Inflammatory myofibroblastic tumor of kidney together with ipsilateral perinephric and periureteric fibrosis

Rationale: Both inflammatory myofibroblastic tumor (IMT) and retroperitoneal fibrosis are rare lesions, but kidney involvement is more rare. It is the first study about IMT of the kidney in a patient with perinephric and periureteric fibrosis and we hold that fibroblast proliferation may be an intermediate status in oncogenesis of IMT. But further investigation is necessary in order to better clarify the relationship between fibroblast proliferation and IMT. Patient concerns: A 54-year-old female presented no positive signs except dull back pain after overwork. Diagnoses: On the basis of the urinary ultrasonography and computed tomography (CT) scan, we strongly suspected a renal cell carcinoma. Interventions: Considering the little remaining function of the right kidney and the possibility of malignancy, we performed a laparoscopic right radical nephrectomy. Outcomes: According to the analysis of the postoperative paraffin section and immunohistochemistry assay, a final diagnosis of IMT and retroperitoneal fibrosis nodules was made. Lessons: Both IMTs are rare lesions and its etiology and pathogeny are unclear. It is the first study about IMT of the kidney in a patient with perinephric and periureteric fibrosis. This report suggested that fibroblast proliferation may be an intermediate status in oncogenesis of IMT, but further investigation is necessary in order to better clarify the relationship between fibroblast proliferation and IMT. The preoperative diagnosis of renal IMT remains difficult. Preoperative fine-needle aspiration or percutaneous biopsy and intraoperative frozen section were applied to confirm the diagnosis to avoid unnecessary nephrectomy, especially in patients with renal insufficiency, bilateral masses, or a solitary kidney.