Persistence of intrasellar trigeminal artery and simultaneous pituitary adenoma: description of two cases and their importance for the differential diagnosis of sellar lesions.

Persistent trigeminal artery (PTA) is the most frequent embryonic communication between the carotid and vertebrobasilar systems. However, hormonal changes or the association of PTA with other sellar lesions, such as pituitary adenomas, are extremely rare. The aim of the present study was to report two patients with intrasellar PTA and simultaneous pituitary adenoma in order to emphasize the importance of differential diagnoses for sellar lesions. Case 1. A female patient, 41 years old, was admitted with a history of chronic headache (> 20 years). Pituitary magnetic resonance imaging (MRI) showed a rounded lesion in the left portion of the pituitary gland suggestive of adenoma (most likely clinically non-functioning adenoma). In addition to this lesion, the MRI demonstrated ecstasy of the right internal carotid artery and imaging suggestive of an intrasellar artery that was subsequently confirmed by an angio-MRI of the cerebral vessels as PTA. Case 2. A female patient, 42 years old, was admitted with a history of amenorrhea and galactorrhea in 1994. Laboratorial investigation revealed hyperprolactinemia. Pituitary MRI showed a small hyposignal area in the anterior portion of pituitary gland suggestive of a microadenoma initiated by a dopaminergic agonist. Upon follow-up, aside from the first lesion, the MRI showed a well delineated rounded lesion inside the pituitary gland, similar to a vessel. Angio-MRI confirmed a left primitive PTA. Failure to recognize these anomalous vessels within the sella might lead to serious complications during transsphenoidal surgery. Therefore, although their occurrence is uncommon, a working knowledge of vascular lesions in the sella turcica or pituitary gland is important for the differential diagnosis of pituitary lesions, especially pituitary adenomas.