Mediastinal schwannoma diagnosed by endoscopic ultrasonography-guided fine needle aspiration cytology

Efficacy of endoscopic ultrasound-guided fine-needle aspiration for schwannoma: six cases of a retrospective study

BACKGROUND

Schwannomas are difficult to diagnose using imaging alone. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is an effective and safe tissue sampling technique. Nevertheless, few reports have described EUS-FNA for schwannoma.

OBJECTIVE

This study evaluates the efficacy of EUS-FNA for diagnosing schwannoma.

METHODS

This retrospective study examined six consecutive schwannoma patients who were diagnosed as having schwannoma either from EUS-FNA results or from surgically resected specimens. The primary endpoint was diagnostic accuracy of EUS-FNA for schwannoma. The secondary endpoint was EUS-FNA safety.

RESULTS

Based on cytomorphologic features and immunocytochemistry results after EUS-FNA, 4 out of 6 patients (66.7%) were diagnosed with schwannoma. The diagnoses before EUS-FNA were the following: 3 cases of gastric subepithelial lesion (SEL, suspicious for gastrointestinal stromal tumor), 1 case of intraperitoneal tumor, 1 case of retroperitoneal tumor, and 1 case of pancreatic tumor, with sizes of 15-44 mm (median 36 mm). No case was diagnosed as schwannoma solely based on image findings. Two cases of gastric SELs could not be diagnosed as schwannoma by EUS-FNA before surgery. Inadequate sampling and a lack of additional material for immunohistochemical studies could have engendered less-definite diagnoses in those cases. No procedural adverse events occurred.

CONCLUSION

The diagnostic accuracy rate of EUS-FNA for schwannoma is somewhat low. However, tissue samples were obtained safely using this method. Moreover, it is an important procedure for diagnosing schwannoma, which cannot be diagnosed solely from image findings.

An Unusual Presentation of a Posterior Mediastinal Schwannoma Associated with Traumatic Hemothorax

Schwannomas of the thoracic cavity are typically an asymptomatic, benign neurogenic neoplasm of the posterior mediastinum. In this case, we present a traumatic hemothorax as the initial presentation for a previously undiscovered mediastinal mass. The patient presented with shortness of breath and right-sided chest pain after being struck in the chest with a soccer ball. An operative exploration was pursued due to persistent hemothorax with hemodynamic instability despite resuscitation and adequate thoracostomy tube placement. The intraoperative etiology of bleeding was discovered to be traumatic fracture of a large hypervascular posterior mediastinal schwannoma. Surgical resection is the treatment of choice for these tumors. Specific serological markers do not exist for this tumor, and radiographic findings can be variable, so tissue diagnosis is of importance in differentiating benign from malignant schwannomas, as well as other posterior mediastinal tumors. However, most patients have excellent survival following complete resection.

Malignant peripheral nerve sheath tumor of the anterior mediastinum: a rare presentation

Malignant peripheral nerve sheath tumor (MPNST) is a rare tumor that accounts for 5% of all thoracic neoplasm usually located in the posterior mediastinum and is generally associated with a poor outcome. We present a case of MPNST of the anterior mediastinum presenting in a rare location leading to diagnostic dilemmas and treated primarily by surgical resection.

Gastric schwannoma diagnosed by endoscopic ultrasonography-guided trucut biopsy

Schwannomas of the gastrointestinal (GI) tract are rare subepithelial tumors comprising approximately 3.3% to 12.8% of all mesenchymal tumors of the GI tract. On endoscopic ultrasound (EUS) they are seen as hypoechoic tumors arising most commonly from the 4th proper muscle layer. Although EUS helps to distinguish tumor characteristics, tissue sampling is required for differentiation with other more common tumors such as GI stromal tumors. Both EUS-guided fine needle aspiration and EUS-guided trucut biopsy (EUS-TCB) can be used for tissue sampling. However, only EUS-TCB allows core biopsy and a high yield of immunohistochemical staining. We report a case of a gastric schwannoma diagnosed by EUS-TCB.