Foschini M P, Scarpellini F, Rinaldi P, Mancini A F, Accinelli G, Eusebi V
Istituto di Anatomia ed istologia Patologica, Università di Bologna.
Pathologica. 1995 Dec;87(6):653-8.
Inflammatory pseudotumour (IPT) of the urinary bladder is a benign proliferative lesion which can simulate clinically and histologically a sarcoma. Aim of this study is to report four new cases and to review the literature.
Two patients were male, aged 2 and 4 years respectively (cases 1 and 2); cases 3 was a 26 year old woman and case 4 was a 40 year old man. Three patients presented with gross haematuria. One patient (case 4) presented with abdominal pain. On cystoscopy all the lesions presented as polypoid masses, ranging from 0.5 to 3 cm. in greatest axis. All patients were treated with conservative surgery. Case 1 died of unrelated causes 7 years later; at autopsy no evidence of residual bladder lesion was found. All the remaining three patients are alive and free of disease 8, 4, and 3 years respectively.
On histology all the lesions had similar features. They were characterized by a submucosal growth of spindle cells with little pleomorphism, immersed in abundant myxoid stroma. In all cases immunoreactivity with vimentin was obtained; smooth muscle actin was focally positive in two cases and cytokeratin in one case. Bladder muscular wall was involved in three cases.
The present four cases showed same histological and immunohistochemical feature of the IPTs previously described in the literature. IPT of the urinary bladder must be differentiated from malignant lesions such as rhabdomyosarcoma, leiomyosarcoma, inflammatory fibrosarcoma, sarcomatoid carcinoma. Differential diagnosis is based mainly on the characteristic histological picture of IPT. Immunohistochemistry can be misleading as IPT shares in common with those malignant conditions, positivity with some markers, such as desmin with rhabdomyosarcoma and cytokeratin with sarcomatoid carcinoma.
