors are clearly expanded. Figure 5 MRI after one month of steroid therapy. High-intensity areas in (FLAIR) and T2W imaging considerably shrink and Gd- enhanced lesions completely disappear after one month of steroid treatment. Arrows show the point of biopsy. Figure 4 Definite diagnosis of tMS by histological investigations. Histology shows proliferation of lymphocytes (arrowheads) without atypical features by hematoxylin-eosin (HE) staining (a). Kluver-Barrera staining demonstrates sporadic defects of myelin (arrows), indicating demyelinations (b). Perivascular lymphocyte proliferation is recognized by HE staining (c). These lymphocytes are composed mainly of CD3- positive T-cell lymphocytes (d), and a mixture of CD4-positive (e) and CD8-positive (f) T-cell lymphocytes rules out monoclonal increase of the lymphocytes. The appearance of macrophages (CD68) in the lesion strongly suggests inflammatory disease (g) rather than malignant lymphoma. CD: cluster of differentiation.