|Year : 2016 | Volume
| Issue : 2 | Page : 72-74
Solitary intrathoracic neurofibroma
Obinna Innocent Orakwe1, Kenneth Etukokwu1, Emeka Onwukamuche2, Nobert Iziga1, Chinyere Onyenwuzo1, Jonathan Nwiloh1
1 Dr. Joe Nwiloh Heart Center, St Joseph's Hospital, Adazi Nnukwu, Nigeria
2 Department of Pathology, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra State, Nigeria
|Date of Web Publication||16-Dec-2016|
Obinna Innocent Orakwe
Dr. Joe Nwiloh Heart Center, St Joseph's Hospital, Adazi Nnukwu, Anambra State
Source of Support: None, Conflict of Interest: None
Neurofibroma and schwannoma are rare benign peripheral nerve sheath tumors and both combined account for the majority of intrathoracic neurogenic tumors seen in adults. They are difficult to distinguish clinically except by immunohistochemistry. A 50-year-old female nonsmoker presented with a 2-year history of right-sided chest pain, cough, and shortness of breath. Chest X-ray showed a large right chest mass confirmed on chest computed tomography scan and measured 14 cm Χ 15 cm Χ 10 cm. The patient subsequently underwent a right posterolateral thoracotomy with complete resection of the tumor, which was diagnosed on immunostains as a neurofibroma. At 1-year follow-up, the patient remains asymptomatic with no evidence of recurrent tumor.
Keywords: Diagnosis, neurofibroma, resection
|How to cite this article:|
Orakwe OI, Etukokwu K, Onwukamuche E, Iziga N, Onyenwuzo C, Nwiloh J. Solitary intrathoracic neurofibroma. Niger J Cardiovasc Thorac Surg 2016;1:72-4
| Introduction|| |
Schwannoma and neurofibroma combined account for up to 90% of intrathoracic neurogenic tumors in adults.  They both originate from the peripheral nerve sheath and are generally slow-growing benign tumors (peripheral nerve sheath tumor [PNST]). Schwannomas are composed of Schwann cells which normally produce the insulating myelin sheath covering the peripheral nerves, while neurofibromas arise from nonmyelinated nerve sheaths. The clinical presentation and treatment for both these benign PNSTs are similar, and differentiation usually by immunohistochemistry is therefore often only of academic importance. However, there are instances of certain hereditary syndromes where distinction between the two varieties may have clinical relevance.
| Case Report|| |
A 50-year-old female nonsmoker was referred to our center with a 2-year history of insidious onset and progressively worsening right-sided chest pain. The pain was described as constant with radiation to the back and relieved with analgesics. She later developed a nonproductive cough and shortness of breath with moderate exertion. She denied any hemoptysis, fever, night sweats, anorexia, or weight loss. There is no prior history of chest trauma or family history of von Recklinghausen's disease. On examination, she was alert and in no acute respiratory distress at rest. Breath sounds were absent in the right middle and lower chest on auscultation. Resting oxygen saturation on room air was normal at 98%. Chest X-ray revealed a homogenous opacity in the lower half of the right chest [Figure 1]. Chest computed tomography (CT) scan confirmed a large intrathoracic mass measuring 14 cm × 15 cm × 10 cm which was separate from the lung and with no extension into the neural canal [Figure 2]. Ancillary laboratory hematologic and chemistry investigations were all within normal limits. She subsequently underwent a right posterolateral thoracotomy with complete resection of the tumor. The tumor was firm with vascular adhesions to the surrounding structures, especially to the diaphragm. Tumor was also attached by a stalk to the mediastinal pleura at about the 7 th /8 th vertebra [Figure 3]. The postoperative course was uneventful. Tumor was diagnosed as a neurofibroma on immunohistochemistry [Figure 4] and [Figure 5]. At 1-year follow-up, the patient remains asymptomatic with no evidence of recurrence.
| Discussion|| |
Neurogenic tumors are reported to account for 15%-30% of mediastinal masses, which is lower than the incidence of thymomas and lymphomas.  Primary mediastinal masses when discovered on radiological imaging studies can usually be narrowed down to a few differential diagnosis depending on location, patient's age, and symptoms. The PNST schwannoma and neurofibroma make up to 90% of intrathoracic neurogenic tumors in adults. Schwannoma is more common and accounted for 43% and 55% compared to neurofibroma 32.5% and 14% in 2 large adult series of intrathoracic neurogenic tumors. , The peak age of incidence for schwannoma is 20-50 years and for neurofibroma 20-40 years although they may appear earlier in patients with von Recklinghausen's disease. Pavlus et al.  in an attempt to aide preoperative radiologic diagnosis identified some imaging features and distinguishing CT and magnetic resonance imaging characteristics between the two. Schwannoma on unenhanced CT scan shows well-marginated soft-tissue mass with possible surrounding fat attenuation (split fat sign), may contain areas of low attenuation corresponding to fat or cystic degeneration, and calcification may be seen in 10% of tumors. While neurofibroma appears as sharply marginated smooth or lobulated mass of soft tissue density with possible split-fat sign, pressure erosion on adjacent structures, and possible calcifications, these radiologic characteristics are however not definitive but only a guide. Differentiating between schwannoma and neurofibroma is usually confirmed with immunostains in most cases, although this is not usually of great clinical importance except in von Recklinghausen's disease, where there is a 2%-5% risk of malignant transformation with neurofibroma. These PNSTs are generally slow growing but may eventually become symptomatic from expansion of the nerve and or compression of surrounding structures. About 10% of neurogenic paravertebral tumors may have an extension into the vertebral canal so-called Dumbbell tumors although this has rarely been reported with neurofibroma.  Takeda et al. in their 50 years' review consisting of 146 patients with intrathoracic neurogenic tumors found that about two-third (67.1%) were asymptomatic, and the tumors were discovered incidentally on routine chest X-rays. They also found that 20.5% of the tumors were malignant and occurred predominantly within the first 5 years of life. In almost all cases of intrathoracic tumors, surgical excision is required both for diagnostic and therapeutic purposes. Complete resection is usually curative for benign tumors with reported very low rates of recurrence in 1.1%.  Video-assisted thoracoscopic surgery (VATS) is the recommended preferred approach when feasible because of its lower morbidity and quicker recovery compared to thoracotomy. VATS should however be utilized only when there is no radiologic evidence of malignancy and tumor size <7 cm. , Our patient for instance had a huge tumor 15 cm in its widest dimensions that would not have been amenable to a minimally invasive VATS approach, and moreover, resectability was uncertain before surgery. PNSTs are rare, and they have been sparingly reported in the Sub-Saharan African region probably for multifactorial reasons including inadequate diagnostic tools.
| Conclusion|| |
Neurofibroma is a slow-growing PNST which is often an incidental finding on radiologic imaging in most patients at time of diagnosis. The finding of a suspected intrathoracic neurogenic tumor should warrant resection irrespective of the absence or presence of symptoms both for diagnosis and treatment. Complete resection when feasible is the treatment of choice as with our patient and this should provide a very low incidence of recurrence. 
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]