XXXX of the orbit. Problems in the diagnosis and management of five cases.

@entity1 @entity2743 @entity75 @entity5 @entity6437 @entity243 @entity2694 @entity892 @entity1821
The clinicopathologic features and the results of diagnostic studies were reviewed in five @entity1 with primary @entity2694 . The major clinical complaints were @entity892 and proptosis; visual function was typically well maintained. In three cases, computed tomographic (CT) scans @entity75 with a central fat density rimmed by a variably radiodense pseudocapsule, leading to the erroneous clinical impression that the lesions were cystic in character. Ultrasonography ruled out a truly @entity5 by demonstrating internal acoustic interfaces. Magnetic resonance imaging (MRI) in one case showed hyperintense signals in T-1-weighted images, suggesting the presence of fat within the lesional tissue. In the other two cases, CT scans showed reticulated densities accentuating the septa of the orbital fat in the absence of clear-cut circumscription. A potentially useful feature pointing to a @entity5 was bowing of an involved extraocular muscle, which is usually straightened and splinted in either @entity2743 or @entity6437 . Histopathologically, two lesions were well-differentiated @entity1821 and three were @entity243 , all featuring univacuolar signet ring lipoblasts. Scattered bizarre hyperchromatic mesenchymal cells without prominent lipidization were present in the lesions. None of the @entity1 has experienced regional or distant metastases with follow-ups from onset of 1 to 7 years (mean, 5.2 years); three required orbital exenteration after local recurrence; and two who refused exenteration received only orbital radiotherapy.
