Intra-sellar Salivary Gland-like Pleomorphic Adenoma Arising within Wall of a Rathke's Cleft Cyst

Abstract

Salivary gland rests occur in the posterior lobe of the pituitary gland near or often communicating with the Rathke's cleft or its cystic subdivisions, and are usually incidental autopsy findings. They are attributed to the oropharyngeal development of the Rathke's pouch and may rarely give rise to salivary gland-like tumors in the sella. We present a pleomorphic adenoma, a rare tumor of the sellar region, that has not been previously recognized in association with Rathke's cleft cyst. It occurred in a 44-year-old man who presented with hypopituitarism and reduced vision. Magnetic resonance imaging showed a sellar mass with suprasellar extension which was totally removed. It consisted of segments of a cyst wall lined by focally ciliated columnar of cuboid epithelium containing goblet cells. An eosinophilic granular material with cholesterol clefts represented the contents of the cyst. Within its wall there was a tumor with ductal structures and non-ductal varied cellular components including hypercellular areas of spindle and ovoid cells forming interlacing fascicles. Individual cells appeared to float in abundant mucinous material. The appearances were those of a salivary gland pleomorphic adenoma arising within the wall of a Rathke's cleft cyst. The myoepithelial nature of non-ductal tumor cells was confirmed with immunocytochemistry. The existence of seromucous glands communicating with the Rathke's cleft remnants, explains the concomitant occurrence of the tumor and the cyst. This rare neoplasm from salivary gland rest should be considered in the differential diagnosis of unusual sellar and suprasellar tumors.