Pleural Masses: A Case of Intrathoracic Splenosis Diagnosed Noninvasively

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Abstract Introduction Intrathoracic splenosis (IS) is defined by heterotopic autotransplantation of splenic tissue following trauma or surgery to the spleen. It almost always presents as left sided pleural based masses several years following splenectomy. Diagnosis can often be challenging without use of invasive means such as biopsy or video assisted thoracoscopic surgery (VATS) as it can mimic malignancy. Tc-99m-tagged heat-damaged RBC (Tc-99m-DRBC) scan can be used to detect all ectopic splenic tissue and should be used to diagnose IS noninvasively. Case Report A 62 year old male with a history of Heart Failure with Preserved Ejection Fraction (HFpEF) presented to the hospital with progressive dyspnea, weight gain and hypoxia. He has a remote history of gunshot wound and splenectomy in 1998. He was admitted for management of decompensated heart failure and was treated with aggressive diuresis with significant improvement of his hypoxia however, due to persistent oxygen requirement, a CT chest was obtained. CT found several left sided pleural based masses measuring up to 5.6cm in size which raised concern for the possibility of intrathoracic splenosis given the absence of spleen. The patient clinically improved with diuresis. Tc-99m-DRBC scan was obtained and demonstrated intense tracer uptake within lobulated foci along the left hemidiaphragm and left lateral aspect of the heart which confirmed the IS diagnosis. Discussion Intrathoracic splenosis is a rare disease that could occur after trauma or surgery to the spleen resulting from heterotopic autotransplantation of splenic tissue in the thoracic cavity. The mean interval between initial trauma and discovery of IS is 20 years. Most cases are discovered incidentally however some patients can develop pleuritic symptoms or hemoptysis. IS on imaging often presents as numerous homogenous left-sided pleural based masses. The imaging findings can often be concerning for malignancy – and the differential can include lymphoma, mesothelioma, and sclerosing hemangioma. Although it is a rare diagnosis, a high index of clinical suspicion should be maintained in patients with a history of abdominal trauma or splenectomy in order to avoid invasive procedures including percutaneous biopsy, VATS biopsy, and thoracotomy. Radionuclide “Spleen Scan” utilizes Tc-99m labeled heat-damaged erythrocytes and is a highly sensitive and specific modality for the diagnosis of intrathoracic splenosis as well as ectopic autotransplantation elsewhere including peritoneum and liver. Among patients with left sided pleural based masses it is important to inquire about any prior history of abdominal trauma which is instrumental in the diagnosis of IS noninvasively.

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