Epidermoid Cyst of the Pituitary Stalk : Case Report and Review of the Literature

Objective and Importance: Epidermoid cysts are fairly uncommon lesions that have a maldevelopmental origin and are thought to arise from trapped surface ectodermal elements. These cysts are usually located in the subarachnoid spaces, typically in the cerebellopontine angle. Many unusual locations have been reported; however, to our knowledge this is the first described case of an epidermoid cyst arising in the pituitary stalk. Clinical Presentation: The patient is a 27-year-old woman with a 2-year history of amenorrhea, galactorrhea, and secondary polyuria and polydipsia. A preoperative magnetic resonance imaging study showed a lesion extending from the upper part of the sella to the suprasellar region (up to the chiasm) with in-homogenous signals in both T1 and T2 images. Intervention: The cyst was partially resected through an endonasal trans-sphenoidal extended endoscopic approach by a multidisciplinary team [neurosurgeons and ear nose throat (ENT) surgeons]. The postoperative course was uneventful. The histologic examination disclosed a squamous epithelium and the presence of dry keratinous debris, establishing the epidermoid nature of the lesion. Conclusions: Surgical removal is the treatment of choice of symptomatic epidermoid cysts. In this unusual presentation (intrasellar/suprasellar) the authors preferred an endonasal trans-sphenoidal extended endoscopic approach. However, as in almost every case of epidermoid cyst, the adherence between the capsule of the lesion and neurovascular structures made complete removal of the cyst walls impossible.