INTRODUCTION: Calcifying fibrous tumor (CFT) is an uncommon lesion that was first described in 1988 as a fibrous tumor of childhood and has been described in somatic soft tissue with pathologic features of densely collagenized fibrous tumor with psammomatous and dystrophic calcification accompanied by a lymphoplasmacytic infiltrate. CFT of the pleura is a very rare entity that was first described in 1996 and only 10 cases have been reported in the literature. We describe a case of multiple CFTs of the pleura in an asymptomatic 29-year-old female.
CASE PRESENTATION: A 29-year-old active duty USAF female was referred to our clinic for evaluation of multiple pulmonary masses of the right lower lung. Her past medical history was significant for PPD conversion when she was deployed to Korea five years prior to presentation. The patient was without pulmonary complaints or constitutional symptoms. Travel history was significant for military installations in the southeast U.S. and a one-year tour in Korea. A screening chest x-ray for the history of PPD conversion revealed multiple right lower lung masses; CT chest revealed multiple large right basilar calcified masses with the largest measuring 2.3 × 4.5 cm. A bone scan was unremarkable and alpha-fetal protein and beta-hCG were negative. A CT-guided biopsy showed hyalinized and calcified fibrous tissue with entrapped vascular structures without evidence of malignancy. The tissue was CD34 positive but Congo red, keratin, BCL-2 and S-100 stains were negative as well as tissue cultures. The patient subsequently had a surgical biopsy that revealed dense hyalinized collagen with scattered inflammatory cells and psammomatous calcifications consistent with calcifying fibrous tumor of the pleura. There was no evidence of extension into the surrounding lung.
DISCUSSIONS: Calcifying fibrous tumors (CFTs) are unusual tumors typically found in children and young adults. They have been reported to occur in subcutaneous and deep soft tissues of the extremities and trunk, groin, scrotum, mediastinum, myocardium, paratracheal region, peritoneum, neck, mesentery, omentum, serosa, lung, bone, and gallbladder. CFTs of the pleural are very rare and were first described in 1996 with 10 total cases reported in the literature to date. There are no specific clinical laboratory or imaging studies that distinguish CFT of the pleura from other intrathoracic lesions. The differential diagnosis includes metastasis from osteosarcoma, chondral harmatoma, fibrous tumor of pleura, calcified pleural plaques, calicified pleural metastsis and calcified granuloma. Previously described cases have required surgical diagnosis in 9 and CT-guided biopsy in one. The first report of CFT consisted of a series of 3 patients each with unencapsulated circumscribed masses of hyalinized collagenous fibrotic tissue interspersed with lymphoplasmacytic infiltrates and calcifications with psammomatous features. Lesions were limited to the pleura without extension into the lung parenchyma; multiple lesions are even more uncommon. Calcifying fibrous tumor of the pleura is distinct from other pleural lesions and was incorporated into the WHO classification of lung tumors as a distinct entity. Immunohistochemical staining has been reported to show spindle cells diffusely positive for vimentin, CD34, and negative for epithelial membrane antigen, keratin, smooth-muscle actin, desmin, S-100 protein and anaplastic lymphoma kinase-1. As with extrapleural lesions, treatment has consisted of local excision without reports of recurrence.
CONCLUSION: Calcifying fibrous tumor of the pleura is a rare tumor that can mimic other pleural lesions. Patients are asymptomatic with incidental pulmonary nodules or masses found on radiographic studies. Diagnosis requires surgical excision with histologic confirmation demonstrating densely collagenized fibrous tumor with psammomatous and dystrophic calcification accompanied by a lymphoplasmacytic infiltrate without extension into the lung parenchyma. Similar to extrapleural lesions, treatment with complete surgical excision appears to be curative.
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