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73 yo male hypertension, incidental discovery of a thoracic mass. Endoscopic biopsy negative.

Patient hypertendu, 73 ans. Decouverte fortuite d'une masse thoracique.


Transthoracic biopsy evaluation proposed the diagnosis below, confirmed on the surgery specimen.

Specimen submitted mesures 16 cm in greatest diameter, lobulated, surgically easily removed, attached by a small pedicle to the pleura.


Cut surface shows a nodular pattern, with large whorled white areas. Other are soft, yellowish, with foci of necrosis.


Most of the sections observed disclose a fascicular , moderately cellular, collagen producing (Masson's Trichrome).


High Power, shows anisonucleosis, and dyscaryosis.

Low power, sharp margins of the nodules, and area of necrosis.


Hemangiopericytomatous pattern, focally observed.



High power view on the angiomatous foci.

Other areas (grossly, soft and yellowish), disclose a more cellular pattern.


These areas have a sarcomatous appearance.

Silver stain demonstrates, a less pronounced meshwork than observed in the previous fields.


High power view, discloses nuclear atypia, and high mitotic count.



Atypical mitotic figures are found.



CD 34 is positive, along with a high expression of p53. The other immunostains (cytokeratins, Actin, Desmin, and neural markers) are negative.




Malignant solitary fibrous tumor of the pleura.



About Solitary fibrous tumor of pleura


Solitary fibrous tumor of pleura (formerly called solitary fibrous mesotheliorna) is usually asymptomatic, although on occasion patients present with pain, cough, dyspnea, hypoglycemia-related symptoms, and/or prominent pulmonary osteoarthropathy that rapidly regress when the tumor is removed.This tumor is not associated with asbestosis. On rare occasions, it is found in association with a microscopically similar tumor in the peritoneum or retroperitoneum. Grossly, the lesion is well circumscribed, firm, lobulated, graywhite to yellow-white, with frequent whorling and fasciculation. The mean diameter is 6 cm. The appearance is reminiscent of uterine leiomyoma . Cystic degeneration is very unusual, but solitary fibrous tumor can present as a mural nodule within a large pleural-lined cyst. It may be found attached to the visceral pleura (80%) or parietal pleura, within an interlobar fissure, or sometimes within the lung parenchyma without a pleural connection.Lesions with an identical microscopic appearance occur in the peritoneum, retroperitoneurn (including kidney), mediastinum, nasopharynx, orbit, breast, and probably other sites.

Microscopically, both benign and malignant forms occur, the former greatly predominating. The distinction between them can be difficult.In the typical benign case, there is a tangled network of fibroblast-like cells, accompanied by deposition of abundant collagen fibers, many of which have a keloid-like quality. The degree of cellularity varies a great deal from area to area. Hemangiopericytornalike areas are frequent. The most cellular types may be misdiagnosed as fibrosarcoma or malignant schwannoma . If proper attention is paid to the lack of nuclear aberrations and the rarity or absence of mitoses, confusion is unlikely to occur. In some instances, clusters of cuboidal cells forming papillae, tubules, or solid nests are found at the periphery of predominantly fibrous tumors; these represent entrapped mesothelium. or bronchioloalveolar epithelium and should not be misconstrued as evidence of a biphasic composition of the tumor, as it has been done in the past.The malignant types are characterized by increased cellularity, atypia, mitotic activity, and necrosis.

This neoplasm has been regarded for many years as a form of mesotheliorna, largely on the basis of the pattern of growth that the tumor cells exhibit in tissue culture; however, on ultrastructural examination these cells show fibroblast-like rather than mesotheliallike features, and by immunohistochernistry they are reactive for vimentin and sometimes desmin rather than keratin. The most likely interpretation of this tumor, therefore, is that it arises from noncommitted mesenchymal cells present in the areolar tissue subjacent to the mesothelial lining.This has led to the proposal of alternative terms such as submesothelioma or submesothelial fibroma.

The tumor cells of this lesion stain strongly and consistently for CD34, a finding that may be of use in the differential diagnosis with some of the entities already described.

Almost 90% of these neoplasms are cured by surgical excision. In a thorough review of the literature, Briselli et al. found that 12% had caused death because of extensive intrathoracic growth. Indicators of good prognosis were presence of a pedicle, good circumscription, and absence of nuclear pleomorphism or mitotic activity.

(Ref. Ackerman's Surgical Pathology, 8 ed.)


Some recent abstract about Solitatry Fibrous Tumor of Plaura



Nihon Kokyuki Gakkai Zasshi 1999 Oct;37(10):834-40

Solitary fibrous tumor of the pleura with elevated high-molecular-weight insulin-like growth factor II and hypoglycemia.

