Extrapontine myelinolysis caused by electrolyte imbalance during the management of suprasellar germ cell tumors. Report of two cases

Extrapontine myelinolysis (EPM) is caused by marked fluctuation of the serum electrolyte level. Patients with suprasellar germ cell tumors frequently present with diabetes insipidus, which is often aggravated by administration of steroid hormone. In addition, cisplatin-based chemotherapy is sometimes accompanied by marked serum electrolyte fluctuation because it needs massive hydration to prevent renal damage. Two children with suprasellar germ cell tumors in whom EPM developed secondary to profound hyponatremia and was rapidly corrected are described. The central pons was spared in both cases. Clinically the children showed transient neurological deficits including confusion, pseudobulbar palsy, and deterioration of consciousness. MRI demonstrated bilateral symmetrical, high-signal-intensity (HSI) lesions on T2-weighted images (T2WI) at the basal ganglia and adjacent cerebral cortex. Follow-up T1WI a few months later revealed newly developed HSI lesions in the basal ganglia. The patients gradually improved, but the neurological deficits did not completely disappear. During the perioperative management of suprasellar germ cell tumors, EPM should be considered when a patient has a significant electrolyte imbalance and neurological deficits, especially confusion and pseudobulbar palsy.

Pediatric pineal tumors: need for a direct surgical approach and complications of the occipital transtentorial approach

In an investigation of the benefits and risks of direct surgical approaches to pediatric pineal tumors, the need for such approaches, the feasibility of surgical removal and operative complications were evaluated in 25 histologically proven cases. Five tumors were germinomas (GEs) or GE-predominant mixed germ cell tumors (GCTs), in which stereotactic biopsy can be adequate. Twenty of the 25 pineal tumors (80%) were teratomas (TEs), TE-predominant mixed GCTs or other tumors that need direct surgical approaches. Among the 21 tumors resected by the occipital transtentorial (OTT) approach, 13 were removed radically (>95%) and 6 others, subtotally (>75%). Complications of using the OTT approach included homonymous hemianopsia (7), Parinaud's syndrome (6), other eyeball movement limitation (7), seizure (5), and new hydrocephalus (3). The majority of these were transient, resolving within a few days or months, or easily controlled. The results showed that 80% of pediatric pineal tumors needed direct surgical approaches and that the majority were successfully removed by OTT surgery with an acceptable level of risk.

Intramedullary anaplastic oligodendroglioma in a child

Primary intramedullary anaplastic oligodendroglioma is a rare tumor, only four cases of which have been reported. The authors present the case of a 38-month-old boy with primary intramedullary anaplastic oligodendroglioma. He underwent partial removal of the tumor and spinal radiation therapy. The residual tumor disappeared 12 months after radiation, and 48 months after treatment there was no evidence of recurrence. This case shows that in primary intramedullary anaplastic oligodendroglioma, postoperative radiation therapy confined to the spinal cord can yield an optimal result.

Brain tumor in the first year of life: a single institute study

Brain tumors in infants present special diagnostic and therapeutic challenges. To figure out the clinical features, pathological classification of the tumors and the treatment outcome of infantile brain tumors, 458 children (age<16) with brain tumors were reviewed retrospectively. Among them 21 cases (4.6%) were diagnosed during the first 12 months of life. Two tumors were definitely of congenital origin. The majority of infants with brain tumors presented with increased intracranial pressure. Fourteen tumors were located at the supratentorial area. Sixteen cases had neuroepithelial tumors; astrocytoma (optic pathway), supratentorial primitive neuroectodermal tumor (PNET) and medulloblastoma were found in three cases each. There were two treatment-related mortalities. Compared with the outcomes in older children, the treatment outcome was poorer in medulloblastoma and the optic pathway glioma which showed a higher growth potential. Because of the limited application of postoperative adjuvant therapy, radical surgical removal played a more important role in this age group. The prognosis of patients in whom the tumors could not be totally removed, largely depended on the pathological malignancy of the tumors. Though the treatment outcome was not always dismal, immaturity of the brain, higher growth potential, perioperative risks, limitations in adjuvant therapy, and pessimistic attitude on the part of parents made management more challenging.

