Prepared by Mitchell A. Miller, MD, Department of Radiology
and Peter Costantini, DO, Department of Pulmonary Medicine,
Atlantic City Medical Center, Pomona, NJ.
A 76-year-old man was admitted to the hospital because of a
persistent fever. His past medical history was remarkable for his
having undergone a splenectomy for treatment of a gunshot wound
during World War II.
A chest x-ray revealed left-sided pleural effusion with a
possible pleural-based mass (not shown). A subsequent computed
tomography (CT) examination demonstrated multiple high-attenuation,
pleural-based nodules in the left hemithorax and the absence of
normal splenic tissue in the left upper quadrant of the abdomen
(figure 1). Technetium-99mlabeled sulfur colloid scan demonstrated
absence of normal splenic uptake in the left upper quadrant and
multiple areas of abnormal radiopharmaceutical uptake in the left
hemithorax (figure 2).
Splenosis is the autoimplantation of splenic tissue from the
left upper quadrant to other sites, usually occurring after splenic
injury. Abdominal splenosis typically presents with multiple
nodules within the mesentery, peritoneum, and omentum. Thoracic
splenosis is rare and is seen in patients who have sustained
splenic trauma in association with traumatic rupture or tearing of
the diaphragm. This entity was first described by Shaw and Shafi
in 1937 as an autopsy finding in a patient who had undergone
previous posttraumatic splenectomy. In a 1993 review of 17 cases of
posttraumatic splenosis, the mean interval between trauma and
imaging studies was 5.1 years with a range of 2.7 to 7.9 years.
More recently, the diagnosis has been reported within 1 year of the
Most patients with thoracic splenosis are asymptomatic, although
a patient presenting with hemoptysis has been reported.
This is in contrast to abdominal splenosis, which may present with
abdominal pain or small-bowel obstruction.
Peripheral blood smears may demonstrate findings typically seen in
asplenic individuals, specifically absence of Howell-Jolly bodies
as well as the presence of pitted erythrocytes and siderocytes.
Chest radiographic findings in thoracic splenosis demonstrate
multiple pleural-based nodules in the left hemithorax. On CT, the
pleural-based nodules demonstrate attenuation characteristics
similar to the spleen. The nodules have been reported to range in
size from <1 cm to 6 cm.
On MRI, the nodules demonstrate signal intensity and enhancement
characteristics identical to normal splenic tissue.
However, none of the radiographic, CT, or MRI findings are
pathognomonic for thoracic splenosis. Therefore, other differential
diagnostic considerations include metastatic pleural disease
(including lung and breast cancer) and lymphoma. If only a solitary
pleural nodule is present, mesothelioma and benign fibrous tumor of
the pleura should be included in the differential diagnosis.
Historically, the diagnosis of thoracic splenosis has been made
at thoracotomy; typical findings include multiple reddish-brown
pleural-based nodules ranging in size from 3 mm to 6 cm.
The diagnosis can also be confirmed noninvasively with radionuclide
studies. Several authors have documented the diagnosis of thoracic
splenosis using radionuclides that localize to the spleen.
Commonly used agents include Technetium-99m sulfur colloid,
Technetium-99mlabeled heat-damaged red blood cells, and Indium 111
platelets. Typical findings, as in this case, include absence of
the normal splenic uptake of tracer with multiple areas of abnormal
uptake in the left hemithorax.
The diagnosis of thoracic splenosis should be considered in
patients who present with multiple pleural-based masses on chest
x-ray or CT in which a history of significant trauma (usually
requiring splenectomy) can be elicited. The diagnosis can be
confirmed with noninvasive radionuclide studies, thereby obviating
the need for additional diagnostic studies, including open
thoracotomy and biopsy.