[888] IgG4-Associated Inflammatory Pseudotumor of Ureter; a Report of Three Cases

SA Kim, SR Lee, J Huh, SS Shen, JY Ro. University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea; The Methodist Hospital, Weill Medical College of Cornell University, Houston, TX

Background: Inflammatory pseudotumors (IPT) are a generic term for a wide range of lesions characterized by proliferation of fibro-/myofibroblasts in the background of variable chronic inflammatory cell infiltration. Recently, IPT with abundant IgG4-positive plasma cells is considered to be a unique entity belonging to systemic IgG4-related sclerosing disease, and distinguished from other lesions in IPT category such as inflammatory myofibroblastic tumor (IMT) and fibrohistiocytic type IPT. IPT has been rarely reported in the ureter, and to the best knowledge, no ureter IPT in relation to IgG4-positive plasma cells has been described.
Design: We describe herein three cases of ureteral lymphoplasmacytic type (IgG4-associated) IPT with emphasis on their histologic and immunohistochemical features.
Results: Three patients, 45 and 47-year-old men and an 84-year-old woman presented with flank pain. Abdominal computed tomography revealed ureteral narrowing by a mass-effect and hydronephrosis in all cases (left, left and right ureter). Microscopic exam of the resected ureters revealed suburothelial mass-like lesions consisted of spindle-shaped fibro-/myofibroblasts without atypia, and abundant plasma cells. Eosinophils and dendritic or spindle-shaped histiocytes were scattered throughout. The ureteral lesion from the 47-year-old man extended to the periureteral adipose tissue and showed obliterative phlebitis. The lesion of the 84-year-old woman was accompanied with transitional cell carcinoma in situ in the overlying urothelium. On immunohistochemical studies, anaplastic lymphoma kinase (ALK) was negative and only a few fibroblasts/myofibroblasts were positive for smooth muscle actin (SMA). More than 50 plasma cells per one high power field were immunoreactive for IgG4 in all three cases, a diagnostic feature of IgG4-associated IPT. All three cases were treated with ureterectomy and alive and well with no evidence of recurrence.
Conclusions: Numerous IgG4-positive plasma cells, obliterative phlebitis, scattered distribution of eosinophils and dendritic histiocytes in IPT of our three cases were consistent with lymphoplasmacytic type IPT. These IgG4-related IPTs suggest that it would be interesting to review plasma cell-rich IPTs in other organs with regard to IgG4 and search for the features of systemic sclerosing disease.
Category: Genitourinary (including renal tumors)

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 84, Wednesday Morning


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