대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Localized fibrous tumor of the pleura

Radiologic Findings

The patient was admitted due to epigastric pain for 7 days and had a history of gallstones detected on ultrasonography. Chest abnormality was incidentally detected. Chest radiograph shows huge well-defined homogeneous mass in left upper lobe, which is broadly based on left pleura and is sharply demarcated by left interlobar fissure on lateral view. CT scans show a well-defined soft tissue mass with moderate heterogeneous enhancement. Left upper lobe is compressed by the tumor. Low attenuating area within the mass suggests cystic degeneration or hemorrhage. US-guided gun biopsy was performed. Histologically, the lesion was localized fibrous tumor of the pleura without definite pleomorphism and mitosis.

Brief Review

Localized fibrous tumors are rare mesenchymal neoplasms that most commonly affect the pleura but have also been described in a number of other locations including the mediastinum and the lung. Extrathoracic localized fibrous tumors have been reported in the abdomen, the head and neck, and the central nervous system.

Many names have been used to designate this neoplasm in the literature; localized fibrous tumor of the pleura, benign fibrous mesothelioma, benign fibrous tumor of the pleura. Clinically localized fibrous tumor of the pleura(LFTP) occurs in both sexes and in all age groups but predominantly affects persons more than 50 years old. Most patients are asymptomatic; cough, chest pain, and dyspnea occur occasionally, especially in association with large tumors. Extrathoracic manifestations include hypertrophic osteoarthropathy in 4-35% and hypoglycemia. Hypoglycemia, noted in less than 5% of patients, is usually associated with very large tumor and is thought to be due to glucose consumption by the mass.

Radiologically, a small to medium-sized tumor appears as a solitary, sharply delineated, often lobulated nodule or mass of variable size from 1 to 39 cm, and forms obtuse angle with the chest wall. Large tumors can appear as opacification of a portion of one hemithorax, and often forms acute angle with the chest wall as the mass is pedunculated or becomes larger than the pleural origin. LFTP exist in the costal compartement of pleura, within an interlobar fissure, along pleural surface of mediastinum, along the diaphragmatic pleura and rarely within the lung parenchyma. These tumors predominate in the middle and lower half of the chest. A pedunculated LFTP can change position and appearance with respiration or with a change in position. Calcification has been reported in 7% of tumors. pleural effusion was present in 8-17% of cases but is more likely to be associated with malignant tumors than the benign.

On CT scans, LFTPs are well-delineated, often lobulated soft-tissue attenuation mass in close relation to the pleural surface or fissure, and absence of chest wall invasion. Calcifications are noted in large tumors and related to the areas of necrosis. The tumors have rich vascularization and shows intense and homogeneous enhancement. Nonenhancing areas on CT scans correspond to necrosis, myxoid degeneration, or hemorrhage within the tumor. Identification of pedicle is a clue to the diagnosis. CT findings that suggest a malignant fibrous tumor include a diameter larger than 10cm, central necrosis, and ipsilateral pleural effusion.

MRI is superior to CT for the morphology of a tumor, the relationships of the tumor to adjacent structures and, characterization of tissue. Tumors are intermediate to low signal intensity on T1-weighted images and of low signal intensity on proton density-weighted and T2-weighted images, which is related to hypocellularity and abundant collagen stroma. Areas of high signal intensity on T2-weighted images are related to areas of necrosis or myxoid degeneration. Intense enhancement has been reported after injection of gadolinium.

The differential diagnosis includes solitary pleural metastasis, pleural lipoma, pleural fibrosarcoma, intercostal nerve neurilemoma, organized inflammation, and most important, peripheral bronchogenic carcinoma.

References

1. Rosado ML, Abbott GF, McAdams HP, Franks TJ, Galvin JR. Localized fibrous tumors of the pleura. Radiographics 2003;23:759-783.

2. Ferretti GR, Chiles C, Choplin RH, Coulomb M. Localized benign fibrous tumor of the pleura. AJR 1997;169:683-686.

3. Muller NL. Imaging of the pleura. Radiology 1993;186:297-309.

4. Desser TS, Stark P. Pictorial essay: Solitary fibrous tumor of the pleura. Journal of Thoracic imaging 1998;13::27-35.

5. Ferretti GR, Chiles C, Cox JE, Choplin RH, Coulomb M. Localized benign fibrous tumors of the pleura: MR appearance. JCAT 1997;21:115-120.

Keywords

Pleura, Benign tumor,