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Postgraduate Education Corner: PULMONARY AND CRITICAL CARE PEARLS |

A 37-Year-Old Woman With an Incidentally Found Mediastinal Nodule* FREE TO VIEW

Gijs Limonard, MD; Joris Joosten, MD; Yvonne Berk, MD; Ineke De Kievit, MD, PhD; Saskia Zomer, MD; Mariël Keemers, MD, PhD
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*From the Departments of Pulmonary Diseases (Drs. Limonard and Berk), General Surgery (Drs. Joosten and Keemers), and Pathology (Drs. De Kievit and Zomer), Canisius-Wilhelmina Hospital, Nijmegen, the Netherlands.

Correspondence to: Gijs Limonard, MD, Department of Pulmonary Diseases, Canisius-Wilhelmina Hospital, Weg door Jonkerbos 100, 6525 SZ Nijmegen, the Netherlands; e-mail: g.limonard@cwz.nl



Chest. 2008;133(6):1508-1511. doi:10.1378/chest.07-2513
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A 37-year-old woman presented with a sudden onset of right-sided chest pain and dyspnea the day after she underwent an abdominal hysterectomy for excessive menstrual bleeding. The pain was constant and worsened with breathing. Medical history was significant for a splenectomy following a motor vehicle accident at the age of 9 years. She had a 20–pack-year history of smoking. A pulmonary embolism was suspected. Multidetector-row spiral CT of the chest showed compression atelectasis of the basal segments of the right and left lower lobes but no pulmonary embolism. Unexpectedly, a well-circumscribed, homogeneously enhanced mediastinal nodule 15 mm in diameter was seen in the anterior superior mediastinum (Fig 1 , left, A). With analgetic treatment, she was discharged free of symptoms on the seventh postoperative day. At the following visit to the Department of Pulmonary Diseases, she denied any complaints. Physical examination and laboratory findings were unremarkable. In addition to the known mediastinal nodule (Fig 1, left, A), conventional contrast-enhanced chest CT revealed the presence of a pleural nodule 5 mm in diameter located anterolaterally in the left hemithorax (Fig 1, right. B). The patient underwent video-assisted thoracoscopic surgery. The mediastinal nodule seen on CT correlated with a reddish pedunculated nodule closely adherent to the left superior mediastinum (Fig 2 , left, A). Several other, smaller pleural-based lesions with a similar appearance were noted (Fig 2, right, B). The mediastinal nodule was resected and sent for pathologic examination (Fig 3 ). The other lesions were left intact.

Thoracic splenosis is the autotransplantation of viable splenic tissue into the left pleural cavity following splenic injury and concomitant rupture of the left hemidiaphragm. Once implanted, the ectopic splenic tissue derives its blood supply from the surrounding pleura and typically grows into mature splenic tissue over the course of several years. A return of immunologic and hematologic function of the “born-again” spleen can occur. Children who undergo splenectomy for traumatic splenic rupture have a lower incidence of sepsis, as compared to splenectomy for any other indication. The higher incidence of thoracic splenosis in male patients probably reflects the higher involvement of male subjects in traffic accidents and subsequent thoracoabdominal trauma. The interval between trauma and diagnosis ranges from 3 to 45 years (average, 21 years). The condition is rare, with approximately 50 cases reported in the literature, but the true prevalence is likely to be underestimated because up to 18% of all cases of splenic rupture have thoracic splenosis when followed up prospectively. Furthermore, thoracic splenosis is usually asymptomatic and only discovered incidentally as a pleural nodule or mass on chest imaging studies. In the literature, the only two reported presenting symptoms are hemoptysis and pleurisy.

