A 63-year-old man with a history of radical prostatectomy for prostate carcinoma was diagnosed as having synchronous rectosigmoid adenocarcinoma and ileal carcinoid. He underwent a sigmoid colectomy, right hemicolectomy and defunctioning ileostomy, which was successfully reversed 1 month later.

On a follow-up CT scan at 6 months, a 9 mm soft tissue density nodule was identified in the left upper quadrant lateral to the spleen, which was not present previously, raising the suspicion of a peritoneal deposit. However on careful review of the patient’s previous CT scans, this was shown to represent a highly mobile splenunculus on a long vascular pedicle that had moved from the splenic hilum to the lateral aspect of spleen (fig 1).

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Figure 1

A 9 mm splenunculus ((A), arrow) on an 8 cm vascular pedicle ((A), arrowhead). The splenunculus was noted on the anterior aspect ((B), arrow) and splenic hilar region ((C), arrow) on previous scans.

Single or multiple splenunculi are a common finding on modern cross-sectional imaging and rarely present a diagnostic challenge.1 A mobile splenunculus however, as in this case, is a rare condition1 that may be misdiagnosed as a new peritoneal or metastatic deposit. The important diagnostic features are changing position on interval scanning and identification of a vascular supply.

This case highlights the importance of having a high index of suspicion for splenunculi on cross sectional imaging scans in malignancy staging as they occasionally show marked mobility with the potential for misinterpretation.2^,3 A diligent search for a vascular supply and a careful review of previous imaging should confirm the diagnosis. Follow-up imaging may be required when findings are inconclusive.