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Figure 1. Chest radiograph demonstrating a large right-sided chest mass compressing the right upper lobe of the lung.
Figure 2. Computed tomographic scan of the chest demonstrating compression of the right upper lobe of the lung secondary to a mass.
The mass was confirmed to be a benign neurilemoma, with less than 1 mitosis per 25 high-power fields. Magnetic resonance imaging performed before the operation showed no sign of spinal extension of the tumor. Intraoperatively, it appeared to originate from a thoracic nerve. Despite the large size of the tumor, we found no signs or symptoms of von Recklinghausen disease.
Neurogenic tumors account for 75% of all tumors located in the posterior mediastinum.1 A neurilemoma, or schwannoma, is a benign, slow-growing tumor that often arises from the nerve sheath of a spinal nerve. Approximately 90% of all neurilemomas originate in the posterior mediastinum. Infrequently, they have a thoracic origin from one of the intercostal nerves.2
Thoracic neurogenic tumors are often associated with von Recklinghausen disease.1,3 However, isolated thoracic neurilemomas also occur with no other associated abnormality. They can grow to a large size, but are usually less than 10 cm in diameter. The most commonly reported signs and symptoms associated with neurilemomas are Horner syndrome, radiculopathy, bony abnormalities, dyspnea, pulmonary compression, and pleural effusions. Forty percent of patients remain asymptomatic, even when spinal extension of the tumor has occurred.4
Because the tumor has small malignant potential, and because of the likelihood of compression of surrounding organs and the technical difficulty of resecting such large masses, observation of benign neurilemomas is not advisable.3 Ten percent of schwannomas will grow into dumbbell tumors of the spinal cord, requiring a well-planned combined thoracic and neurosurgical approach.4 Complete resection of tumors with benign histological findings requires no further treatment.
Corresponding author: Gregory P. Victorino, MD, Department of Surgery, University of California–San Francisco, East Bay, 1411 E 31st St, Oakland, CA 94602.
Image of the Month—Diagnosis. Arch Surg. 2003;138(3):342. doi:10.1001/archsurg.138.3.341