CT scan typically shows nonspecific homogenously enhanced round or oval-shaped pleural nodules or masses in the left hemithorax, which are multiple in 75% of cases and solitary in 25%. Differential diagnosis includes pleural metastases of a solid tumor, lymphoma, invasive thymoma, asbestos-related pleural plaques, mesothelioma, and neurogenic tumors. Conventional MRI scanning does not narrow this differential diagnosis. Ferumoxide-enhanced MRI scanning may be helpful, but to our knowledge, only one case report using this radiologic technique has been published for thoracic splenosis. The current diagnostic noninvasive technique of choice is nuclear scintigraphy. Using the unique ability of the reticuloendothelial system to filter out platelets, damaged, or aged erythrocytes, and sulfur colloid particles, nuclear scintigraphy with 99mTc heat-damaged erythrocytes, 111In-labeled platelets, or 99mTc sulfur colloid can accurately detect any ectopic splenic tissue. Definite data on the performance in terms of sensitivity and specificity of nuclear scintigraphy in the detection of thoracic splenosis are not available because (to our knowledge) no studies have compared nuclear imaging findings with tissue diagnosis in large series. In the setting of abdominal splenosis and when compared directly with the sulfur colloid test, scintigraphy using 99mTc heat-damaged erythrocytes has a 32% greater diagnostic yield.

As most thoracic splenosis lesions are pleural based and the workup is that of a potential malignancy, percutaneous fine-needle aspiration or Tru-Cut biopsy (Baxter; Deerfield, IL) can provide a tissue diagnosis when nuclear scintigraphy fails to detect ectopic splenic tissue. The histologic finding of splenic white or red pulp is diagnostic. Fine-needle aspiration cytology can be misleading though because the presence of lymphoid tissue is highly indicative of lymphoproliferative disease.

Once thoracic splenosis is confirmed by noninvasive techniques, no further workup is needed unless the patient is symptomatic. Pleurisy resolves spontaneously or is easily controlled by analgetics. Hemoptysis due to hypervascular nodules has been managed successfully with surgery. Although no long-term adverse sequelae or deaths have been reported with thoracic splenosis, most authors recommend follow-up with serial chest radiographs.

As in many case reports on thoracic splenosis, we did not consider this diagnosis preoperatively in our patient and we did not perform preoperative nuclear scintigraphy. The actual differential diagnosis was that of a lesion in the anterior mediastinum and focused on lymphoma, invasive thymoma or, less likely, teratoma. During video-assisted thoracoscopic surgery, multiple lesions with similar appearance became apparent. There were no obvious signs of a former rupture of the left hemidiaphragm. However, the surgeons did not explicitly search for a former rupture because still the diagnosis was not suspected during this procedure. The mediastinal lesion was resected to obtain the diagnosis. The pathologic specimen was consistent with normal splenic tissue. The residual ectopic splenic tissue may protect this patient against overwhelming sepsis. Since the chest pain after the hysterectomy was exclusively right sided, we do not believe this symptom to be related to her left-sided thoracic splenosis. Furthermore, no infarction or bleeding in the resected nodule was noted on the pathology report. In retrospect, given the patient’s medical history, the diagnosis of thoracic splenosis should have been considered and appropriate radionuclide imaging would have obviated the need for video-assisted thoracoscopic surgery.

  1. Thoracic splenosis should be considered in any patient presenting with a thoracic lesion and a history of thoracoabdominal trauma with splenic injury or splenectomy.

  2. Thoracic splenosis generally presents as an incidental finding in chest imaging studies, but cases of hemoptysis and pleurisy have been documented.

  3. Radionuclide imaging studies confirm the diagnosis of thoracic splenosis and obviate the need for invasive diagnostic procedures.

  4. Thoracic splenosis is considered to be a benign condition and, unless symptomatic, requires no specific treatment.

  5. Ectopic splenic tissue can be immunologically and hematologically functional and may protect against overwhelming sepsis.

The authors have no conflicts of interest regarding this article to disclose.