Mori K, Ohtsuki Y, Hizuka N, Division of Internal Medicine, Syuso Public Hospital, Ehime, Japan.

Recurrent hypoglycemia occurred in a 58-year-old woman with a solitary fibrous tumor of the pleura and exhibiting CD34 immunopositivity. During episodes of hypoglycemia, serum high-molecular-weight insulin-like growth factor II (big IGF-II) was elevated. After removal of the tumor containing IGF-II, the hypoglycemia and serum big IGF-II disappeared. This was followed by an increase in normal IGF-II. We speculate that the primary cause of hypoglycemia in this patient was the presence of big IGF-II produced by the solitary fibrous tumor of the pleura. To our knowledge, the presence of this type of IGF-II in CD34+ solitary fibrous tumors of the pleura has not been described to date in the literature


Rev Clin Esp 1999 Jul;199(7):437-9

Solitary fibrous tumors of the pleura.

Roca Calvo MJ, Manes Bonet N, Alix Trueba A, Freixinet Gilart J. Servicio de Cirugia Toracica, Hospital Universitario Nuestra Senora del Pino, Las Palmas de Gran Canaria.

Seven cases of solitary fibrous tumours of the pleura are here reported, formerly named benign fibrous mesotheliomas. Histologically, these tumours are formed by fusiform cells with a minimal cellular pleomorphism and absence of mitosis. These tumours cause scarce symptoms which are usually diagnosed as a casual finding when a chest X-ray is performed on account of other cause. Treatment should be surgical, with removal of all tumoral mass, thus avoiding its growth and the possibility of the reported degeneration towards malignancy.


Chirurg 1999 Aug;70(8):949-52

Solitary fibrous tumors of the pleura.

Meyer M, Krause U Klinik fur Herz- und Thoraxchirurgie, Martin-Luther-Universitat, Halle-Wittenberg.

Solitary fibrous tumors of the pleura (SFTP) are very rare neoplasms. The majority of these tumors are benign, but about 10-20 % fulfill the criteria of malignancy. The clinical presentation varies according to the size and intrathoracic localization. In early stages, often asymptomatic, the tumors may grow to an enormous size and then cause symptoms such as cough, chest pain and dyspnea, but also paraneoplastic syndromes such as hypoglycemia or digital clubbing. Between 1981 and June 1998 we treated in our institution 16 SFTP in 14 patients (4 M, 10 F, average age at first operation 58 years). Eight patients showed symptoms, whereas in the other cases the tumors were found on routine chest X-rays. The usually pedunculated SFTP were completely resected without complications. Two patients developed malignant recurrences, which infiltrated the right upper lung lobe and the diaphragm respectively. In these cases the tumor was resected together with the adjacent structures. Since late recurrences are more often malignant than primary SFTPs long-term follow-up is mandatory even in benign lesions.


Ann Thorac Surg 1999 May;67(5):1456-9

Clinical behavior of solitary fibrous tumors of the pleura.

de Perrot M, Kurt AM, Robert JH, Borisch B, Spiliopoulos A Department of Surgery, University Hospital of Geneva, Switzerland.

BACKGROUND: Solitary fibrous tumors of the pleura are rare and presentunpredictable clinical behavior. METHODS: Between 1981 and 1998, 11 solitary fibrous tumors of the pleura were resected in 10 patients at the University Hospital of Geneva. Their clinical behavior and outcome were reviewed. RESULTS: Seven tumors arose from the visceral pleura, and three arose from the parietal pleura. Tumors arising from the parietal pleura were revealed to be more difficult to resect than those from the visceral pleura because of their size and adhesion to the chest wall requiring extrapleural resection. Eight tumors showed benign features, whereas two showed distinct features of malignity. One additional patient presented marked pleomorphism that could represent an intermediate form before frank malignity. Four tumors had been followed expectantly for 2 to 10 years before surgery. Although three enlarged rapidly, no signs of malignity were observed on histological examination. All patients are alive, from 2 months to 14 years after surgery (mean 55 months). In one case, however, a malignant tumor recurred 6 years after resection of a benign variant. CONCLUSIONS: Although histologically benign, solitary fibrous tumors of the pleura may enlarge rapidly and occasionally transform into malignant variants after several years. Therefore, complete surgical resection and long-term follow-up is recommended for all patients.


Can J Surg 1998 Dec;41(6):467-9

Metachronous benign solitary fibrous tumours of the pleura (localized "mesotheliomas"): a case report.

Urschel JD, Brooks JS, Werness BA, Antkowiak JG, Takita H Department of Thoracic Surgery, Roswell Park Cancer Institute, Buffalo, NY 14263-0001, USA.