Microbial transformation of dihydrosarsasapogenin with Mycobacterium sp

Microbial transformation of sarsasapogenin (1) with Mycobacterium sp. (NRRL B-3805) gave 25(S)-neospirost-4-en-3-one (2) as the sole product in 62% yield. Incubation of dihydrosarsasapogenin (3) led to the isolation of seven products in 0.5 (4), 6.6 (5), 5 (6), 16 (7), 1 (8), 1 (9), and 4.5% (10) yields, respectively, while 15% of 3 was recovered. Among these products, 8 and 9 were C22 steroids, and 10 was a C19 steroid. Isolation of these C19 and C22 steroids indicated that this microorganism is capable of cleaving the ether linkage between C-16 and C-22 in 3. In addition, 12 alpha-hydroxylation was also observed in all these three metabolites.

Pineal tumors: experience with 48 cases over 10 years

The authors retrospectively reviewed 48 patients treated at Seoul National University Hospital (SNUH) between 1986 and 1995. There were 35 children and 13 adults, accounting for 10.1% of 345 pediatric and 0.68% of 1914 adult brain tumors in SNUH during the same period. The 48 cases consisted of 33 cases of germ cell tumor (69%, GCT); 6 of pineoblastoma (PB, 12.5%); 3 of pineocytoma (PC, 6.3%); 3 of anaplastic astrocytoma (6.3%); 1 of astrocytoma; 1 of glioblastoma; and 1 of ependymoma. The median age was 13 years (range 1-59) and the male-to-female ratio was 3.36:1. The most frequent presenting symptom was due to increased intracranial pressure (90%), followed by Parinaud syndrome or diplopia (50%). Patients with a benign tumor, such as teratoma (TE), astrocytoma, or ependymoma, underwent surgery by the occipital transtentorial approach (OTT) for attempted radical resection without adjuvant therapy, while patients with immature teratoma (imTE), PC, and anaplastic astrocytoma underwent regional radiotherapy (RT) after debulking via OTT. Seven patients with nongerminomatous malignant GCT (NG-MGCT) and 3 with germinoma (GE) underwent craniospinal radiation only, 6 with GE, a NG-MGCT, and 2 with GE+TE received craniospinal radiotherapy (CSRT) after debulking via OTT. Three patients with GE, 4 with NG-MGCT, and 3 with PB underwent radiochemotherapy after debulking via OTT. Forty-four patients were followed up after treatment. The median follow-up period was 36 months. All patients with GE were alive after RT at 36 months (median) of follow-up (range 7-70 months). All with GE+TE and TE were alive. Three patients with PC or astrocytoma were also alive with stable or no evidence of disease. In 1 of the 3 cases of imTE there was a recurrence. However, 4 patients with NG-MGCT died, all of whom had undergone CSRT only; 2 PB patients were alive (12, 19 months), 1 in a moribund status (36 months), and 2 were dead (6, 60 months). The overall mean survival time with pineal tumors was 66 months and the 3-year survival rate was 84% with minimal posttreatment complications. It is concluded that pineal region tumors have male and childhood predominances, and the most common tumor is GCT. The majority of pineal region tumors are malignant. Pineal region tumors can be approached safely and effectively and the surgical complications are mostly transient. Their prognosis is dependent on the pathologies and treatment modalities.

Functional significance of the TATA element major groove in transcription initiation by RNA polymerase II

The binding of TFIID to the TATA element initiates assembly of a preinitiation complex and thus represents one of the most important steps for transcriptional regulation. The fact that the TATA binding protein (TBP), a subunit of TFIID, exclusively contacts the minor groove of the TATA element led us to ask whether the major groove of the TATA element plays any role in transcription initiation or its regulation. Our results show that modifications of the major groove of the TATA element in the adenovirus major late promoter have no effect on TFIID binding affinity or on transcription in a cell-free system reconstituted with purified factors. However, major groove modifications do decrease the levels of both basal and activator-mediated transcription in unfractionated nuclear extracts, indicating that the intact structure of the major groove of the TATA element is functionally important for transcription initiation in a more physiological context.