Figure Jump LinkFigure 1. CT scan of the chest showing a well-circumscribed, homogeneously enhanced nodule in the anterior superior mediastinum (left, A) and a smaller, pleural-based nodule anterolaterally in the left hemithorax (right, B) [white arrows].Grahic Jump Location
Figure Jump LinkFigure 2. Thoracoscopic view of the pedunculated nodule adherent to the left superior mediastinum (left, A) and a similar, pleural-based lesion laterally in the left hemithorax (right, B).Grahic Jump Location
Figure Jump LinkFigure 3. Photographic image of the original hematoxylin-eosin–stained slide of the excised nodule; within the inset (hematoxylin-eosin, original × 100), a close-up of the tissue with the aspect of red and white pulp.Grahic Jump Location
Alaraj, AM, Chamoun, RB, Dahdaleh, NS, et al (2005) Thoracic splenosis mimicking thoracic schwannoma: case report and review of the literature.Surg Neurol64,185-188. [PubMed] [CrossRef]
 
Cordier, JF, Gamondes, JP, Marx, P, et al Thoracic splenosis presenting with hemoptysis.Chest1992;102,626-627. [PubMed]
 
Fremont, RD, Rice, TW Splenosis: a review.South Med J2007;100,589-593. [PubMed]
 
Gopal, KG, Jones, MT, Greaves, SM An unusual cause of chest painChest2004;125,1536-1538. [PubMed]
 
Normand, JP, Rioux, M, Dumont, M, et al Thoracic splenosis after blunt trauma: frequency and imaging findings.AJR Am J Roentgenol1993;161,739-741. [PubMed]
 
Pearson, HA, Johnston, D, Smith, KA, et al The born again spleen: return of splenic function after splenectomy for trauma.N Engl J Med1978;298,1389-1392. [PubMed]
 
Tsunezuka, Y, Sato, H Thoracic splenosis; from a thoracoscopic viewpoint.Eur J Cardiothorac Surg1998;13,104-106. [PubMed]
 
Yammine, JN, Yatim, A, Barbari, A Radionuclide imaging in thoracic splenosis and a review of the literature.Clin Nucl Med2003;28,121-123. [PubMed]
 

Figures

Figure Jump LinkFigure 1. CT scan of the chest showing a well-circumscribed, homogeneously enhanced nodule in the anterior superior mediastinum (left, A) and a smaller, pleural-based nodule anterolaterally in the left hemithorax (right, B) [white arrows].Grahic Jump Location
Figure Jump LinkFigure 2. Thoracoscopic view of the pedunculated nodule adherent to the left superior mediastinum (left, A) and a similar, pleural-based lesion laterally in the left hemithorax (right, B).Grahic Jump Location
Figure Jump LinkFigure 3. Photographic image of the original hematoxylin-eosin–stained slide of the excised nodule; within the inset (hematoxylin-eosin, original × 100), a close-up of the tissue with the aspect of red and white pulp.Grahic Jump Location

Tables

Suggested Readings

Alaraj, AM, Chamoun, RB, Dahdaleh, NS, et al (2005) Thoracic splenosis mimicking thoracic schwannoma: case report and review of the literature.Surg Neurol64,185-188. [PubMed] [CrossRef]
 
Cordier, JF, Gamondes, JP, Marx, P, et al Thoracic splenosis presenting with hemoptysis.Chest1992;102,626-627. [PubMed]
 
Fremont, RD, Rice, TW Splenosis: a review.South Med J2007;100,589-593. [PubMed]
 
Gopal, KG, Jones, MT, Greaves, SM An unusual cause of chest painChest2004;125,1536-1538. [PubMed]
 
Normand, JP, Rioux, M, Dumont, M, et al Thoracic splenosis after blunt trauma: frequency and imaging findings.AJR Am J Roentgenol1993;161,739-741. [PubMed]
 
Pearson, HA, Johnston, D, Smith, KA, et al The born again spleen: return of splenic function after splenectomy for trauma.N Engl J Med1978;298,1389-1392. [PubMed]
 
Tsunezuka, Y, Sato, H Thoracic splenosis; from a thoracoscopic viewpoint.Eur J Cardiothorac Surg1998;13,104-106. [PubMed]
 
Yammine, JN, Yatim, A, Barbari, A Radionuclide imaging in thoracic splenosis and a review of the literature.Clin Nucl Med2003;28,121-123. [PubMed]
 
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