Solitary Fibrous Tumor of the Pleura

Background

This rare tumor is most frequently diagnosed as an incidental finding on a routine chest x-ray or for evaluation of an unrelated disease. These tumors usually arise from the visceral pleura with a lesser percentage (about 20-40%) arising from the parietal pleura. In cases which are symptomatic, patients present with cough, chest pain, and shortness of breath (dyspnea). If hemoptysis occurs, a malignant tumor should be suspected. The benign tumors are slow growing and compress adjacent structures but usually do not invade. On microscopic sections, the pattern has been described as a mixture of spindle cell patterns, sometimes a patternless pattern. All of the tumors are united by a common staining pattern for the CD34 immunoperoxidase stain. This pattern may be found in similar tumors which have been reported in nearly every organ and location and have been termed solitary fibrous tumors. Although malignant tumors may occur, benign tumors are far more common outnumbering the malignant tumors by a ratio of 4 to 1.

SYNONYMS Solitary fibrous tumor of the pleura

INCIDENCE
Rare
2.8/100,000 patient admissions at the Mayo Clinic

AGE RANGE-MEDIAN
6-7th decades peak
Range 5-87 years

SEX (M:F)
Equal

EPIDEMIOLOGIC ASSOCIATIONS CHARACTERIZATION

Asbestos exposure Possible association

GROSS APPEARANCE/CLINICAL VARIANTS CHARACTERIZATION

General
Tumor may be pedunculated and connected to the pleura surface by a fibrous band

Cut surface is white and whorled with occasional foci of hemorrhage

VARIANTS

HISTOLOGICAL TYPES CHARACTERIZATION

GENERAL Two predominant patterns have been described but may coexist

VARIANTS

DIFFUSE SCLEROSING Extensive fibrous stroma

SOLID SPINDLE CELL

MALIGNANT TUMORS Malignant tumors have greater cellularity with an infiltrative growth pattern, variation in nuclear size and shape, prominent nucleoli, and increase in mitotic activity to usually >4/10 hpf

Malignant Solitary Fibrous Tumor of the Pleura With Liposarcomatous Differentiation
Arch Pathol Lab Med 2001;125:406�409

66-year-old, white man with a large, solid right pleural mass that measured 13.5 � 10.3 � 8.5 cm

Numerous adipocytes mixed with typical lipoblasts were seen scattered throughout portions of the tumor
Immunohistochemistry revealed the tumor cells were strongly positive for CD34 and vimentin and negative for cytokeratin, desmin, smooth muscle actin (IA4), and S100

SPECIAL STAINS/IMMUNOPEROXIDASE/OTHER CHARACTERIZATION

Special stains

Immunoperoxidase CD34 positivity is the hallmark-ranges from 80-100% of cases
Present in both benign and malignant tumors

CD99
Positive in the majority of tumors but only rarely in sarcomatoid mesotheliomas

bcl-2
Positive in both pleural and non-pleural tumors but not in mesotheliomas

Vimentin
Positive

DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES

Spindle cell mesothelioma

Biphasic or monophasic synovial sarcomas

Smooth muscle tumors

Sarcomatoid carcinoma

PROGNOSIS AND TREATMENT CHARACTERIZATION

PROGNOSIS May have an unpredictable course

Pedunculated tumors
May have better prognosis

Evidence of invasion of lung parenchyma, chest wall or diaphragm
Poor prognosis

Significant cellular atypia, increased mitotic activity, extensive necrosis
Poor prognosis

Recurrence Local recurrence has been reported as long as 17 years after initial complete resection

TREATMENT
Complete resectability is most important determinant of survival

More radical surgical may be needed for malignant tumors

Ann Thorac Surg 1000;67:1456-1459
Post-operative radiotherapy and/or chemotherapy

SURGERY

Solitary fibrous tumour of the pleura: surgical treatment.

Rena O, Filosso PL, Papalia E, Molinatti M, Di Marzio P, Maggi G, Oliaro A.

Department of Thoracic Surgery, S. Giovanni Battista Hospital, University of Torino, v. Genova 3, 10126 Torino, Italy.

