What is Rathke’s Cleft Cyst?
Rathke’s cleft cysts (RCC) are benign, non-cancerous lesions. They are often found by chance on MRI scans done for other reasons (incidental finding) and can be seen in approximately 20% of unselected post-mortem examinations.
Rathke’s cysts are rare and can occur at any age but are more commonly found in adults.
Lesions within the pituitary gland or sellar region (the area where the pituitary gland sits) are typically either solid, cystic or a combination of both.
Cysts (or cystic lesions) are fluid filled structures, with contents that can be “water-like” or thick (often described as proteinaceous). Pituitary tumours are more typically solid in nature although cystic pituitary tumours are not uncommon.
Symptoms
Small RCCs are unlikely to cause any symptoms, however, larger lesions can cause symptoms.
Headaches
Evidence shows that headaches are a common feature (about 60%) in RCCs that need surgical intervention. However, there is not enough evidence on whether small RCCs cause headaches.
Loss of hormonal function
This occurs if the RCC becomes large enough to compress the pituitary gland or stalk. You may develop hypopituitarism as the pituitary gland will not be producing enough of some or all of its normal signalling hormones. This can lead to issues with fatigue, loss of energy, weight gain, poor concentration and an inability of the body to react appropriately to stress and illness.
If the pituitary stalk is compressed there will be a modest rise in prolactin secretion which may lead to amenorrhoea (loss of periods), galactorrhoea (breast discharge) or loss of libido and erectile function.
Visual Dysfunction
If RCCs grow upwards they will eventually compress the optic nerves and chiasm (nerves responsible for vision) in a similar fashion to a large pituitary tumour. Initially, people might notice that their vision is a little dulled, commonly affecting the colour red, and then will start to lose their peripheral vision.
Peripheral visual loss is not easily noticed and usually starts with loss of the upper outer region (outer superior quadrantanopia). As the cyst becomes larger, people will lose the lower aspect too and develop a bitemporal hemianopia (losing the right half of the vision from the right eye and the left half of the vision from the left eye).
If the compression continues to progress then the visual acuity (ability to see or read the eye charts) will also deteriorate.
Treatment
Anyone diagnosed with a Rathke’s cleft cyst should be referred to the local Pituitary Multidisciplinary Team for further discussion. If you have small incidental RCCs may be managed without any intervention. Formal endocrinological and visual assessment to provide a baseline assessment for patients with larger RCCs is likely to be the first step in management.
If there is endocrine dysfunction, then hormonal replacement directed by a pituitary endocrinologist, as with any other pituitary or sellar based lesion, should be started.
If you are asymptomatic or if your symptoms are able to be managed with medical treatments, conservative management with regular endocrine, then visual and radiological surveillance, usually with MRI scans, would be appropriate.
In the presence of a visual field or acuity loss secondary to RCC, surgery would be the treatment of choice. Trans-sphenoidal surgery (via the nose and sphenoid sinus) is the most common approach for RCCs. Very rarely, the RCC may need trans-cranial (open surgery through the head) surgery.
Headaches that are not responding to medical management may also be an indication for surgery.
Surgery is aimed at excising the RCC, although sometimes all the lining of the cyst cannot easily be removed and therefore removal of the contents of the cyst and as much of the lining that can be safely excised is carried out.
After surgery over 75% of people experience visual improvement and two-thirds have an improvement in headaches.
Surgery Risks
The risks from surgery are similar to operating on people with a pituitary tumour. Surgery is performed under a general anaesthetic. The specific risks from the surgical approach include risks of infection, bleeding, CSF leak, meningitis, loss of sense of smell, worsening vision, further hormonal dysfunction, stroke and a small risk to life. Having any operation under general anaesthetic can lead to risks that include post-operative chest infection, deep venous thrombosis (clot in the legs), pulmonary embolus (clot in the lungs) or a heart attack.
Regular Scans
Despite surgery, RCCs have a significant rate of recurrence with up to 40% seen on long-term follow-up scans although most did not need any further intervention. People who have small incidental RCCs there is no benefit in regular MRI scans unless there are new symptoms or concerns.
In those that are being actively managed conservatively, annual surveillance MR imaging to look for any changes in the size of the cyst would be part of management. If the RCC remains stable then increasing the intervals between scans would be safe to do so as long as there are no new symptoms.
Even after surgery there is a longer-term risk of recurrence and therefore post-operative surveillance imaging would be recommended. MRI scanning initially 6 months post-operatively, followed by annual scans and then at increased intervals, if there were no concerns, would be a common follow-up strategy.