Solitary fibrous tumours are uncommon pleural tumours that are not related to mesotheliomas. They are typically benign and pedunculated and may grow to massive sizes. Surgical resection is usually curative. Tumour recurrence and metachronous development of multiple tumours are unusual. In this report a patient was treated for 3 benign solitary fibrous tumours of the pleura over 23 years. The authors hypothesize that this represents multifocal tumorigenesis as opposed to local tumour recurrence. The importance of complete surgical excision and lifelong radiographic follow-up are stressed.


Histopathology 1998 May;32(5):423-32


Solitary fibrous tumour: significance of p53 and CD34 immunoreactivity in its malignant transformation.

Yokoi T, Tsuzuki T, Yatabe Y, Suzuki M, Kurumaya H, Koshikawa T, Kuhara H, Kuroda M, Nakamura N, Nakatani Y, Kakudo K Department of Pathology, Wakayama Medical College, Wakayama City, Japan.

AIMS: To clarify the association of p53 and CD34 expression with development of malignant solitary fibrous tumour we have studied 10 cases of solitary fibrous tumour arising in the pleura, retroperitoneum and pelvic cavity with clinicopathological features of malignancy. METHODS AND RESULTS: Tumours were localized solid masses with or without necrosis in eight and they nearly totally occupied the pleural cavity in two. Basic histology of the tumours was the proliferation of spindle cells arranged in 'patternless' pattern or in interlacing bundles with nuclear atypia and mitotic activities of various degree. In two, high-grade foci were present within low or intermediate-grade tumours. Recurrent tumours also showed more atypical features than primary tumours in two. Immunohistochemical studies showed CD34 positivity in seven, but three of them showed marked diminution or complete loss of CD34 expression in high-grade foci or a recurrent tumour. Three high-grade cases showed totally negative staining for CD34. p53 was strongly expressed in cases with fatal outcome, clinical recurrence, nuclear atypia, high mitotic activity or local invasion, whereas almost negative in benign tumours. CONCLUSIONS: Malignant solitary fibrous tumours may occur de novo or by transformation within benign or low-grade tumours and may be associated with p53 mutation. Although CD34 is a useful marker in the diagnosis of solitary fibrous tumour, one should bear in mind that its expression can be lost in high-grade tumours.


Kyobu Geka 1998 Jun;51(6):504-7

Malignant recurrence of solitary fibrous tumor of the pleura developed 20 years after the surgery: a case report of re-extirpation.

Ito H, Arai T, Niino H, Inagaki K, Morita T, Yano M, Nomura T Department of Thoracic Surgery, International Medical Center of Japan, Tokyo,Japan.

A 63-year-old female developed the chest wall tumor protruding into the right thoracic cavity. She consulted our hospital complaining of chest pain. 20 years before this episode, she had undergone tumor extirpation combined with the partial resection of adherent anterior chest wall and the diaphragm for large benign solitary fibrous tumor of the pleura. Because of the difficulty in making diagnosis by needle biopsy, operation (re-tumor extirpation combined with the chest wall) was done. Histological examination revealed that the tumor was malignant solitary fibrous tumor. We concluded that the tumor was the malignant recurrence of the benign solitary fibrous tumor resected 20 years before. Occasionally, benign solitary fibrous tumor of the pleura recurs and behaves more aggressively than primary, but such a long latent period as 20 years is quite uncommon. So we present the case and the review of the literature.


Ann Thorac Surg 1998 May;65(5):1461-4

Giant solitary fibrous tumor of the pleura.

Khan JH, Rahman SB, Clary-Macy C, Kerlan RK, George TI, Hall TS, Jablons DM Department of Thoracic Surgery, Mount Zion-UCSF Cancer Center 94115, USA.

Solitary fibrous tumors of the pleura are rare. Approximately 600 cases have been described in the literature. We report a case of a young man with a giant solitary fibrous tumor of the pleura that filled his entire left hemithorax and anterior mediastinum and extended into the right side of his chest. The diagnostic modalities employed, the operation, and the postoperative management resulting in complete resection of the tumor and full lung reexpansion are described.


Jpn J Clin Oncol 1998 Feb;28(2):86-91

Frequent expression of bcl-2 protein in solitary fibrous tumors.

Hasegawa T, Matsuno Y, Shimoda T, Hirohashi S, Hirose T, Sano T Pathology Division, National Cancer Center Research Institute, Tokyo, Japan.

