Ann Thorac Surg 2008;86:1362-1364. doi:10.1016/j.athoracsur.2008.03.031
© 2008 The Society of Thoracic Surgeons
Case Reports
Inflammatory Myofibroblastic Tumor Mimicking Anterior Mediastinal Malignancy
Chih-Hao Chen, MDa,
Rong-Luh Lin, MDb,
Hung-Chang Liu, MDa,
Chao-Hung Chen, MDa,
Tzu-Ti Hunga,
Wen-Chien Huang, MDa,*
a Department of Thoracic Surgery, Mackay Memorial Hospital, Taipei City, Taiwan
b Department of Chest, Mackay Memorial Hospital, Taipei City, Taiwan
Accepted for publication March 19, 2008.
* Address correspondence to Dr Huang, No 92, Section 2, Chung Shan North Road, Taipei City, Taiwan (Email: musclenet2003{at}yahoo.com.tw).
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Abstract
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Inflammatory myofibroblastic tumor arising in the anterior mediastinum is rare. A 58-year-old woman had an anterior mediastinal mass invading the sternum, pericardium, and pleura. It was completely resected and found to be an inflammatory myofibroblastic tumor. The patient was well and had no recurrence 6 months after surgery.
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Introduction
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Inflammatory myofibroblastic tumor is a rare disease most commonly found in the lung, liver, or spleen. It has been rarely reported to arise purely from the mediastinum [1, 2].
A 58-year-old woman complained of chest wall pain, discomfort, and mild dyspnea for months, which did not resolve spontaneously. She denied any history of fever, weight loss, trauma, or foreign travel. On physical examination, she was alert and her vital signs were normal. No abnormalities were found, including the chest examination. Initial chest roentgenogram showed a mass in the mediastinum and a left pleural effusion (Fig 1). A chest computed tomographic scan revealed an ovoid mass in the anterior mediastinum invading the sternum anteriorly and the pericardium posteriorly. In addition, there was a left pleural effusion and a pericardial effusion (Figs 2A and 2B). The mass had moderate, heterogenous contrast enhancement. The computed tomographic appearance was suggestive of a thymic carcinoma. A percutaneous needle biopsy was performed, but the specimen contained only muscle fibers, a result that was attributed to an inadequate biopsy. The patient declined a second diagnostic biopsy, opting instead for surgical resection. Preoperative serum tumor markers, including alpha-fetoprotein, human chorionic gonadotropin, squamous cell carcinoma, carcinoembryonic antigen, and Cancer Antigen 19-9 were within normal limits.
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Fig 1. Preoperative chest roentgenogram showing mediastinal widening and pleural effusion suggestive of a malignant mediastinal lesion.
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Fig 2. Chest computed tomographic scan showing (A) an anterior mediastinal mass with heterogenous contrast enhancement apparently invading the sternum, but with a clear plane between separating it from the aorta and the pulmonary vessels, and (B) pericardial effusion and left pleural effusion.
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A midline sternotomy was performed, and the mass was seen to adhere firmly to the bone, requiring a partial sternal resection to remove the tumor. The lesion had a firm capsule in most areas, except for the planes between the mass and the pericardium and pleura. Partial resection of the pericardium and the left pleura were also necessary to remove the 9 x 7 x 4 cm mass completely. There was a clear, serous pericardial effusion and a bloody pleural effusion, samples of which were sent for cell blocks and cytology.
A thin but dense capsule covered most of the surface, except where it was adherent to the sternum (Fig 3A), the pericardium, and the pleura. The texture of the cut surface was firm with focal cystic changes, hemorrhage, and fibrous bundles interweaving through the tumor (Fig 3B). Pathologically, the mass was composed of both acute and chronic inflammatory cells, including neutrophils, macrophages, plasma cells, lymphocytes, histiocytes, and scattered proliferating spindle cells. On immunohistochemical staining, the spindle cells were positive for smooth muscle actin, but negative for anaplastic lymphoma kinase, CD30, CD15, and S-100. These findings were consistent with a diagnosis of inflammatory myofibroblastic tumor. No malignant cells were found in either effusion sample. The patient was discharged 8 days after the operation, and at a 6-month visit, she was well with no evidence of recurrence.
