Introduction: Inflammatory myofibroblastic tumor (IMT) is a rare tumor that has been described in nearly every organ system in the body. IMT generally lack metastatic potential, but these tumors often exhibit locally invasive and progressive disease which can mimic locally advanced malignancy. In the genitourinary tract (GU), IMT can manifest with signs and symptoms (mass, hematuria, pain) of common GU cancers such as renal cell carcinoma, testicular mass, or transitional cell carcinoma of the bladder. Due to its novel nature and lack of a singularly agreed upon definition, IMT prevalence and incidence are difficult to ascertain. We conducted a comprehensive systematic review with the aim to identify all reports of IMT in the GU tract, and describe the presenting symptoms, contemporary management, and pathologic features.
Methods: Systematic review using the following search terms were performed: “Inflammatory Pseudotumor” OR “Pseudosarcoma” OR “Inflammatory Pseudo-Tumor” OR “Inflammatory Myofibroblastic Tumor” AND “Urology” OR “Urologic” OR “Genitourinary”. Two reviewers performed independent initial screening of all abstracts. All potentially eligible articles underwent full text review and data extraction. The data for each GU organ site was analyzed separately.
Results: Of the 259 articles initially identified, and 101 were used in the systematic review. The articles consisted primarily of small case series and case reports, for a total of 110 cases of GU IMT. Pediatric IMT accounted for 9% of GU IMT cases. Most common presenting symptoms included pain, mass, hematuria and voiding symptoms. The most frequently involved sites and treatment included bladder (63 cases; 52% had radical/partial cystectomy), kidney (19; 93% had radical/partial nephrectomy), epididymis (6), urachus (6), ureter (5), prostate (4), testis (4), and spermatic cord (3). Anti-inflammatory, antibiotic and antineoplastic therapy used in 8% of cases was ineffective. Anaplastic lymphoma kinase expression, noted in half the cases, is a favorable prognostic indicator. Incomplete excision is associated with risk of recurrence while complete surgical excision provides excellent disease control with rare recurrence or metastatic transformation ( <2%).
Conclusions: IMT exhibit locally invasive, symptomatic and progressive phenotype that can affect all GU organs, especially bladder, kidney and scrotal contents. Clinical and radiologic features mimic GU malignancy. IMT require complete surgical excision since incomplete resection increases the risk of symptomatic recurrence.