A finding of a growth in the head can be a deeply unsettling experience. The Rathke Cleft Cyst (RCC) is a generally rare lesion often discovered unintentionally during imaging procedures performed for other reasons. Understanding what this specific type of cyst is, and what it is not, can help alleviate anxiety associated with brain-related diagnoses.
Defining the Rathke Cleft Cyst
The Rathke Cleft Cyst is a fluid-filled sac originating from Rathke’s pouch, a remnant of embryonic development. This pouch is an extension of the primitive oral cavity that normally forms the pituitary gland. A small cleft can sometimes persist between the anterior and posterior lobes of the pituitary gland.
The cyst forms when this persistent remnant fills with a watery, gelatinous, or mucus-like fluid. This structure is located within the sella turcica, a small, bony compartment at the base of the skull housing the pituitary gland. The cyst is lined by epithelial cells that secrete the mucoid material, causing the sac to gradually expand.
Understanding Why It Is Not a Brain Tumor
A Rathke Cleft Cyst is classified as a non-neoplastic lesion, meaning it is not a brain tumor. The fundamental difference lies in its origin and the behavior of the cells. A true brain tumor, or neoplasm, involves the uncontrolled proliferation of cells, leading to a growing mass of new tissue.
In contrast, an RCC is a congenital malformation resulting from an incomplete involution of the embryonic Rathke’s pouch. The cyst wall is composed of non-proliferative epithelial cells that do not multiply abnormally to form a solid mass. Instead, the growth of the RCC is due to the slow accumulation of secretory fluid within the closed sac, distinguishing it from a cancerous or benign tumor like a pituitary adenoma.
Symptoms and Diagnostic Imaging
Most Rathke Cleft Cysts are small and asymptomatic, leading to their incidental discovery on a magnetic resonance imaging (MRI) scan. When symptoms occur, they result from the cyst growing large enough to exert pressure on nearby structures. Diagnosis is primarily achieved through MRI, which provides detailed images of the cyst’s location and fluid content, helping to distinguish it from other masses.
If the cyst extends upward, it can compress the optic chiasm, leading to visual disturbances, often resulting in a loss of peripheral vision. Compression of the pituitary gland itself can also impair its function, causing hormonal imbalances. These symptoms may include:
- Headaches, often caused by increased pressure within the sella turcica.
- Visual disturbances, such as loss of peripheral vision.
- Fatigue or irregular menstrual cycles.
- Issues with growth and puberty in younger patients.
Management and Treatment Options
Management is determined by the presence and severity of symptoms. For cysts found incidentally that are not causing issues, the typical approach is watchful waiting, involving periodic monitoring with MRI scans. This conservative strategy is appropriate because most asymptomatic cysts do not grow significantly over time.
If the cyst is symptomatic, especially if it causes visual impairment or severe hormonal dysfunction, surgical intervention is generally recommended. The most common method is the transsphenoidal approach, a minimally invasive procedure performed through the nose and sphenoid sinus. The goal is to drain the cyst’s contents and remove a portion of the wall to prevent recurrence. While surgery often resolves symptoms, recurrence is possible, requiring long-term follow-up.