The Congenital Tumors In Vertebral Canal

The congenital tumors in vertebral canal develop from the remnant blastoderm cells in embryonic development period, and can be classified imto epidermoid cyst dermoid cyst teratoma-. Enterogenous cyst lipoma and chordoma according to the difference of their tissue: structure. They can be made up of one blastodermic layer and two or even more blastodermic layer as well. Epidermoid cyst only composes of epiderm and desquamation, whereas dermoid cyst not only epiderm and desquamation but also derma and appendages of the skin such as coil gland sebiferous gland hair follicle and etc. Teratoma includes more than 3 blastodermic layers. Enterogenous cyst can be generally regarded as teratic cyst or teratoma because it is mainly made up of endoblast tissue on histology and comes from the aberrance of coelenteron in vertebral canal.It is still unclear about the pathogenesis of the congenital tumors in vertebral canal.However, many scholars in recent years presume that they stem from the underdevelopment of primitive neurenteric canal dorsal chord and neural tube or the derangement caused by the interaction among of such structures mentioned above endoderm mesoderm and ectoderm. Enterogenous cyst: typical cyst is transparentcyst within colorless mucus and thin wall which is made up of one layer or pseudo-stratified cuboidal epithelium or columnoepithelialic cell is nourished by angio-connective tissue. Epidermoid cyst and dermoid cyst have their own characteristics on histology because of the difference of the detained cell component although they all originate from the ectoderm. Epidermoid cyst only contains epidermal tissue while besides epidermal tissue dermoid cyst also contains derma and appendages of the skin such as coil gland, sebiferous gland, hair follicle. Teratoma involves three blastoderm tissue, and liparomphalus mainly mesoderm tissue. Developed from ectopic or residual embryo- notochord, chorcoma is defined as the category of malignant tumors because its bionomics of invasive growth is similar to malignant tumor's although its morphology shows innocence.Diseased region: epidermoid cyst and dermoid cyst can be found in any position in vertebral canal, but often near spinal cord of cervico-thoracic segments conus cauda and eguina. Enterogenous cyst is often located ventri-side of spinal cord in cervico- thoracic segments, but sometimes intraspinal cord or dorso-part of spinal cord, while lipoma often cervical segments or thoracic segments in vertebral canal. Chordoma tends to appear in sphenoid- occiput part and sacro-caud segment because incompletely degenerated notochord often occur at ths extreme of the spine.Because the course of disease is very long, the most congenital tumors in vertebral canal make an compressive lesion on vertebra and widen the corresponding vertebral canal except chordoma which causes the irregular and dilatancy destruction of vertebra accompanying with the mass shadow of soft tissue and spot-lamellar calcification. The specificity on X-ray and CT is not so good. MRI can clearly tell the difference of every kinds of tissue in vertebral canal because of its high density resolution, so it has obvious superiority in discernment of the congenital tumors in vertebral canal. Enterogenous cyst is difficult to tell from arachnoid cyst and dermoid cyst on MRI because there is no special feature, while the characteristics that Enterogenous cyst often grows up from the ventri-side of the spine cord or inserts into the spine cord or combines with other defoimations can help to basically define thenature -. location and range. Epidermoid cyst> dermoid cyst and teratoma tend to grow up near the migration of thoracic-waist segments n conus cauda and eguina.-Sometimes the appearance of Epidermoid cyst and dermoid cyst on MRI is similar so it is difficult to discriminate. To diagnose dermoid cyst it is the mainstay that there is high signal on external and low signal on internal on T1W I while high signal on T2 W I or confounding signal on T1W I and T2 W I. Dermoid cyst and teratoma mainly show a little high signal on T1W I and accompany with patching high and equal signal while teratoma can show very low signal. The teratoma is easy to tell from dermoid cyst if there is bone component in it. Lipoma on SE scanning of MRI shows high signal on both T1W I and T2 W I but show low signal after fat-suppression. Chordoma shows low and equal signal on Tl W I and high signal on T2 W I and accompanied with obvious destruction of bone. Chordoma and capsule wall of the epidermoid cyst and epidermoid cyst can be strengthened lightly and the others of the congenital tumors in vertebral canal have no intensification on MRI contrasted by Gd-DTPA, which is the common characteristics.Clinical manifestation: the morbility of the congenital tumors in vertebral canal in male is superior to that in female, and the age of onset is usually little young, case history is always a little long because the tumor is mainly benign. The mainly clinic manifestation is relative to the location of the tumor such as nerve root irritation and spinal compression while each tumor has its own feature. Enterogenous cyst has a little long case history and