Solitary fibrous tumors of the pleura (SFTP) were first pathologically described by Klemperer and Rabin in 1931, and approximately 800 cases have been reported in the English literature [1
]. A review by Briselli and colleagues [2
] of 368 cases found that approximately 80% arise from the visceral pleura and 20% from the parietal pleura. The visceral pleural-based masses are typically pedunculated, encapsulated, peripheral masses with a well-vascularized stalk. Parietal-pleural based tumors are usually sessile and have a greater incidence of recurrence [3
]. In case reports, there have been accounts of SFTP located entirely within the lung parenchyma, with no gross relationship to the pleura.
Only 15 cases of intraparenchymal lung tumors have been described in the English literature, [1
], less than 2% of the roughly 800 reported cases. Proposed mechanisms for these atypical lung masses include (1) direct continuity of subpleural mesenchyma with the intralobular septae connective tissue, (2) origination of tumors from fibroblasts of the lung parenchyma itself, and (3) invagination of the visceral pleura, with mechanical forces causing growth away from the chest wall [6
]. The occurrence of SFTP in an endobronchial location is an even rarer finding; to our knowledge, there have only been two published instances [1
]. We report a case of an endobronchial SFTP that completely occluded the left mainstem bronchus and extended extraluminally into the subcarina.
A 55-year-old woman, who was a nonsmoker with a history of asthma, presented with recurrent pneumonias since January 2008. In February 2009, computed tomography scanning and bronchoscopy revealed a 2.1- × 1.4-cm mass within the left mainstem bronchus that extended into the subcarina, with postobstructive collapse of the lingula and left lower lobe (, ). Bronchoscopic biopsy revealed a solitary fibrous tumor.
Fig 1 Coronal reconstructed chest computed tomography image demonstrates (A) an enhancing 2.1- × 1.7-cm mass in the left main-stem bronchus (arrow) causing postobstructive atelectasis of the left lung preoperatively and (B) postoperative changes from (more ...)
Preoperative bronchoscopy reveals a completely occluding endobronchial mass in the left mainstem bronchus.
Immunohistochemistry staining was positive for cluster of differentiation 34, and negative for cluster of differentiation 31, cytokeratin 5/6, calretinin, cluster of differentiation 45, epithelial membrane antigen, cytokeratin 7, cytokeratin 20, pankeratin, S100, synaptophysin, and thyroid transcription factor 1. Preoperative pulmonary function tests revealed forced expiratory volume in 1 second of 1.43 (57% of predicted) and diffusion capacity of the lung for carbon monoxide of 81% of predicted. Quantitative lung perfusion study showed 9.5% left and 90.5% right lung perfusion.
In March 2009, the patient underwent surgical resection, which entailed left thoracotomy and en bloc sleeve resection of the left mainstem bronchus and subcarinal tumor, with bronchoplasty repair and intercostal muscle flap coverage of the primary anastomosis (). A left hilar pericardial release maneuver was performed to prevent tension on the bronchial anastomosis.
Gross specimen of the tumor demonstrates penetration through the bronchial wall with intraluminal (I) and extraluminal (E) protrusion. The arrow indicates bronchial wall cartilage.
Pathology revealed an intramucosal, 3.3-cm solitary fibrous tumor with rare mitoses (<1/10 high-power field) and no evidence of tumor necrosis or lymphovascular invasion (). The lymph nodes and margins were negative.
Fig 4 (A) The tumor is shown penetrating between plates of cartilage (double arrow). The single arrow indicates bronchial epithelium (hematoxylin and eosin stain, whole mount). (B) The tumor is composed of dense spindle cells infiltrating between submucosal (more ...)
The patient had an uneventful postoperative course and was discharged on postoperative day 9 without complications.
Postoperative pulmonary function tests at 6 months showed marked improvement, with a forced expiratory volume in 1 second of 2.02 (85%) and diffusion capacity of the lung for carbon monoxide of 99%. A chest computed tomography scan in August 2009 revealed no evidence of recurrent disease and complete left lung aeration (). She has not required the use of inhalers and remains asymptomatic.