Functional opening of the fourth ventricular outlet in C57BL/6J and delayed splotch mouse embryos

To compare the functional development of the fourth ventricular outlet in the myeloschisis-Chiari malformation complex with that of a normal brain, the chronological development of the outlet in C57BL/6J non-neural-tube defect mouse embryos was examined as the first step. Then we compared the results with those of homozygotic delayed splotch (Spd) mouse embryos which had neural-tube defects (NTDs). Ferrous chloride (Prussian blue) solution was injected into the lateral or mesencephalic ventricle on gestation days 13-16 in the case of control C57BL/6J mouse embryos and on gestation days 14-16 in the case of homozygotic Spd mouse embryos which had open spinal NTDs and hindbrain anomalies comparable to human Chiari malformation. At 30 min after the injection, acid fixative was infused through the heart to set off the Prussian blue reaction, which makes the dye visible by the precipitation of ferric chloride. According to the present method, more than 75% of C57BL/6J mouse (non-NTD control) embryos showed the evidence of function of the fourth ventricular (4V) outlet from gestation day 15. It was difficult to apply the same method to Spd mouse embryos with NTDs due to the small size of ventricles. Only 4 injections were successful, of which 3 showed the functioning evidence of the 4V outlet. Though the number of mouse embryos with NTDs studied was small, the results suggest that the chronological progress of functional opening of the fourth ventricle in mouse embryos with NTDs is similar to that of control non-NTD embryos.

Complications of pediatric craniofacial surgery in the Orient: analysis of a 10-year experience

Numerous reports on the complications of craniofacial surgery have been published in the western world. However, relatively little such information concerning Oriental populations has been documented. We therefore set out to provide a retrospective analysis of all the complications of craniofacial surgery encountered during the 10-year period of 1986 to 1995 at Seoul National University Children's Hospital, the only children's hospital in Korea. Forty-nine children underwent 57 consecutive craniofacial procedures at our institution during 1986 to 1995. A retrospective chart analysis of the frequency and types of complications was performed. Mantel-Haenszel chi-square tests were then calculated for several factors, including age at surgery, duration of surgery, intraoperative losses of hemoglobin and hematocrit, total amount of blood transfusion, and the number of complications according to year, diagnosis, and operative procedure to find any significant correlation with the incidence of complications. Mortality was 1.8%. The major complication rate was 7.0% and included cases of visual loss and persistent cerebrospinal fluid leak. Analysis revealed the presence of several trends, including an increased incidence of complications with increased patient age at surgery, duration of surgery, and intraoperative loss of hematocrit. The number of complications was also noted to increase in cases with complex craniofacial synostosis syndromes (Crouzon's, Apert's Antley-Bixler, etc.) and tumors of the orbit and cranium. Finally, complications were noted to decrease in recent years, most likely due to the increased experience of our craniofacial team. Nevertheless, statistical analysis revealed that the incidence of complications correlated significantly only with increased duration of surgery (p < 0.05). The results of our study indicate that although craniofacial surgery in the Orient carries an inherent risk for significant complications, the risk can be minimized and the rate of mortality and major complications kept to an acceptable level by a careful and experienced craniofacial team. Groups at most risk for complications are those with a long duration of surgery.

Cerebral leiomyoma in a child

A case of primary cerebral leiomyoma in a 12 year-old boy with unique clinical features is described. He presented with fever, and the magnetic resonance imaging demonstrated a well demarcated mass in the subcortical white matter of the right temporal lobe. The mass showed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images with a strong homogeneous gadolinium-DTPA enhancement. The mass was removed in toto and was composed of fasciculating, monotonous oval to spindle cells which had both immunohistochemical and ultrastructural features of primitive smooth muscle differentiation. The patient is free of recurrence during the follow-up period of 56 months. Detailed clinicopathologic findings are discussed.

Renovascular hypertension in children with moyamoya disease

OBJECTIVES

To examine the incidence, clinical and radiologic findings, and response to treatment of renovascular hypertension (RVHT) in moyamoya disease (MMD).

