Fig. 1.

CT, small bowel series, and histologic findings in 43-year-old man with IgG4-related sclerosing disease of small bowel.

Contrast-enhanced axial (A) and coronal-reformatted (B) CT images show irregular thickening, loss of mural stratification and heterogeneous enhancement of distal ileal wall (arrows). Lesion also reveals aneurysmal dilatation. Another coronal-reformatted CT image (C) shows adhesion and aggregation of few small bowel loops (arrow). Another axial CT image (D) reveals multiple enlarged lymph nodes (arrowheads). Small bowel series (E) shows aggregation of distal ileum with traction, angulation and abrupt narrowing which indicates adhesion of ileal loops (arrows). Aneurysmal dilatation of involved segment is also noted (open arrow). On gross specimen (F) obtained from segmental bowel resection, resected ileum shows depressed lesion (4 × 3 cm) with thickened and edematous wall, forming interloop adhesion. On microscopic examination (G-I), ill-demarcated fibrotic lesion involving submucosa, muscle layer and serosa is seen with prominent lymphoplasmacytic infiltrate (G, Hematoxylin & Eosin, × 10). Lymphoplasmacytic infiltrates occasionally show germinal centers (H) and obliterative phlebitis is present (I). Immunohistochemical stain (J) reveals many IgG4-positive plasma cells (more than 50/high power field).