Design: Retrospective analysis of our experience.

Setting: Department of Thoracic and Cardiovascular Surgery, Nara Medical University.

Patients: From January 1992 to August 2002, 13 patients with a SFTP were referred to us for surgical resection after VATS was adopted in our hospital. The study group consisted of seven men and six women with a mean age of 49.8 years (age range, 37 to 72 years).

Results: Surgical excision was performed with VATS only in nine patients, with VATS plus a small thoracotomy in three patients, and by a posterolateral thoracotomy without VATS in one patient. The mean chest-drain duration was 1.3 days (range, 1 to 3 days), and the mean duration of hospital stay was 8.6 days (range, 3 to 30 days). Eleven tumors, originating from the visceral pleura, were pedunculate, and 2 tumors from the parietal pleura were not pedunculate. Two cases were focally characterized by a mitotic count in excess of four mitoses per 10 high-power fields and by cellular pleomorphism. Follow-up periods ranged from 6 to 120 months, with a mean of 49.7 months and a median of 42 months. All patients have remained well with no recurrence or metastasis.

Conclusions: Complete surgical resection is the treatment of choice for SFTPs. For the pedunculate tumors, therefore, VATS is a powerful and useful approach. Even when it is necessary to perform a small thoracotomy in addition to VATS for the removal of a large tumor, VATS may play an important role in reducing the size of the thoracotomy incision, which results in less invasive surgery. To minimize postoperative morbidity, VATS may be the most promising surgical approach for the resection of SFTPs. (CHEST 2004; 125:1144-1147)

Key words: pleura; solitary fibrous tumor; video ,assisted thoracoscopic surgery

Abbreviations: HPF = high-power field; SFTP = solitary fibrous tumor of the pleura; VATS = video assisted thoracoscopic surgery

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Primary tumors of the pleura are divided into the following two major categories: diffuse and solitary. (1-3) Diffuse pleural tumors, which are associated with exposure to asbestos, arise from mesothelial tissue, have poor prognosis, and are more common than solitary pleural tumors. (4-6) On the other hand, a solitary fibrous tumor of the pleura (SFTP) is a slow-growing neoplasm, with approximately 800 cases having been reported in the literature to date. (7) In 1931, Klemper and Rabin (8) differentiated a diffuse type of SFTP that arose from the mesothelial layer of a localized form that arose from file mesothelial fibrous connective tissue. SFTPs are usually discovered as asymptomatic lesions on routine chest radiographs in adult patients with no evidence of asbestos exposure. Although they may be relatively large, they are usually treated by simple excision and do not recur if their resection is microscopically complete. (9,10) The literature on SFTPs suggests that tumor size, increased mitoses, increased cellularity, increased nuclear pleomorphism, hemorrhage, and necrosis may be associated with clinical behavior. (10,11) In addition, some authors describe the presence of a histologically malignant component, with increased cellularity and mitoses, in otherwise benign-appearing SFTPs as a frequent occurrence in tumors that recur or metastasize. (9-12)

Recently, the use of video-assisted thoracoscopic surgery (VATS) was introduced for the diagnosis and treatment of intrathoracic lesions. VATS is thought to be minimally invasive and, thus, is perceived to result in less postoperative pain and quicker recovery. (13,14) The aim of tiffs study was to summarize our experience in the management of SFTPs and to evaluate the advantage of VATS for the treatment of SFTPs.

MATERIALS AND METHODS

From January 1992 to December 2002, 13 patients with SFTPs were referred for surgical resection at Nara Medical University Hospital after VATS was adopted in our hospital. Our series included seven men and six women with a mean age of 49.8 years (age range, 37 to 72 years) [Table 1]. The preoperative follow-up period was 2.8 years (range, 1 to 6 years) in the outpatient clinic of other hospitals. The tumor was right-sided in eight patients (61.5%) mad left-sided in five patients (38.5%). None of the patients was symptomatic or presented with a history of hypoglycemia, but five of them were associated with diabetes mellitus. No history of exposure to asbestos was recorded in any patient. Ten of the patients were current smokers or ex-smokers. All patients underwent chest roentgenography and CT scanning of the chest. Three patients (23.1%) underwent CT-guided, fine-needle aspiration biopsy.

The diagnosis was confirmed by corroborative morphologic and immunohistochemical findings that are available for review. The pathologic diagnostic criteria of SKIP used were circumscribed tumors characterized by a haphazard growth pattern (so-called patternless pattern or storiform pattern) of short spindle cells with scant cytoplasm and bland cytologic appearance, separated by strands of rope-like collagen. Typically, these tumors exhibit an alteration of hypercellular (ie, collagen-rich) areas. (5,6,9) Small to large numbers of blood vessels were observed. The malignant variant was macroscopically similar to the benign tumor, but contained high mitotic activity, which was defined as at least four mitotic figures per 10 high-power fields (HPFs), necrosis, and mild-to-marked pleomorphism, based on nuclear size, irregularity, and the presence of nuclear atypia. (5,7,12,15) Clinical information was obtained by means of hospital records and telephone calls to patients.

RESULTS

Resection was completed in all our patients. Surgical excision was performed by VATS in nine patients (69.2%), by VATS plus a small thoracotomy (< 5 cm) in three patients (23.1%), and by posterolateral thoracotomy accompanied by VATS in one patient (7.7%) [Table 2]. Mean chest drain duration was 1.3 days (range, 1 3 days), and the mean hospital stay was 8.6 days (range, 3 to 30 days). The perioperative mortality rate was 0%. At surgery, 11 tumors (84.6%) arising from the visceral pleura were pedunculate, and 2 tumors (15.4%) from the parietal pleura presented with a broad base of attachment (Table 2). All tumors were resected with free surgical margins. In two patients, a pleural effusion was observed in the ipsilateral thoracic cavity. Grossly, the tumors appeared well-circumscribed, polylobulated, with a smooth surface and firm consistency. They measured from 25 x 15 x 15 mm to 120 x 80 x 40 mm. On sectioning, the tumors showed a whorled, fleshy appearance, sometimes alternating with some myxoid areas. Focal necrosis and hemorrhagic zones were found in two cases (15.4%), both relatively large in diameter. Microscopically, all the tumors consisted of spindle-shaped cells. The tumor cells and intercellular collagen fibers proliferated without obvious direction or structure, Milch corresponded to the so-called "patternless pattern." Two cases (15.4%) were focally characterized by a mitotic count in excess of four mitoses per 10 HPFs and by cellular pleomorphism (Tables 2 and 3). Immunohistochemical analysis revealed positivity for CD34 and vimentin in all tumors, and no expression of cytokeratin, desmin S-100, Ki-67, or actin in any of the tumors.

All patients were included in a follow-up program that included clinical examination and chest roentgenogram after 1, 3, and 6 months postoperatively, and annually thereafter. Follow-up took place until December 2002, and ranged from 6 to 120 months in length, with a mean of 49.7 months. All of the patients have remained well, with no recurrence or metastasis of the tumors.

DISCUSSION