PMC4722666_01
(a) CT scan show 5-cm-wide mass lesion located at the right renal pelvis (arrow). (b) Gross examination of the resected specimen showing relatively well circumscribed whitish firm mass. The mass lesion is mainly located at the renal pelvis and blocking the ureter pathway as the ureter is seen in the right side of the mass lesion (arrow). Also renal parenchyma adjacent to the mass lesion seems to be involved
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Fig1
The lesion was in the renal pelvis, and as a result, hydronephrosis was also present (Fig 1a). The mass lesion was mainly located at the renal pelvis blocking the ureter pathway and renal parenchyma adjacent to the mass lesion also seemed to be involved (Fig 1b).
Histologic features of the mass lesion. (a) High power view showing storiform fibrosis with diffuse and intense inflammatory cell infiltration, mainly plasma cells and histiocytes. (b) Obliterative phlebitis is evident in some areas of the mass lesion. (c) Tubulointerstitium adjacent to the mass lesion showing fibrosis with abundant plasmacytic infiltration. (d) Immunohistochemically, IgG4-positive plasma cells infiltrated both the mass lesion and tubulointerstitium
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Fig2
Immunohistochemical staining revealed the presence of IgG4-positive plasma cells in both the mass lesion and tubulointerstitium (mean of 94/HPF per field) (Fig 2).