Detailed interpretation: Ratheke cyst

case

Patient, female, 32 years old

Chief Complaint: Dizziness, headache for more than two months

MRI scan plus enhanced scan on admission

Clinical diagnosis: MRI findings of sellar space-occupying lesions

The sella is not large, the bottom of the sella is slightly depressed, and abnormal cystic signal shadows can be seen between the anterior and posterior pituitary lobes.
The signal is slightly high on T1WI and equal and slightly low on T2WI.
The enhanced scan shows mild enhancement, the pituitary stalk is not clear, and the optic chiasm is unclear.
Lift slightly
.

surgical record

The patient was admitted to the operating room, under general anesthesia, the outer septal mucosa was incised, the nasal septum cartilage was separated, and the bony nasal septum was freed subperiostally to the bottom of the sphenoid sinus.
The sinus floor mucosa was exposed, the sellar floor was bitten out, the sellar floor bone was removed, the sellar floor dura was electrocauterized, and a cross incision was made.
The tumor tissue in the sella was seen to flow out.
The tumor was soft, jelly-like, and contained wax-like substances.
The tumor was completely excised under the microscope, and part of it was sucked away by the suction device.
It was found that the septum was well collapsed.
The bottom of the saddle was sealed with gelatin sponge.
No active bleeding was observed.
After counting cotton pieces, gauze and instruments, the operation was completed
.
Expand the sponge to fill the bilateral nostrils
.

pathological result

Pathological Diagnosis: Rathke Cyst Discussion

A Rathke cyst is a benign epithelial cyst that originates from the pituitary Rathke's sac
.
Most are pituitary as the center, the larger ones can develop to the suprasellar cistern through the septal septum, and the smaller ones are completely or partially located in the saddle
.

clinical manifestations

Rathke cysts are rare clinically and lack characteristic clinical manifestations
.
The disease is more common in women, most Rathke cysts are small and do not cause symptoms; a few cysts gradually expand, compressing the intrasellar or suprasellar structures, causing clinical symptoms, mainly pituitary dysfunction, visual dysfunction, headache and so on
.

Pituitary dysfunction is mostly manifested as diabetes insipidus, amenorrhea, lactation, acromegaly, hyponatremia, thyroid and adrenal insufficiency
.

CT appearance

Most of the lesions are located in the saddle, some extend upward, and a few are located on the saddle, which are round, oval, or dumbbell-shaped.
Most of the lesions are low-density on plain scan.
The density or slightly high density may be accompanied by the enlargement of the sella, the subsidence of the bottom of the saddle, and the displacement of the pituitary stalk and optic chiasm
.

MRI appearance

Rathke cysts have various signals, and their manifestations are divided into two types:

One is T1 low T2 high signal, the general signal is relatively uniform, the cyst fluid composition is similar to cerebrospinal fluid, and it is characterized by typical eccentric growth;

The other is that T1 high signal and T2 signal are different.
T1 high signal is mainly related to the increase of mucopolysaccharide content
.
A few lesions showed high signal on T1 and low signal on T2, which were mainly related to the coexistence of multiple components such as increased mucopolysaccharide content, chronic bleeding, high cholesterol content, and cell debris in the cyst wall
.

On MRI, the incidence of intracystic nodules in Rathke cyst is 17%-77%, and its signal has certain characteristics, showing short T1 and short T2 signal without enhancement
.

Differential diagnosis

Pituitary adenoma: When the Rathke cyst is small and located in the sellar, those with low signal on T1WI should be differentiated from pituitary microadenoma: the former has a smoother and sharper edge and lower signal; if the small cyst shows high signal on T1WI, it should be differentiated from pituitary adenoma.
Pituitary macroadenoma apoplexy identification: Rathke cyst signal is generally uniform, less expansion of sella, and no change after follow-up, which can be distinguished
.

Craniopharyngioma: Occurs in the suprasellar cistern, the sellar area and the front of the third ventricle.
Most of the tumors are cystic, and a few are solid.
The protein and cholesterol content of the craniopharyngioma affects the CT density and MRI signal, and the enhanced scan is uneven.
strengthen
.
The high incidence of calcification in craniopharyngioma is one of the characteristics of the disease.
CT diagnosis is the most meaningful in the differential diagnosis of Rathke cyst and craniopharyngioma
.

Arachnoid cyst: It contains fluid similar to cerebrospinal fluid, and the signal is a uniform long T1 long T2 signal
.
The signal of the fluid is diverse, even the long T1 signal is generally higher than the signal of the cerebrospinal fluid
.
Therefore, it is generally easier to distinguish
.