A Ball in the Door: An Obstructing Endobronchial Solitary Fibrous Tumor

Abstract

INTRODUCTION: Solitary fibrous tumors (SFT) are rare fibroblastic mesenchymal neoplasms that commonly arise in the thoracic cavity. They account for less than 2% of all soft tissue tumors. The most common site of SFTs is the pleura. Although they can arise from lung parenchyma, there is only case reports of endobronchial SFTs in the literature. CASE PRESENTATION:We present to you a 70 years old male, who presented with a prolonged history of a chronic cough for several months. Initial chest X-ray showed a left lower lobe nodule measuring 1.1 cm in size. A chest CT scan with contrast was performed and demonstrated a well-circumscribed 1.5 cm nodule located directly behind the segmental bronchus of the lingula. The nodule had low uptake on a PET scan performed one month later. A follow up CT chest with contrast performed 6 months after initial presentation showed an increase in nodule size to 2.1 cm. As a result, the patient underwent bronchoscopy and endobronchial ultrasound (EBUS). A left hilar lesion was visualized under EBUS, and multiple fine needle aspirations and a core biopsy were obtained. Using a flexible Olympic bronchoscope, the lesion was directly visualized inside the segmental bronchus of the lingula. The lesion was smooth-walled with ball-in-valve motion. The endobronchial lesion was excised using a hot snare. Pathology results revealed a spindle cell perforating where the spindle cells formed interlacing fascicles. The spindle cell nuclei appeared plump but lacked cytologic atypia. No mitotic activity was seen. Immunochemical stain was positive for CD-34, BCL-2, vimentin and desmin. Immunohistochemical stain for STAT-6 revealed diffuse strong positivity. Pathology findings were consistent with a solitary fibrous tumor. The patient underwent complete excision of tumor by thoracic surgery. Pathologic results were consistent with the initial findings, but mitotic activity was noted.DISCUSSION: SFT are extremely rare and can extend endo-bronchially and lead to obstruction. The clinical patterns and behavior of these tumors is unclear given their rarity. When benign, surgical resection is curative. Nonetheless, follow up is recommended since recurrence rate ranges between 10-18 precent of cases. Malignant SFTs have a higher rate of recurrence and mortality.CONCLUSIONS: SFTs are a rare fibroblastic neoplasms that arise mainly in the pleura. High level of suspicion is needed for diagnosis, and tissue biopsy to examine histology is crucial to distinguish between these findings.