Renomedullary Interstitial Cell Tumor in Pregnancy: A Review Article with a Case Presentation

Introduction: Renomedullary interstitial cell tumor (RICT), or medullary fibroma, is a small tumor that is usually asymptomatic unless it attains a significant size; in rare cases, the tumor may be large and symptomatic. These benign tumors have a specific histology. Although they are usually incidental findings, it is necessary to be able to discriminate this lesion from other malignancies of the kidney, especially since its management represents a challenge during pregnancy. Numerous patients undergo an unnecessary radical nephrectomy to diagnose renal masses, which is considered hazardous for pregnant women. Ultrasound is the imaging procedure of choice followed by the magnetic resonance imaging (MRI) for assessing the urinary system in pregnant women. Histopathological examination is considered mandatory for the diagnosis of RICT to preclude an unnecessary nephrectomy. Case Presentation: In November 2015, a 31-year-old pregnant woman at gestational week 12 of her second pregnancy was referred to our private clinic in Rasht, Iran. She had microscopic hematuria; a mass measuring 39 × 33 mm in the upper portion of her right kidney was was detected by ultrasonography. Conclusions: A percutaneous renal mass biopsy was used, instead of nephrectomy, to diagnose the mass; immunohistochemical reports showed that the morphologic features were not compatible with an epithelial neoplasm and the paucicellular spindle cell tumor was compatible with renomedullary interstitial cell tumor. Patients with RICT can be successfully managed using a percutaneous renal mass biopsy and avoiding unnecessary nephrectomy.