Till now, there were only a few numbers of publications reporting perforation of thoracic splenosis that presents as pulmonary lesion. Trauma is currently considered to be the main cause of splenic implantation. Previous report introduced multiple ectopic splenomegaly in the abdominal cavity and pelvic cavity after splenectomy due to trauma [
5]. Thoracic splenosis is an uncommon clinical entity and only accounts for less than 0.25% of splenectomies. Because conservative treatment for an asymptomatic splenosis is associated with a complication rate of 65%, [
6] the most treatment preferred for Thoracic splenosis is operation, including splenopexy or splenectomy, in uncomplicated and complicated cases. The vast majority of patients with heterotopic splenic tissues were characterized mainly as splenosis in abdomen or digestive system after splenectomy. In this case, although the previous operation notes at the time of the splenectomy did not mention any “escaped” spleen, the patient experienced splenic trauma with likely perforation of the left hemi-diaphragm and seeding of splenic tissue into the left thoracic cavity, which is most likely to be the source of thoracic splenosis.
Splenic implantation often occurs in the abdominal cavity, and often be misdiagnosed as malignant tumor of digestive system, such as liver cancer, gastric leiomyoma at the bottom, or mesothelioma. Ectopic spleen to the chest can be misdiagnosed as lung cancer [
7]. Thoracic splenosis usually presents as an incidental finding several decades after splenic trauma and rarely causes symptoms. In this case, the patient came to hospital for follow up check-up, further examination revealed masses in chest cavity, therefore, the thoracic splenosis in this case may be considered as incidental findings. Further surgery that was performed to remove splenosis may relief patient’s symptoms he already had for weeks.
Ultrasound, CT, and MRI etc. The diagnosis of thoracic splenosis cannot be made clearly through ultrasound, CT, or MRI, etc [
8]. Digital subtraction angiography (DSA) can show heterotopic spleen with an independent blood supply. Three-dimensional angiographic can clearly display the celiac axis or abdominal aorta main blood vessel, which provide great helps diagnosing ectopic splenic vascular remodeling. However, the structure of spleen-implanted reticular spleen-trabeculae was significantly reduced. There was no hilus of spleen and the blood supply came from the small vessels in the thoracic splenosis. Therefore, the diagnosis of thoracic splenosis may not be made through DSA. Splenosis on pleural may be misdiagnosed for an intrathoracic malignancy, which usually triggered prompted invasive investigation with needle or VATS biopsy. Previous reports suggested that when thoracic splenosis was suspected, the diagnosis may also be made on 99 m-Technetium heat-damaged erythrocyte scan, which has a high sensitivity and specificity for splenic tissue [
9]. A previous history of splenectomy would also be helpful for diagnosis. The incidence of heterotopic spleen is high in abdominal cavity and pelvic cavity, and splenic torsion could be easy to occur in wandering spleen [
10]. Most of the patients with thoracic splenosis had abdominal discomfort, but most of them had no obvious clinical symptoms. Clinical symptoms appear only when there was a twist or a pathological spleen. Surgical resection through laparoscopy is the main treatment for this type of heterotopic spleen [
11,
12]. However, surgical resection is not the first choice for multiple ectopic spleens. Small, asymptomatic thoracic splenosis can be monitored, but large ones that caused unendurable symptoms should be removed by surgery. Although the histology of thoracic splenosis resembles normal splenic tissue, it is still associated with reduced immune function as the residual volume and function is insufficient to confer protection against overwhelming post-splenectomy infection. Therefore, in principle, the implantation of asymptomatic thoracic splenosis may not necessarily be removed by surgery but the immunization and early prophylactic penicillin remains needed. Finally, a clear preoperative diagnosis is required to avoid unnecessary surgery [
13].