orbital dermoid cyst
Introduction
Introduction to orbital dermoid cyst Dermoid cysts and epidermoid cysts (dermoidcystandepidermoidcyst) are congenital cysts. The two cysts are slightly different in pathological structure, but they are basically a disease in clinical, tissue source, clinical manifestations, diagnosis and treatment are basically the same. . It may be that the remains of the surface epithelium during the embryonic period are caught in the suture, and the lesions continue to fall off to form a cyst. basic knowledge The proportion of the disease: the probability of the population is 0.09% Susceptible people: no special people Mode of infection: non-infectious Complications: cellulitis
Cause
Causes of orbital dermoid cyst
(1) Causes of the disease
The dermoid cyst is formed by the implantation of surface ectoderm during the embryonic period.
(two) pathogenesis
During the embryonic period, the epithelium is in contact with the dura mater. As the fetus develops, the skull is formed between the two, separating the epithelium from the meninges. If the two are stuck together, the small epithelium adheres to the dura mater or periosteum during the formation of the skull. Deeply buried in the iliac crest or iliac crest, the ectopic epithelium continues to grow after birth to form a cyst. The cyst inside the sac is adhered to the meninges through the suture or extends into the cranium. The armpit, during the viviparous period, is forced by the pressure of the amniotic membrane. Into the body, is also one of the reasons for the formation of a dermoid cyst, there is no connection between the cyst and the meninges.
Prevention
Orbital dermoid cyst prevention
No need to pay too much attention, timely detection of timely treatment.
Complication
Orbital dermatoid cyst complications Complications cellulitis
Stimulation of infection can lead to sputum cellulitis and intra-abdominal abscesses.
Symptom
Eyelid dermoid cyst symptoms Common symptoms Eyebrow cyst cysts Congestive retinal edema Eyeball protruding optic atrophy
Although the dermoid cyst originated in the embryonic period, except for the cyst located in the gingival margin, the tumor can be found in early childhood. Due to the slow development of the disease and even the quiescent period, the cyst located behind the gingival margin, especially the deep dermatophyte cyst often Symptoms only occur in adolescence, and can also be seen in elderly patients.
The clinical manifestations of this disease depend on the primary location of the tumor. The dermoid cysts located at the temporal margin often occur on the superior side of the temporal margin, followed by the superior and inferior margins of the iliac crest, and sometimes the iliac crest. The upper part of the nest can be found in the early stage of the sputum. The sacral margin is locally raised, the skin color is unchanged, and the semicircular or round mass can be seen. The boundary is clear, slightly elastic, no tenderness, and can be promoted. No adhesion to the skin, no change in eyesight, eyeball position and eye movement. Larger tumors may affect the shape of the upper jaw, or oppression of the eyeball may cause refractive error. It is located outside the temporal margin, mostly at the anterior part of the diaphragmatic muscle. Between the bone wall and the bone wall, the mass is mostly trapped in the bone socket. The content is mostly liquid fat. The local flattening is found in the clinic. The boundary of the peritoneal mass is unclear, and there is a sense of fluctuation. When the tumor is large, the outer wall is pressed. The depression in the sputum, the volume of the sputum becomes smaller, and the eyeball can be prominent, which is generally not obvious.
The person located in the sputum often occurs in the outer upper quadrant of the eyelid, accounting for 69%, followed by the inner upper quadrant, the lower part of the sac, the occasional invasion of the nose and the lacrimal duct. From the depth analysis of the location, it is more common in the front and middle sections. There are fewer cases in the posterior segment of the iliac crest. The interstitial space of the cyst is more common in the subperiosteal space. The cyst compresses the bone wall and forms a depression. The tumor grows between the bone fossa and the periosteum, and can protrude into the cranial cavity or the armpit to form a dumbbell-like cyst. It has also been reported that there are two independent dermoid cysts in the lateral and axillary fossa. The bone wall is intact, the cyst stimulates the periosteum, thickens the margin of the bone, and many bones in the dimple. These changes in the bone form the X-ray. And the basis of CT qualitative and localized diagnosis, the tumor located between the periosteum and the muscle cone is not uncommon. The muscle cone is relatively rare, but it has also been reported in recent years.
The initial clinical manifestation of deep cysts is that the eyeballs are prominent and displaced inward and downward. The lesions progress slowly, even for a long period of time. Therefore, some patients have a late treatment, and the larger ones are often swollen and round. Or ossification, the former is located in the outer space of the muscle cone, the latter in the periosteal space, due to the tumor oppression of the eye, causing refractive error, retinal edema, vision loss, a small number of patients with cystic rupture with inflammatory reaction Eyelid tenderness and eyelid edema, fistula formation or ankle bulging, eye movement disorders and optic atrophy.
Because the tumor mainly occurs in the lacrimal gland area outside the eyelid, symptoms and signs similar to the lacrimal gland tumor appear, such as the eyeball protruding and shifting inward and downward. If the lesion is superficial, the cystic mass can be touched on the outer side of the eyelid, and there is no spontaneous pain. However, patients often complain of headaches. The cyst itself is an inflammatory stimulus. For example, trauma, surgery or spontaneous rupture can cause fistulas. The lesions can be excreted through the fistula. Local skin congestion can sometimes cause sputum cellulitis. symptom.
If there has been a history of surgical resection of eyelid dermoid cysts, recurrence of the lesions should be considered in the years or months after surgery. The cysts are mainly found in the subperiosteum of the orbit, and secondly in the muscle and periosteal space and in the muscle cone. Surgical treatment is more difficult, it can also occur under the skin and does not invade the sputum, a small number of origin in the humerus or under the diaphragm.
