Potential clinical implications of an incidental renomedullary interstitial cell tumor in renal allograft biopsy.

Renomedullary interstitial cell tumors (RMICTs) are often incidentally detected lesions at autopsy or resection of the kidney for other reasons. The RMICTs have not been reported in renal allograft biopsy. Overall, given the clinical implications of the differential diagnosis considered, such as morphologically similar neoplasms, interstitial fibrosis and tubular atrophy (IFTA), amyloidosis, and oxalosis, it is prudent to exclude these by an appropriate workup. Once excluded, the patients can be reassured. However, regular follow-up is recommended due to the propensity of RMICT to increase in size with age.