PMC4720812_01
Immunoglobulin G4-related disease in 51-year-old man.. A. Axial contrast-enhanced CT image shows 3.6 cm solid mass at appendiceal tip (arrows). Associated periappendiceal fat infiltrations suggest that mass is inflammatory. B. Axial contrast-enhanced CT taken 21 days after initial CT (A). No significant change in mass is noted. However, periappendiceal fat haziness is aggravated (arrows). C. Right hemicolectomy includes 29 cm of ascending colon and 21 cm of ileum. Appendix forms mass sized 4.3 x 2.8 x 1.7 cm with fat proliferations on surface (arrow). D. Hematoxylin-eosin staining shows plasmacytic infiltration in subserosa of appendix (black arrows). Mucosal layer and muscle layer of appendix (white arrows) are intact suggesting that main pathology lies in mesentery rather than appendix (x 12.5). E. Immunoglobulin G4 (IgG4) stain shows IgG4-positive plasmacytes. Brown pigmented cells (arrows) are IgG4-positive cells. On IgG staining, > 50% of IgG-positive cells are IgG4 positive (not presented) (x 400).
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F1
Accompanying perimesenteric fat haziness suggested that the mass could be inflammatory (Fig. 1A), but malignancy could not entirely be ruled out. The second CT scan did not show a significant change in the solid mass at the appendiceal tip, but the periappendiceal mesenteric fat haziness was aggravated (Fig. 1B). Resected appendix measured 4.3 x 2.8 x 1.7 cm forming a mass consistent with CT findings (Fig. 1C). Muscle layer of the appendix was intact, but subserosal inflammatory cell infiltration was noted (Fig. 1D). Storiform fibrosis or obliterative phlebitis was absent; however, immunohistochemical (Fig. 1E) revealed that > 50% of IgG cells were IgG4 cells, consistent with IgG4-related disease.