Inflammatory pseudotumor of the urinary bladder with aberrant expression of cytokeratin - Report of a case with cytologic, immunocytochemical and cytogenetic findings

BACKGROUND: Cytologic descriptions of inflammatory pseudotumor of the urina ry bladder are exceedingly rare. We describe here an additional ase of this disease, including it cytologic features and aberrant expression of cytoke ratin CASE: A 35-year-old male presented with gross hematuria but not history of bladder surgery. Urine cytology revealed a few atypical spindle cells suspi cious for sarcoma. Histologically, the lesion consisted of spindle cells of various sizes and shapes, proliferating in irregularly running bundles, bu t no severe nuclear atypia or pathologic mitosis was found. Immunocytochemi cally, these cells were unexpectedly positive for cytokeratin as well as fo r vimentin and muscle actin. All metaphase cells examined revealed a normal male karyotype. CONCLUSION: Inflammatory pseudotumor must be distinguished in particular fr om leiomyosarcoma and spindle cell carcinoma. To avoid an erroneous diagnos is, recognition of tis entity is important, together with careful histologi c examination and awareness of the possible aberrant expression of cytokera tin.