Intrathoracic neurogenic tumors are relatively rare. We present the case of a patient presenting with progressive dyspnea with tracheobronchial obstruction secondary to a massive intrathoracic malignant peripheral nerve sheath tumor.
A 23 year old male with no medical history presented to the emergency room with progressive dyspnea and worsening cough over the previous four weeks. Initial symptoms included low grade fever and non-productive cough. The patient also complained of intermittent, right-sided chest pain and on further questioning admitted to recent night sweats and unintentional weight loss. The patient’s vital signs on presentation were: T 36.3 C, HR 100, RR 26, BP 132/67, and SaO2 96% while breathing ambient air. Examination was significant for markedly decreased breath sounds over the right hemithorax and a small skin lesion in the region of the right eighth intercostal nerve. Chest x-ray revealed opacification of the right hemithorax with mediastinal shift to the left. Laboratory evaluation was unremarkable. CT of the thorax revealed a complex mass, 20 cm in diameter completely occupying the right hemithorax with chest wall invasion in the right eighth intercostal region along with right hemidiaphragm invasion and mediastinal deviation. The patient underwent biopsy of the chest wall lesion. Post-procedure the patient remained intubated and required ventilatory support with failure to wean. Bronchoscopy revealed extrinsic compression of the right main stem bronchus with significant [90%] extrinsic compression of the proximal left main stem bronchus. The left mainstem bronchus was opened with balloon dilation followed by Nintinol stent placement, which then allowed the patient to be successfully weaned off the ventilator and extubated. The histopathology was reported as malignant peripheral nerve sheath tumor. The patient was considered for chemotherapy as resection of the tumor was deemed not possible.
Neurogenic tumors arise from embryonic neural crest cells, which normally constitute ganglia, paraganglionic, and parasympathetic systems. Thoracic neurogenic tumors are most commonly found in either the costovertebral sulcus arising from the sympathetic chain or one of the rami of an intercostal nerve. These tumors are most often asymptomatic although infrequently dyspnea, cough, or other respiratory symptoms may be noted. (1) In adults, the malignancy rate of neurogenic tumors is less than 10% (and probably only 1 to 2%). (2) Malignant peripheral nerve sheath tumors (MPNST), sometimes referred to as malignant schwannomas, neurogenic sarcomas, and neurofibrosarcomas, are thought to arise de novo or from the transformation of a plexiform neurofibroma. Accordingly, although MPNST can occur in individuals in the general population, individuals with neurofibromatosis 1 have a significantly increased risk. (4) Clinically, these tumors are aggressive, locally invasive, and highly metastatic. (5) A review of the literature reveals that such tumors hardly ever reach such large size as in our case. Resection followed by radiotherapy and/or chemotherapy is the usual mode of treatment. We believe the tumor in this case arose from the eighth intercostal nerve.
Although relatively rare, malignant peripheral nerve sheath tumors must be included in the differential diagnosis of massive intrathoracic mass.
Bryan Barnosky, None.