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A3218 - Pleural Lipoma with Secondary Changes - A Diagnostic Challenge
Author Block: J. Akhtar1, A. Lal1, K. B. Martin2; 1Internal Medicine, Saint Vincent Hospital, Worcester, MA, United States, 2Pulmonary, Reliant Medical Group, Worcester, MA, United States.
Introduction: Lipoma is a benign soft tissue tumour, which originates from adipose tissue. It is mostly found within the subcutaneous areas of the body. Intrathoracic lipomas are rare, usually located at the mediastinal, bronchial and pulmonary levels. A pleural lipoma is a extremely rare clinical entity. Most patients remain asymptomatic. A pleural lipoma is discovered incidentally on a chest radiograph. The diagnosis is usually established by computed tomography. We are presenting a case of pleural lipoma, which highlights the importance of histopathological diagnosis for lipoma. Case report: A 72 yr old male presented with complain of shortness of breath and cough , found to have pleural based mass in left lung on chest X ray. CT chest revealed smooth pleural based mass with homogenous fat density along posterolateral aspect of apical left hemithorax ,diagnosed as lipoma. His subsequent follow up CT chest showed increase in size and mixed attenuation. There was macroscopic fat as well as soft tissue density on CT. Rim calcification was noted. There was a concern for liposarcoma, so left pleural mass was surgically resected. Gross examination of resected pleural mass revealed well-circumscribed, dense white fibrotic cystic structure, filled with gelatinous variegated red-brown to tan-yellow material (4.5 x 3.5 x 2.5 cm). Histopathological examination revealed fibrous walled cyst with dense fibrosis and dystrophic calcification attached to the pleural surface of the lung. Much of the cyst was lined by histiocytes with occasional multinucleated giant cells. The cyst was largely filled with organizing blood clot and hemosiderin deposits were also noted in the cyst wall. A few foci with acute inflammation and histocytes consistent with residual abscess cavity were present within the larger cyst. No fat cells or malignant cells were identified in the multiple sections examined. Discussion: The diagnosis of pleural lipoma is usually made by CT chest. The diagnostic criteria on CT are: presence of a well-defined mass composed of homogeneous fat attenuation (−50 to −150 HU), not enhanced by an injected contrast medium, having obtuse angles with the chest wall and displacing adjacent pulmonary parenchyma and vessels. Biopsy of the tumor remains the gold standard for diagnosis, but they are generally recommended for lesions that are inhomogenous, containing mixed fatty and soft tissue components. Pleural lipomas may have complications such as intratumoral haemorrhage, fat necrosis and chronic inflammation. Due to these complications, biopsy may be frequently nondiagnostic, as in our case.