Eur J Cardiothorac Surg 2001 Feb;19(2):185-9 Abstract quote

OBJECTIVE: Solitary fibrous tumours (SFT) of the pleura are rare tumours originated from the mesenchimal tissue underlying the mesothelial layer of the pleura. This tumours present unpredictable clinical course probably related to their histological and morphological characteristics.

METHODS: Twenty-one patients affected by SFT of the pleura were referred to us for surgical resection from September 1984 to April 2000. They were 15 males and six females with median age of 51 (range 15--73) years. Nine patients (43%) were symptomatic and predominant clinical symptoms or signs were dyspnoea (19%), coughing (14.3%), chest pain (28.5%), finger clubbing (14.3%) and hypoglycaemia (14.3%). Hypoglycaemia was related to a pathological incretion of insulin-like growth factor 2 by the tumour. Chest radiograph and computed tomography of the chest revealed intra-thoracic homogeneous sharply delineated round or lobulated mass sometimes associated with ipsilateral pleural effusion (19%) or causing pulmonary atelectasis with opacification of the complete hemithorax (19%). Surgical excision required 14 posterolateral thoracotomies, six anterior thoracotomies and one video-assisted thoracoscopy. Thirteen tumours arose from visceral pleura and wedge resection was performed, seven tumours arose from parietal pleura and extrapleural resection was carried out without any chest-wall resection, one tumour growth within the upper left lobe and required lobectomy. Tumours weighted from 22 to 1942 g and measured from 22x12x8 to 330x280x190 mm. At cut section seven cases (34%) revealed focal necrosis and hemorrhagic zones and on light microscopy six cases (28.5%) were characterized by high mitotic count: characteristics related with uncertain clinical behaviour. Immuno-histochemical reactions were in all cases positive for CD34.

RESULTS: In all our patients resections were complete. Paraneoplastic syndromes like hypoglycaemia and clubbing receded after surgery. No intraoperative or perioperative medical or surgical complications occurred. Median chest-drain duration timed 3 (range 2--5) days and median hospital stay was 5 (range 4--7) days. Perioperative mortality rate was 0%. Median follow-up was 68 (range 2--189) months: during this period patients were submitted to chest X-ray with 6-months interval to evaluate possible local recurrence. Only one patient experienced tumour recurrence after 124 months follow-up: the tumour was suspected after observation of finger clubbing. The tumour was detected and excised by redo-thoracotomy.

CONCLUSIONS: Surgical resection of benign solitary fibrous tumours is usually curative, but local recurrences can occur years after seemingly adequate surgical treatment. Malignant solitary fibrous tumours generally have a poor prognosis. Clinical follow-up and radiological follow-up are indicated for both benign and malignant solitary fibrous tumours.

Adv Anat Pathol 2000;7:327-340.

Commonly Used Terms

Lung

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Last Updated 11/22/2001

SYNONYMS	Solitary fibrous tumor of the pleura
INCIDENCE	Rare 2.8/100,000 patient admissions at the Mayo Clinic
AGE RANGE-MEDIAN	6-7th decades peak Range 5-87 years
SEX (M:F)	Equal

EPIDEMIOLOGIC ASSOCIATIONS	CHARACTERIZATION
Asbestos exposure	Possible association

HISTOLOGICAL TYPES	CHARACTERIZATION
GENERAL	Two predominant patterns have been described but may coexist
VARIANTS
DIFFUSE SCLEROSING	Extensive fibrous stroma
SOLID SPINDLE CELL
MALIGNANT TUMORS	Malignant tumors have greater cellularity with an infiltrative growth pattern, variation in nuclear size and shape, prominent nucleoli, and increase in mitotic activity to usually >4/10 hpf
Malignant Solitary Fibrous Tumor of the Pleura With Liposarcomatous Differentiation	Arch Pathol Lab Med 2001;125:406�409 66-year-old, white man with a large, solid right pleural mass that measured 13.5 � 10.3 � 8.5 cm Numerous adipocytes mixed with typical lipoblasts were seen scattered throughout portions of the tumor Immunohistochemistry revealed the tumor cells were strongly positive for CD34 and vimentin and negative for cytokeratin, desmin, smooth muscle actin (IA4), and S100