The distinction of solitary fibrous tumors from histologically similar neoplasms is often difficult because they rarely occur at a variety of extrapleural sites. CD34 immunoreactivity has recently been recognized to be an adjunct for the diagnosis of solitary fibrous tumors. However, it is now known that CD34 staining is not entirely specific for this entity. We evaluated 23 solitary fibrous tumors and 54 other spindle cell tumors often considered in the differential diagnosis for immunoreactivity using monoclonal antibodies directed against bcl-2 protein, which protects cells from apoptosis and CD34. The patients with solitary fibrous tumors comprised 11 men and 12 women, ranging in age from 35 to 85 years (mean, 57.6 years). Fourteen tumors arose in the pleura, four in the retroperitoneum, three in the superficial soft tissue and one each in the mediastinum and uterine cervix. Nineteen of 23 solitary fibrous tumors (83%), irrespective of tumor site, demonstrated diffuse cytoplasmic staining for bcl-2 protein. bcl-2 immunoreactivity was also observed in five of seven neurofibromas (71%), eight of 10 synovial sarcomas (80%) and one of three spindle cell lipomas (33%). CD34 immunoreactivity was present in all but one solitary fibrous tumor (96%), seven of seven neurofibromas (100%), three of three spindle cell lipomas (100%), five of five dermatofibrosarcomas (100%), three of three hemangiopericytomas (100%) and two of seven malignant fibrous histiocytomas (29%). To date, most of the pleural and extrapleural cases have not shown aggressive features. We suggest that bcl-2 protein can be used together with CD34 in the diagnosis of solitary fibrous tumor to distinguish this entity from other spindle cell neoplasms.


Chest 1997 Nov 5;112(5):1424-8

Solitary fibrous tumor of the pleura: a report of five cases diagnosed by transthoracic cutting needle biopsy.

Weynand B, Noel H, Goncette L, Noirhomme P, Collard P Department of Pathology, Universite Catholique de Louvain, Cliniques Universitaires Saint-Luc, Brussels, Belgium.

Five patients had a solitary fibrous tumor of the pleura; a well-known but rare entity. In all cases, biopsy by a transthoracic cutting needle (Tru-Cut; Travenol; Deerfield, IL) yielded specimens adequate for histologic analysis and gave the clue to the diagnosis. In four patients, surgical resection confirmed the diagnosis. The opportunity for and interest in diagnosing these tumors by transthoracic cutting needle biopsy before surgery are discussed. An accurate diagnosis of solitary fibrous tumors of the pleura can be made by a minimally invasive procedure; this allows for a more informed allocation of surgical resources.

Cancer 1997 Apr 25;81(2):116-21


Solitary fibrous tumor. A cytologic-histologic study with clinical, radiologic, and immunohistochemical correlations.

Ali SZ, Hoon V, Hoda S, Heelan R, Zakowski MF Department of Pathology (Cytopathology), Johns Hopkins Hospital, Baltimore, Maryland, USA.

BACKGROUND: Solitary fibrous tumors (SFT) are rare neoplasms that most commonly involve the pleura, mediastinum, and lung. They are believed to be submesothelial in origin. Histologically, they are characterized by fibroblast-like cells and connective tissue in varying proportions. The "patternless pattern" and the hemangiopericytoma-like pattern are the most common arrangements. The majority of SFTs have been immunoreactive for CD34. Very little has been reported regarding the cytologic findings in these tumors. METHODS: The authors reviewed the radiographic findings and studied fine-needle aspiration biopsies performed on seven patients with SFT of the pleura, and examined subsequent histologic material. The cell blocks or smears of all cases were stained with a monoclonal antibody to CD34. RESULTS: The cytologic preparations showed varying degrees of cellularity. Smears were comprised of spindled cells in a bloody background with small amounts of collagen. The three malignant tumors had a greater number of cells, both dispersed and in clusters, with nuclear pleomorphism and prominent nucleoli. The cell blocks characteristically showed varying degrees of cellularity with thickened blood vessels and a hemangiopericytoma-like pattern. The cells from the four benign tumors tended to be smaller in size and grouped in more cohesive clusters than the malignant ones. CD34 stained the spindle tumor cells in the cell blocks or smears from five cases; one malignant and one benign case failed to stain. The corresponding histologic samples from these cases demonstrated the same CD34 staining pattern in all cases except one. CONCLUSIONS: The differential diagnosis of SFT includes neurogenic tumors, mesotheliomas, sarcomatoid carcinoma, synovial sarcoma, hemangiopericytoma, and fibrosarcoma. CD34, when present, may prove equally helpful as a positive marker in cytology and in histologic preparations in the differential diagnosis of SFT


Am J Clin Pathol 1996 Sep;106(3):325-31

Solitary fibrous tumor of the soft tissue. An immunohistochemical and ultrastructural study.

