Case Presentation: A 50-year-old female with history of prior tobacco use, fibromyalgia, presented to the pulmonary clinic for evaluation of pleural based lung masses seen on an outpatient CT abdomen. Her past medical history was notable for splenectomy after a motor vehicle accident in her early 20s. Other injuries at that time included a pelvic fracture, bilateral collapsed lungs. She was up to date on her cancer screening. She quit smoking about 5 years prior and had a 30-pack year history. She denied asbestos exposure or other environmental exposures. She was adopted and did not know her family history. She denied any respiratory symptoms. Other than chronic joint and muscle pain, review of systems was negative. She could not recall having a CT chest in the past. Her physical examination was unremarkable. CT chest with contrast was done to further assess the pleural masses. CT showed homogeneously enhancing left pleural implants most likely consistent with thoracic splenosis(TS). A nuclear-medicine heat damaged RBC scan was recommended for confirmation. Given the non-availability of this test at our institution, a nuclear medicine Technetium 99-m Sulfur Colloid Liver/Spleen scan was done which revealed intrathoracic and abdominal splenosis as suggested by multiple foci of increased sulfur colloid uptake in the left paravertebral region, left hemithorax and left side of abdomen.
Discussion: Splenosis is defined as ectopic auto transplantation of splenic tissue after splenic rupture or splenectomy. It most commonly occurs in the abdomen or pelvis after seeding of serosal surfaces followed by progression to nodules of splenic tissue. TS can be seen in about 18% of individuals who have combined diaphragmatic and splenic injuries. The average time between trauma and diagnosis is18.8 years, however it can be anywhere between 1 and 42 years. TS is a benign condition often found incidentally as asymptomatic pulmonary nodules. Some patients can present with cough, hemoptysis. It can raise concern for malignancy prompting invasive work-up. However, detailed history and nuclear medicine studies can obviate the need for invasive studies. A 99 m technetium-labelled heat-damaged red cell scan is considered the gold standard for detection of splenosis. Technetium-99 m sulfur colloid scintigraphy is a reliable means of differentiating splenic tissue from non-splenic tissue. Although it is not as specific as heat-damaged red cell scintigraphy, Tc-99 m Sulfur Colloid Liver-Spleen scan has the advantage of being more readily available, simpler, and less time consuming. Management of TS is typically conservative. Surgical options should only be considered in patients with symptoms or when malignancy cannot be ruled out completely. Nodule excision should be avoided to prevent operative risks of excessive bleeding.
Conclusions: With increasing prevalence of CT scans, the frequency of diagnosis of splenosis is expected to increase. As internal medicine physicians, we need to have a high index of suspicion for thoracic or abdominal splenosis when encountering a patient with history of trauma or splenic surgery together with suggestive findings on imaging. This will prevent unnecessary and potentially dangerous invasive diagnostic procedures like biopsy and thoracotomy. As with our patient, getting a thorough history may lead to an answer to the mystery, as these patients usually present more than two decades after the splenic traumatic rupture.