SPECIAL STAINS/IMMUNOPEROXIDASE/OTHER	CHARACTERIZATION
Special stains
Immunoperoxidase	CD34 positivity is the hallmark-ranges from 80-100% of cases Present in both benign and malignant tumors
CD99	Positive in the majority of tumors but only rarely in sarcomatoid mesotheliomas
bcl-2	Positive in both pleural and non-pleural tumors but not in mesotheliomas
Vimentin	Positive

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
Spindle cell mesothelioma
Biphasic or monophasic synovial sarcomas
Smooth muscle tumors
Sarcomatoid carcinoma

PROGNOSIS AND TREATMENT	CHARACTERIZATION
PROGNOSIS	May have an unpredictable course
Pedunculated tumors	May have better prognosis
Evidence of invasion of lung parenchyma, chest wall or diaphragm	Poor prognosis
Significant cellular atypia, increased mitotic activity, extensive necrosis	Poor prognosis
Recurrence	Local recurrence has been reported as long as 17 years after initial complete resection
TREATMENT	Complete resectability is most important determinant of survival More radical surgical may be needed for malignant tumors
	Ann Thorac Surg 1000;67:1456-1459 Post-operative radiotherapy and/or chemotherapy
SURGERY
Solitary fibrous tumour of the pleura: surgical treatment. Rena O, Filosso PL, Papalia E, Molinatti M, Di Marzio P, Maggi G, Oliaro A. Department of Thoracic Surgery, S. Giovanni Battista Hospital, University of Torino, v. Genova 3, 10126 Torino, Italy.	Eur J Cardiothorac Surg 2001 Feb;19(2):185-9 Abstract quote OBJECTIVE: Solitary fibrous tumours (SFT) of the pleura are rare tumours originated from the mesenchimal tissue underlying the mesothelial layer of the pleura. This tumours present unpredictable clinical course probably related to their histological and morphological characteristics. METHODS: Twenty-one patients affected by SFT of the pleura were referred to us for surgical resection from September 1984 to April 2000. They were 15 males and six females with median age of 51 (range 15--73) years. Nine patients (43%) were symptomatic and predominant clinical symptoms or signs were dyspnoea (19%), coughing (14.3%), chest pain (28.5%), finger clubbing (14.3%) and hypoglycaemia (14.3%). Hypoglycaemia was related to a pathological incretion of insulin-like growth factor 2 by the tumour. Chest radiograph and computed tomography of the chest revealed intra-thoracic homogeneous sharply delineated round or lobulated mass sometimes associated with ipsilateral pleural effusion (19%) or causing pulmonary atelectasis with opacification of the complete hemithorax (19%). Surgical excision required 14 posterolateral thoracotomies, six anterior thoracotomies and one video-assisted thoracoscopy. Thirteen tumours arose from visceral pleura and wedge resection was performed, seven tumours arose from parietal pleura and extrapleural resection was carried out without any chest-wall resection, one tumour growth within the upper left lobe and required lobectomy. Tumours weighted from 22 to 1942 g and measured from 22x12x8 to 330x280x190 mm. At cut section seven cases (34%) revealed focal necrosis and hemorrhagic zones and on light microscopy six cases (28.5%) were characterized by high mitotic count: characteristics related with uncertain clinical behaviour. Immuno-histochemical reactions were in all cases positive for CD34. RESULTS: In all our patients resections were complete. Paraneoplastic syndromes like hypoglycaemia and clubbing receded after surgery. No intraoperative or perioperative medical or surgical complications occurred. Median chest-drain duration timed 3 (range 2--5) days and median hospital stay was 5 (range 4--7) days. Perioperative mortality rate was 0%. Median follow-up was 68 (range 2--189) months: during this period patients were submitted to chest X-ray with 6-months interval to evaluate possible local recurrence. Only one patient experienced tumour recurrence after 124 months follow-up: the tumour was suspected after observation of finger clubbing. The tumour was detected and excised by redo-thoracotomy. CONCLUSIONS: Surgical resection of benign solitary fibrous tumours is usually curative, but local recurrences can occur years after seemingly adequate surgical treatment. Malignant solitary fibrous tumours generally have a poor prognosis. Clinical follow-up and radiological follow-up are indicated for both benign and malignant solitary fibrous tumours.