Hasegawa T, Hirose T, Seki K, Yang P, Sano T First Department of Pathology, University of Tokushima School of Medicine, Japan.

Solitary fibrous tumor is a rare spindle cell neoplasm of adults that usually arises in the pleura, recently reported in other locations. The authors describe three cases of solitary fibrous tumors in adults that occurred as circumscribed masses in the somatic soft tissue, including the arm, back, and abdomen. Histologically, they were characterized by a proliferation of spindle cells separated by thick bands of collagen and prominent vascularity often showing a hemangiopericytoma-like pattern. The spindle cells, having low mitotic figures and little nuclear atypicality, exhibited a variety of growth patterns, including storiform, fascicular and herringbone, and nuclear palisading. Vimentin and CD34 immunoreactivities were observed in many spindle cells of all tumors. They had ultrastructural features of fibroblast and myofibroblast in two cases examined. Solitary fibrous tumors seem to represent distinct mesenchymal neoplasms that require us to identify their unusual location other than the pleura and be familiar with their histologic appearances for arriving at the correct diagnosis.


Acta Chir Belg 1995 May-Jun;95(3):127-9

Solitary Fibrous Tumor Pleura.

Martens B, Bonnet P, Duquesne L Department of Vascular thoracic surgery, Centre hospitalier Soignies-Braine-le-Comte, Belgium.

The Solitary Fibrous Tumour of Pleura has rarely been observed. A new case has been reported. This tumour is often asymptomatic and mostly discovered by chance. A well delimited and round opacity is demonstrated on the chest X-ray. computerized tomography confirms the fleshy nature of this tumour with inhomogeneous enhancement. The treatment is a complete surgical excision. The prognosis is excellent, if diagnosed early.


Hum Pathol 1995 Apr;26(4):440-9


Solitary fibrous tumor: histological and immunohistochemical spectrum of benign and malignant variants presenting at different sites.

Hanau CA, Miettinen M Department of Pathology and Cell Biology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA 19107, USA.

Twenty-nine tumors (from 26 patients, including two with recurrent disease) diagnosed as solitary fibrous tumor (SFT) of the pleura (n = 23), mediastinum (n = 4), abdominal cavity (n = 1), and parotid gland (n = 1) were studied immunohistochemically. Three histologically malignant tumors showed areas of high cellularity and mitotic activity (more than 4 mitoses/10 high-power fields) with features resembling malignant fibrous histiocytoma, malignant hemangiopericytoma, or fibrosarcoma, together with areas typical of benign solitary fibrous tumor. Formaldehyde-fixed, paraffin-embedded tissues and avidin-biotin-complex immunostaining were used. All of the tumors showed vimentin positivity and did not stain for cytokeratin, glial fibrillary acidic protein, or muscle cell markers, except for focal desmin reactivity in seven tumors, mostly seen in frozen sections, and focal keratin reactivity in one histologically malignant tumor. The neoplastic cells were positive for CD34 and negative for CD31; these patterns also were seen in the three histologically malignant cases. In nine of the cases acetone-fixed frozen sections showed variable focal positivity for neurofilament proteins of 68 kd. We conclude that SFT is a neoplasm of fibroblasts/primitive mesenchymal cells with features of multidirectional differentiation. We also report the finding of a novel site for SFT, the parotid gland.


Hum Pathol 1995 Apr;26(4):428-31


CD-34 and keratin expression distinguishes solitary fibrous tumor (fibrous mesothelioma) of pleura from desmoplastic mesothelioma.

Flint A, Weiss SW Department of Pathology, University of Michigan School of Medicine, Ann Arbor, USA.

Solitary fibrous tumors (SFTs) often involve the pleura and also may encompass the peritoneum and nonserosal sites. On occasion SFTs mimics other neoplasms, including desmoplastic mesothelioma. CD-34, initially characterized as a hematopoietic progenitor cell antigen, recently has been identified in a small number of SFTs. Based on this observation, we compared the keratin, vimentin, and CD-34 expression of 19 SFTs and eight desmoplastic mesotheliomas. Fifteen of 19 SFTs (78.9%) expressed CD-34, whereas keratin expression was absent in all SFTs. In contrast, none of the desmoplastic mesotheliomas expressed CD-34 and keratin expression was found in seven of eight (87.5%). Vimentin expression was noted in 18 of 19 SFTs and in seven of eight desmoplastic mesotheliomas. We conclude that CD-34 expression distinguishes SFT from desmoplastic mesothelioma. Additionally, the results of our study support the idea that SFT is not derived from or related to conventional mesothelium.