Occurring with one tenth the frequency of epidermoid cysts, dermoid cysts are rare. Given their affinity for midline intracranial sites, their occasional occurrence in the sellar and parasellar regions is well recognized, although published
reports of such cases have been few (133). In addition to the epidermal elements present in epidermoid cysts, dermoid cysts have the additional features of hair follicles, sweat glands, and sebaceous glands. These lesions typically have a firm fibrous capsule that is often densely adherent to surrounding structures.
Dermoid cysts occur in younger patients, with most cases occurring within the first two decades of life. Their clinical presentation in the sellar region is variable, and DI, visual dysfunction, precocious puberty, and mild hyperprolactinemia have all been associated with dermoid cysts in this area. Some are confined exclusively to the sella, others are exclusively suprasellar, and some involve both sites. Radiologically, dermoid cysts appear as inhomogeneously enhancing masses, sometimes calcified, and often containing fat.
Like epidermoid cysts, dermoid cysts are also prone to spontaneous bouts of chemical meningitis caused by seepage of their irritative cyst contents into the CSF, and they too may, rarely, undergo malignant transformation to squamous cell carcinoma (134). As a rule, dermoid cysts grow more quickly than epider-moid cysts and recur more frequently.
Therapy for parasellar dermoid cysts is surgical removal. Although complete surgical excision of these lesions is always desirable, their frequent adherence to cranial nerves and blood vessels often necessitates a safer subtotal resection. Postoperative radiotherapy has not shown any benefit in either shrinking residual tumor or forestalling recurrence, and as such is not recommended. Fortunately, subtotal resection alone usually provides long-term symptom-free survival.
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