Schwannomas are benign, slow-growing tumors that arise from the Schwann cells of peripheral nerve sheaths and are also known as neurilemmomas or neurinomas. These tumors are covered with a well-demarcated capsule and commonly measure 2-4 cm in diameter. They frequently occur in the head and neck or in the extremities. The lesions themselves do not cause an inflammatory reaction, and patients usually present when these lesions compress the associated peripheral nerve and cause sensory or motor issues secondary to neuropathy. Schwannomas do not have a predilection for sex or ethnicity, but tend to develop between the second and fifth decades of life. Surgical resection is curative, and the possibility of recurrence or malignant transformation is considered extremely low [1,2]. Schwannomas of the intercostal nerve are extremely rare with few cases of large or symptomatic lesions reported in the literature. No intercostal schwannomas have been reported as an incidental finding. Here, we report a small intercostal schwannoma found during a chest wall reconstruction. A 58-year-old male patient with a sternal mass underwent excisional biopsy of a sternal lesion. The mass was found to be a chondrosarcoma on histopathology, and the patient subsequently underwent a secondary operation for wide resection and reconstruction of the chest wall defect. In the operating room, the sternal mass was resected en bloc with a wide surgical margin. In order to restore the resulting chest wall defect, a composite island flap was elevated, including the left tenth rib and the latissimus dorsi muscle. During this process, a 1-cm×1-cm mass was incidentally found along the subcostal groove of the tenth rib (Fig. 1). This well demarcated mass was excised. The remainder of the operation was uneventful. The results of the histologic examination of this lesion were consistent with a schwannoma (Fig. 2). Upon inquiry, the patient did report occasional bouts of pain in the area, which was described as sharp stabbing pain that worsened with coughing and exercise. However, the preoperative chest computed tomography images did not indicate the presence of the intercostal schwannoma. He did not report any paresthesia or hypoesthesia in the area innervated by the tenth intercostal nerve. The patient was discharged 14 days after the operation without any complications. The patient did not report any subsequent episodes of the pain. Fig. 1 (A, B) Intraoperative photographs. A 1-cm×1-cm mass was incidentally found under the left tenth rib. Fig. 2 Histopathologic images of the specimen. (A) The low-power view shows a biphasic pattern with a cellular Antoni A area (black arrow) and a hypocellular Antoni B area (white arrow) (H&E, ×40). (B) The high-power view shows tumor cells forming ... The most common presentation of schwannomas is a palpable mass, the percussion of which result in a painful paresthesia along the involved peripheral nerve [3]. In the case described here, the patient recalled a sharp shooting pain along the tenth intercostal nerve distribution of the left chest wall that worsened with coughing and exercise. While uncommon, schwannomas of the intercostal nerve can grow to compress the nerve against the subcostal groove, causing intercostal neuralgia, including pain, tenderness, paresthesia, and hypoesthesia. Chronic intercostal neuralgia is relatively common among adults, and is caused by herpes zoster infection, diabetic polyneuropathy, vertebral facet joint hypertrophy or arthritis, and malposition of the costovertebral joint (slipping rib syndrome) [3]. Intercostal neuralgia can also be caused by tumors and/or inflammation in the mediastinal, paravertebral, and costal areas [4]. The intercostal schwannoma and neuralgia in our case did not cause significant disability to the patient, which was most likely due to the fact that the lesion was smaller than most intercostal schwannomas (1 cm×1 cm compared to the usual size of 2-4 cm). The intercostal nerves are a part of the somatic nervous system, and originate from the anterior root of the thoracic spinal nerve (T1-T12). Each intercostal nerve is responsible for the sensation of the skin and parietal pleura and the motor activation of the intercostal muscle at its respective level. Since the tenth intercostal nerve is not responsible for significant sensory or motor function, we were able to completely excise the schwannoma in our patient without any morbidities or complications. This patient was a very rare case of intercostal schwannoma. The small tumor was responsible for intercostal neuralgia. Such small intercostal schwannomas are difficult to detect clinically because the intercostal nerve is located deep in the chest wall and may not be apparent in radiologic studies. However, larger lesions may involve the surrounding tissue and cause symptoms such as pleural effusion, dyspnea, and Horner's syndrome [5]. Therefore, incidentally found intercostal schwannomas, although generally benign and asymptomatic, should be excised to prevent the development of symptoms or complications from further growth.
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Open Access
Jan 1, 2019
Yasser Ali Kamal 
