A 60-year-old woman presented with several years of dull left upper quadrant, mid-epigastric, and right flank pain. Abdominal CT showed multiple soft tissue densities of unclear etiology. She reported having a post-traumatic splenectomy in the 1960s. A technetium-99m-labeled heat-damaged RBC scan (Tc99m-dRBC) demonstrated radiotracer uptake in the left upper quadrant, posterior to the right kidney, and along the right diaphragm, confirming ectopic splenic deposits (Fig. 1).

Fig. 1
figure 1

Maximum intensity projection (MIP) anterior and posterior images of Tc 99 m scan showing increased radiotracer uptake in three separate splenic tissue deposits in the left upper quadrant measuring 2.3, 2, and 1.5 cm (red arrows), a 1.7 cm subphrenic deposit beneath the right diaphragm (blue star), and a 3 cm deposit posterior to the right kidney (green arrowhead), all correlating with her sites of discomfort.

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Disseminated splenosis (DS) is a benign condition caused by metastatic deposits of splenic tissue following trauma or surgery. DS is usually asymptomatic and diagnosed incidentally by ultrasound or computed tomography, but can cause site-specific discomfort mimicking endometriosis or peritoneal metastases.1 Other reported complications include gastrointestinal bleeding, bowel obstruction, and hydronephrosis.2 Nuclear scintigraphy with Tc99m-dRBC localizes ectopic splenic tissue based on the increased uptake of damaged erythrocytes within the reticuloendothelial system.3, 4 In the setting of previous splenic trauma, this noninvasive technique is a sensitive and specific tool to establish the diagnosis, potentially avoiding invasive tissue sampling or diagnostic laparoscopy.5 Patients with DS may retain partial immunoprotection from encapsulated organisms,6 but no studies have shown an optimal approach to assessing residual splenic function.7