Scintigraphic Diagnosis of Intrathoracic Splenic Implants Masquerading as Malignancy

DISCUSSION

Because of the patient’s remote history of gunshot wound to the abdomen and evidence of posttraumatic splenectomy more than 20 years previously, the soft-tissue masses were easily confirmed as being of splenic origin. Tobacco use increases the incidence of malignancy in the lungs, gastrointestinal tract, liver, kidneys, and bladder (1), among other locations. Unexplained ectopic tissue in these organs must therefore be further worked up. Similarly, splenic implants may be mistaken for lung cancer (2), renal cancer, and peritoneal seeding in patients with a history of bladder carcinoma, primary or metastatic hepatic malignancy (3), or nonmalignant causes such as endometriosis (4). Given the patient’s long history of smoking, the likelihood of malignancy could not be comfortably excluded and further work-up was necessary.

In a patient with a history of trauma requiring splenectomy, we may expect to find splenic implants in the abdomen and pelvis, with intrathoracic implants being a remote possibility. According to the 2015 ACR-SPR guidelines for spleen scintigraphy, if there is suspicion that trauma may have ruptured the diaphragm, the chest should be imaged as well. (5). Additionally, in an effort to preserve some immune functionality, surgeons may attempt autotransplantation of splenic tissue, which will then be evident on imaging with ^99mTc-labeled heat-damaged red blood cells or ^99mTc-labeled sulfur colloid (6). Figure 2 demonstrates increased radiotracer uptake by the pulmonary masses in the thorax after injection of ^99mTc-labeled sulfur colloid, demonstrating benign ectopic intrathoracic splenosis.