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Fig 3. (A) Gross appearance of the resected mass with hemorrhage in the central part that had been adjacent to the sternum. (B) Cut surface of the solid mass showing a fibrous capsule, focal cystic changes and necrosis, and interweaving fibrous tissue.
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Comment
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The cause, pathogenesis, and long-term prognosis of inflammatory myofibroblastic tumor are unclear. Based on the pathology features, it was once believed to be purely an inflammatory process [3, 4]. However, in 2000, Lawrence and colleagues [5] reported rearrangement of the anaplastic lymphoma kinase gene in some cases of inflammatory myofibroblastic tumor. Because it may invade adjacent structures, as in our patient, and may have distant metastasis, it is now viewed as a true neoplasm of spindle cells in a background of inflammatory cells. Antecedent infections have been noted in approximately 30% of reported cases. Our patient denied any such history, and because the majority of cases have not been associated with infection, it is not clear whether there is any real association with an infectious process. Inflammatory myofibroblastic tumor is difficult to differentiate from other neoplasms prior to operation. Radiographic findings are not reliable for diagnosis [4, 6, 7]. A biopsy specimen may be diagnostic, although in the absence of obvious malignant features, one must question the adequacy of the specimen. This was true in our case.
As with any unusual lesion whose nature and pathogenesis is somewhat obscure, it is hard to gather hard evidence on effective treatment. Surgical resection seems to be the treatment of choice [3, 4, 8]. Chemotherapy, steroids, and radiation therapy have all been tried, but their effectiveness is unclear. Antibiotics alone have no obvious place in the management. The reported outcome of inflammatory myofibroblastic tumor after complete resection is excellent [3, 4, 8].
This case is a reminder of the uncertainty we face in routine medical practice. The approach to our patient was based on a presumed diagnosis of thymic carcinoma, a disease that is not particularly unusual. The true nature of the mass was totally unexpected, but the management was still appropriate, and thus far it seems to have been curative.
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References
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- Yamaguchi M, Yoshino I, Osoegawa A, et al. Inflammatory myofibroblastic tumor of the mediastinum presenting as superior vena cava syndrome J Thorac Cardiovasc Surg 2003;126:870-872.[Free Full Text]
- Gorospe L, Fernandez-Gil MA, Torres I, et al. Misleading lead: inflammatory pseudotumor of the mediastinum with digital clubbing Med Pediatr Oncol 2000;35:484-487.[Medline]
- Cerfolio RJ, Allen MS, Nascimento AG, et al. Inflammatory tumors of the lung Ann Thorac Surg 1999;67:933-936.[Abstract/Free Full Text]
- Melloni G, Carretta A, Ciriaco P, et al. Inflammatory tumor of the lung in adults Ann Thorac Surg 2005;79:426-432.[Abstract/Free Full Text]
- Lawrence B, Perez-Atayde A, Hibbard MK, et al. TPM3-ALK and TPM4-ALK oncogenes in inflammatory myofibroblastic tumors Am J Pathol 2000;157:377-384.[Abstract/Free Full Text]
- Berman M, Georghiou GP, Schonfeld T, et al. Pulmonary inflammatory myofibroblastic tumor invading the left atrium Ann Thorac Surg 2003;76:601-603.[Abstract/Free Full Text]
- Agrons GA, Rosado-de-Christenson ML, Kirejczyk WM, et al. Pulmonary inflammatory tumor: radiologic features Radiology 1998;206:511-518.[Abstract/Free Full Text]
- Bahadori M, Liebow AA. Plasma cell granulomas of the lung Cancer 1973;31:191-208.[Medline]
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Abstract
Introduction
