Accessory spleen mimicking a pancreatic tumour

Clinical History

An 18-year-old male patient with sporadic abdominal pain.

Imaging Findings

CT demonstrated a mass in the pancreatic tail, the arterial phase showing a heterogeneous enhancing mass (arrow), the portal venous phase showing homogeneous enhancement (Fig. 1, 2).
On MRI the pancreatic mass showed a similar signal intensity to that of the adjacent normal spleen on all sequences (Fig. 3, 4).

Discussion

Accessory spleen is a congenital abnormality that consist of foci of splenic tissue that are separate from the main body of the spleen [1]. Accessory spleens are seen in 10-30% of patients at autopsy [2].
The majority of cases are asymptomatic, so it is usually an incidental finding on imaging studies.
The second most common location in an autopsy study was the pancreatic tail (16.8%) [2].
It typically appears as a small and solid enhancing mass with a smooth, round or ovoid shape. The same as in a normal spleen, accessory spleens may demonstrate heterogeneous and serpiginous enhancement in the early CT phase because of the different rates of flow through the cords of the red and white pulp [3]. On venous phase CT it shows same pattern of contrast enhancement as the spleen.
On MRI the key for diagnosing accessory spleens is that their signal intensity is identical to those of the spleen on all the sequences including dynamic studies [4].
It is important to characterize accessory spleens to obviate unnecessary treatment or surgery.

Differential Diagnosis List

Final Diagnosis

Intrapancreatic accessory spleen

URL:	https://www.eurorad.org/case/13815
DOI:	10.1594/EURORAD/CASE.13815
ISSN:	1563-4086