intermittent onset, and has earlier and heavier dyskinesia because it is often located at ventri-spinal cord, and sometimes intermittent fever or increased symptom after trauma that may be caused by rupture of the cyst and high protein liquid of cyst entering into the subarachnoid space or central canal, as well as even hydrocephalus if there is adherence in subarachnoid space. Epidermoid cysU dermoid cyst and teratoma: because they are mainly located at inferior extremity of spinal cord> conus cauda and eguina, such tumors mostly cause waist and leg pain and dysfunction of rectum and bladder, so approximately 80% patients has dysfunction of urinate and defecation that sometimes is the first symptom. Inferior extremity of spinal cord can be adhered and fixed to the lower position in vertebralcanal when the cyst is combined by bifida of lumbosacral area, and the cyst can cause palsy of upper motor neuron in both lower extremities but usually atypical although it has the lower position. Some patients have the history of recurrent attacks of meningitis. Symptoms and signs of chordoma are decided by the location of the tumor and the compressed degree of the surrounding structure. The symptoms of chordoma in sacroiliac is light and lack of characteristic, usually only show the pain on inferior lumbar or sacroiliac, then the pain of lumbar and leg and numbness of inferior extremity. The inflated lump can be touched on pars sacralis when the tumor grow toward back. When the tumor grow into the pelvis, it can press the rectum and cause constipation, and the lump can be touched in front of pars sacralis and can not be moved by anus finger-check. Sphincter dysfunction may appear as well when cauda equina nerve is involved in. Urinary and fecal incontinence can be caused by tumor when it impacts the II -—IV nerve sacralison both sides. When the tumor is located in other position, there will be pain in earlier period because the nerve root was involved and then the symptoms of the compressed spinal cord such as the weak of limbs in later period because vertebral body is destroyed and sink. Liparomphalus: it develops slowly, the manifestation is often numbness of the limbs and disturbance of coordination because the tumor is soft and usually located at the back of the spinal cord so that it press the nerve root lightly, and the pain of the nerve root seldom appears, but the symptoms of transverse lesion in spinal cord can be shown when the tumor is large and press the spinal cord heavily.Management: the only efficient method to treat the congenital tumor in vertebral canal is exairesis at present, the degree of excision depends on the size> location and adhesive with the spinal cord and nerve tissue, it also affects the prognosis obviously. It grows slowly and has a long history because it is benign, often large at final diagnosis. The extramedullary tumors can usually be excised completely and have a good prognosis if they are located in cervico-thoracic segments. The total removal is difficult because the wall of the tumor adhere with terminal cone of spinal cord and cauda equina if the tumors are located in thoracic waist segments and lumbar segments. The appliance of micro-operative technique can improve the rate of thetotal removal. The normal blood vessel must be protected well. Generally, the extramedullary and epidural tumor should be completely excised as you can, but the intramedullary tumors or the tumors involved spinal cord should not be requested the total removal excessively. The manipulate must be delicate because the compensation is close to exhaustion for long period pressure and destruction, and light injury may cause severe functional impairment. Such intramedullary tumors as lipoma> teratoma and part of cystic tumors often adhere with normal spinal cord and nerve tissue closely and without obviously interface. During operation the internal part of tumor should be excise firstly, then the wall in piecemeal under microscope, and the reservation of function is superior to the complete excision, and the patients with part excision may have good prognosis because such tumors are benign and develop slowly. The surrounding structure and subarachnoid space should be protected well during the removal of the dermoid cyst and epidermoid cyst in order to avoid the content entering into subarachnoid space and causing aseprtic inflammation so the plenty of normal saline should be used repeatedly to wash the cavity of tumor The capsule wall should be removal as much as possible on the premise not doing harm to the spinal cord and nerve tissue. The symptom is estimated aggravated after excision if the capsule wall adhere with surrounding structure tightly, so it can be preserved. Firstly iodine tincture is applied on the capsule wall and then alcohol for deiodination, and make the capsule wall outpocketing with the incised dural, and let secretion of capsule wall grow toward the outside of the vertebral canal and absorded partly by the muscle to prolong the time of symptom appearing even it recurs again. In addition, the hide sinus incorporated with tumor should be removed at the same time. If the tumor recur and make symptom worse, the second operation is the only treatment.