Examine
Examination of orbital dermoid cyst
Pathological examination: The general specimens have a round or oval shape, a few dumbbells, and a smooth wall. When the lesion is cut, there is a thin wall around the cyst. It contains oily stench and sebaceous glands and countless Hair, a typical dermoid cyst under a microscope is a circular or elliptical structure, the cyst is lined with a keratinized stratified squamous epithelium, and in some cases, the cyst is lined by a cuboid epithelium (containing a goblet cell). Cysts are thought to be differentiated from the conjunctival epithelium, the two main features of which are skin-like appendages, such as the presence of hair and sebaceous glands in the cystic wall and cystic cavity.
Approximately 38% of orbital dermoid cysts show chronic granulomatous inflammation, often with a foreign body giant cell response around the hair. This inflammation is particularly likely to occur if the cyst has been ruptured due to trauma or has been previously surgically incomplete. .
1. X-ray examination of large orbital dermatoid cysts can be shown in the standard K-point (20° posterior position) and Watt position (45° posterior position), the marginal mass is located on the bone surface, long-term compression of the bone A depression can be formed, a circular low-density area can be seen on the X-ray, and a deep-like dermoid cyst is located outside the periosteum, and the bone wall is pressed to form a bone depression or a hole; on the other hand, the cyst stimulates periosteal hyperplasia, and the X-ray can be displayed in a low-density area. There is a hardened ring around it, mostly located in the upper quadrant of the eyelid. This is a typical X-ray image of a dermoid cyst. This hardening ring is associated with other orbital diseases such as organized hematoma with bone loss, Langerhans histiocytosis and plasma. Cell myeloma is absent, and some chronic mucinous cysts can also show sacral sclerosis, but the degree is lighter than the dermoid cyst, and more obvious is the absence of ethmoid cardboard.
2. Ultrasound examination Because the dermoid cyst contains different sac content, its echo performance is different. A-type ultrasound shows that some cases have an anechoic flat after the high peak of the eye wall, which is the intracapsular fluid, indicating the lesion. There is no echo interface inside, but most cysts have high and low peaks.
Type B ultrasound exploration has the following characteristics:
1 The mass is mostly located outside the iliac crest;
2 is round, semi-circular, or because most of the cyst is located in the bone concave, it is irregular;
3 clear boundaries;
4 The intraepithelial echo may be different due to the composition of the cyst contents. The fluid and keratin mixture in the cyst is characterized by multiple echoes, strong echoes and uneven distribution. This point should be differentiated from cavernous hemangioma; The liquid surrounded by the inner wall of the capsule is characterized by a strong echogenic mass surrounded by a liquid dark area; the liquid in the capsule is a uniform liquid, which is shown as a liquid dark area, and the true epidermoid tumor appears as such an image. ;
5 sound attenuation is not obvious, combined with the cystic effect, the posterior capsule wall echo is stronger, even stronger than the anterior capsule wall;
6 There are obvious compressive deformations. According to the above characteristics, most cases can make accurate histological judgment before surgery.
Color Doppler ultrasonography, the lack of blood vessels in the cyst can not find color blood flow, which is an important marker distinguishing from other solid tumors.
3. CT scan is the most characteristic lesion in the sacral mass due to the complex composition and diverse secondary changes in the dermoid cyst.
(1) Special position: mostly located in the upper quadrant of the ankle, the periosteal space, round or semi-circular.
(2) Diversification of density within the lesion:
1 low density and high density interphase;
2 have high density and low density plane;
3 homogeneous high density;
4 homogeneous transparent area, low density area is intracapsular fat image, CT value is negative, the lowest is -61HU, high density is the detachment of the wall and hair image, CT value up to +77HU.
(3) Intravenous injection of contrast agent such as diatrizoate is ring-enhanced: that is, the wall of the capsule contains blood vessels that can be strengthened, and the lack of blood vessels in the contents is not enhanced.
(4) Injury-like depression or ostium formation of the iliac wall finger: osteophytes can be seen in the ostium, or bone holes can be formed, and the same low-density area exists in the intracranial or axillary region, and other intraorbital malignancy such as lacrimal adenoid cystic carcinoma Tumors sometimes show bone destruction depressions, but lack of bone hyperplasia and low-density areas can be distinguished from dermoid cysts.
(5) Missing part of the wall: the tumor is dumbbell-shaped.
(6) Calcium deposits can be found on the wall of the capsule, which usually occurs in large cysts.
4. MRI examination of lesion morphology with CT, lesion area signal abnormalities, cyst wall mainly composed of fibrous tissue, both T1WI and T2WI showed low signal intensity, which is due to the long T1 of fibrous tissue, short T2, the internal signal of cyst Different signal intensity and different signal intensity, both sweat and sebum, T1WI and T2WI have high signal intensity, such as mixed with more wall leakage and hair, showing high, medium and low signal intensity Or mottled, dumbbell-like dermoid cysts can be seen in the axillary or intracranial abnormal signal area, observed on T2WI more clearly, for bone changes, MRI showed that the lesion is not as good as CT scan.
Diagnosis
Diagnosis and differentiation of orbital dermoid cyst
According to typical clinical manifestations, superficial dermoid cysts of the iliac crest can be diagnosed, and deep cysts can be diagnosed according to typical imaging examinations. The skin or epidermoid cysts mainly occur in young and middle-aged children. It can occur, the clinical manifestation is progressive unilateral ocular protrusion, the lesion is mainly located above or outside the eyelid. CT shows negative areas and bone resorption or destruction in the lesion; however, some cyst contents are homogeneous and high density, no Negative value zone diagnosis is more difficult.
Because the dermoid cyst mainly occurs outside the eyelid, the tumor in the lacrimal gland area should be considered in the differential diagnosis. CT is very important in differential diagnosis, especially in the presence of bone lesions.
