Intrapulmonary Solitary Fibrous Tumors

Abstract

Solitary fibrous tumor (SFT) is a ubiquitous neoplasm that arises most commonly from the pleura. SFT arising within lung parenchyma (intrapulmonary SFT) has been rarely reported and is therefore not well recognized. We present a clinicopathologic and immunohistochemical study of 24 cases of primary intrapulmonary SFT. Patients' ages ranged from 44 to 83 years (mean, 58 y). None of the patients had evidence or history of a similar tumor elsewhere. Tumor size ranged from 2.3 to 22 cm (mean, 8.5 cm). On the basis of the degree of cytologic atypia, cellularity, mitotic activity, and areas of necrosis, the lesions were divided into low-grade, intermediate-grade, and high-grade histology. Twenty-one tumors showed the conventional features of SFT of low-grade histology (<5 mitoses per 10 high-power fields), with alternating bands of rope-like collagen flanked by a bland-appearing spindle cell proliferation. Hemangiopericytic, angiofibromatous, and a neural-like plexiform growth pattern were also observed. Five of 21 cases showed an "adenofibromatous" appearance imparted by entrapped normal airspaces at the advancing edges of the lesion. One intermediate-grade tumor showed overall increased cellularity with plump, pleomorphic nuclei, 5 to 10 mitoses per 10 high-power fields, and focal areas of classic SFT. Two cases showed high-grade features at initial presentation, with areas resembling a pleomorphic high-grade sarcoma admixed with foci of conventional, low-grade SFT. Immunohistochemical staining analyses performed in 13 cases showed positivity of the tumor cells for CD34, bcl-2, and CD99 in the majority of cases tested. Clinical follow-up was available in 18 patients, with long-term follow-up (>5 y) in 6. Fourteen (14/18) patients were alive and well without evidence of disease 1 month to 14 years after initial diagnosis. Three patients died of their tumors after 4, 5, and 7 years; in 2 of them the initial tumor was of low-grade histology, but the recurrence/metastases showed a high-grade histology; the third fatal case showed a tumor with high-grade histology at initial diagnosis. One patient with intermediate-grade histology also had chest wall metastases at 5 years but was subsequently lost to follow-up. The results of our study indicate that although tumors with overtly malignant histologic features can be expected to behave as high-grade sarcomas, tumors with bland-appearing morphologic features at presentation may also follow an aggressive behavior. Adequate excision with close clinical follow-up, thus, appears to be the most prudent course of action for the management of primary intrapulmonary fibrous tumors.

Solitary Fibrous Tumors of Chest: Another Look with the Oncologic Perspective

“…SFT typically appear as masses abutting the pleura; most often arising from the lung visceral pleura (≈80% of cases) (13), but occasionally with apparent origins from the mediastinal (≈1-8% of cases) or parietal pleura (2,12,13,16,17). Given the close proximity of the various pleural surfaces to each other, the precise origin/extent of these lesions can be uncertain (Figure 1,2,3,4).…”

Variable Solitary Fibrous Tumor Locations

“… 4 – 10 An SFTs diagnosis is characterized by the proliferation of spindle mesenchymal cells and positive immunohistochemical staining for CD34. 11 , 12 Approximately 78% to 88% of SFTs are benign, but 12% to 22% are malignant. 13 , 14 The age-standardized incidence of SFTs is reported to be 1.4 per million 15 and their rarity, diverse localizations, and difficulty of predicating tumor biological behaviors have limited the attempts to obtain CT and MRI data to better characterize their features.…”

Solitary fibrous tumor of the spermatic cord: A case report and literature review

“…Previous studies have confirmed that tumor markers, including CD34 + , Bcl-2 + and CD99 + , are generally positive in SFT cases, which has aided the diagnosis of SFTs ( 17 , 18 ). Currently, the positive staining of CD34 + is indispensable in the diagnosis of an SFT; however, the expression of CD34 is not limited to SFTs ( 11 ).…”

“…Usually, an SFT is defined as a benign form of tumor due to its low rates or even absence of local recurrence and metastasis, as demonstrated by a number of previous studies ( 1 , 2 , 22 , 23 ). However, an increasing number of recent studies have demonstrated that a considerable number of SFTs are malignant ( 11 , 18 , 24 ). In the case of an SFT which is unresectable, metastatic or has positive surgical margins, patients are unlikely to benefit significantly from radiotherapy or chemotherapy; the alternative treatments for an SFT ( 2 ).…”