CUSHINGS-SYNDROME FROM AN ECTOPIC PITUITARY-ADENOMA WITH PELIOSIS - AHISTOLOGICAL, IMMUNOHISTOCHEMICAL, AND ULTRASTRUCTURAL-STUDY AND REVIEW OF THE LITERATURE

Ectopic pituitary adenoma (EPA) is rare and, to the authors' knowledge , its association with peliosis has not yet been described. The case o f a 38-yr-old woman with clinical and biochemical evidence of Gushing' s syndrome is reported. Magnetic resonance imaging (MRI) disclosed a n ormal pituitary and a separate mass in the sphenoid sinus. The surgica lly removed portion of the sellar pituitary contained no adenoma. Ther e was only Crooke's hyaline change in the corticotrophs, indicating ex posure to glucocorticoid excess. By histology, the mass in the sphenoi d sinus was a congested, chromophobic, partly basophilic, periodic aci d-Schiff (PAS)-positive pituitary adenoma composed of pleomorphic, adr enocorticotropic hormone (ACTH)-positive, corticotrophs. There was foc al immunopositivity for MIB-1 and proliferating cell nuclear antigen ( PCNA). Electron microscopy confirmed the diagnosis of corticotroph ade noma. A striking finding, consistent with the diagnosis of peliosis, w as the presence of multiple large blood-filled spaces lacking an endot helial lining. The capillaries were dilated, but often appeared empty and the fenestrated endothelium exhibited discontinuities. The ca use of peliosis is obscure. It may be that the venous outflow was impaired in this case leading to capillary dilation, congestion, hyperpermeabi lity, rupture, and accumulation of blood in extravascular spaces.