The incidence of left iliac fossa uptake of (99m)Tc-DTPA in renal scanning.

In rare cases, extrarenal uptake of technetium-99m diethylenetriamine penta-acetic acid ((99m)Tc-DTPA) has been reported, e.g. in tumours or abscesses. Although in our experience a relatively common occurrence, increased uptake in the left iliac fossa (LIF) and its incidence have not been described. This retrospective study set out to establish the incidence of this phenomenon and to exclude malignancy as the cause. All patients who had a renal (99m)Tc-DTPA scan between 1 January 1996 and 31 December 1997 had their scans reviewed. Presence and grade of increase in iliac fossa activity were determined by consensus agreement of three observers. The list of patients with increased uptake was cross-referenced against the New South Wales (Australia) Cancer Council database to exclude the possibility of a neoplastic lesion in this region. Increased LIF uptake was noted in 41 of the 231 (18%) consecutive patients (18 men, 23 women; mean age 43 years, range 20-83). Among these 41 patients, uptake was severe in 2 (5%), moderate in 12 (29%) and mild in 27 (66%). No patient had increased uptake in the right iliac fossa. Only one patient had a malignant lesion but this was excluded as being the cause of LIF uptake. No other patient developed malignancy (mean follow-up time 4.1 years; range 3.2-5.1). Increase in LIF uptake is a common, benign finding most likely due to activity within the descending colon. It occurs in approximately 18% of the population, and it is important to recognise such uptake in order to avoid misdiagnoses.