METHODS

A retrospective analysis of medical records in six RVHT cases (8.3%) among 72 MMD patients observed from November 1987 to December 1995.

RESULTS

The age at onset of MMD ranged from 9 months to 7 years 1 month (mean, 3.3 years). The most common initial manifestation of MMD was transient ischemic attack. Hypertension was detected between 4 years 4 months and 12 years 3 months (mean, 7.87 years). Unstimulated plasma renin activity was elevated in all six cases. Renal ultrasonography and captopril technetium 99m-labeled dimercaptosuccinic acid scan showed abnormal findings in four of five and in three of four available studies, respectively. However, both imaging studies showed abnormal findings only in the most severely affected kidneys even with bilateral renal artery stenosis. Renal arteriography revealed bilateral lesions in three of the patients and unilateral lesions in the others. Renal angioplasty was performed in four cases but was successful in only one and partially successful in another. A renal artery specimen obtained during renal autotransplantation showed intimal fibroplasia. At the last follow-up, one patient had normal blood pressure without the use of antihypertensive agents, but the other five patients needed this medication to control blood pressure.

CONCLUSION

Because RVHT may be more commonly associated with MMD than has hitherto been appreciated, it is recommended that blood pressure be carefully followed and that diagnostic procedures for RVHT be carried out in hypertensive patients with MMD.

Slipped capital femoral epiphyses in a patient with primary hyperparathyroidism

Slipped capital femoral epiphyses are rarely associated with primary hyperparathyroidism, and only four cases have been documented in the English literature. We report such a case. A 13-year-old boy presented with bilateral slipped capital femoral epiphyses. Investigation showed that he had primary hyperparathyroidism due to a parathyroid adenoma. The adenoma was removed, and then the epiphyses were pinned in situ 3 weeks later. The pins were removed 3 months postoperatively when the physes had closed. The patient had a painless hip 1 year later at follow-up. We concluded that identification and excision of the hyperparathyroid adenoma and in situ pinning of the slipped epiphyses results in satisfactory treatment of the condition.

Reverse pedicled lateral arm flap for reconstruction of posterior soft-tissue defects of the elbow

Posterior soft-tissue defects of the elbow are difficult to reconstruct by conventional techniques such as closure by approximation or skin graft. An ideal technique should be an easy and reliable one-stage procedure that provides predictable surgical results with regard to elbow function and cosmesis. This report details our experience in 7 patients who underwent a one-stage procedure for coverage of the posterior elbow employing the reverse pedicled lateral arm flap. All flaps survived and all patients were able to resume full range of motion of the elbow joint at the 6-month follow-up. Complications included forearm paraesthesia in 3 patients and conspicuous scarring in a young female patient. We emphasize two valuable refinements in surgical technique including measuring posterior elbow defect in full flexion and postoperative elbow extension splinting. In trauma-related defects of the posterior elbow, a preoperative angiogram is important before raising this flap.

Pyomyositis of the calf muscles mimicking distal deep venous thrombosis: a case report

Pyomyositis is a pyogenic infection of skeletal muscle. It is relatively rare in temperate climates. Unfamiliarity with the lesion may lead to a delay in diagnosis. This report describes pyomyositis of the calf muscles in a patient with chronic hepatitis whose clinical symptoms simulated those of distal deep venous thrombosis. The correct diagnosis was not made until computed tomography revealed a local abscess in the calf muscles.

Bobble-head doll syndrome associated with subduroperitoneal shunt malfunction

Bobble-head doll syndrome is known to be associated with aqueductal stenosis or cystic lesions of the III ventricle. The direction of movement is usually vertical. In the literature, only five cases of purely horizontal movement have been reported. Bobble-head doll syndrome manifested as a sign of shunt malfunction has been described in one case with a ventriculoperitoneal shunt. The authors report on a 10-year-old boy who showed subduroperitoneal shunt malfunction associated with horizontal bobble-head doll syndrome. The head bobbing disappeared immediately after shunt revision. Unlike the previously reported cases, in the present case the lesion was asymmetric, though the significance of this for the lateral movement is not clear. This case also showed more marked ventricular dilatation on subduroperitoneal shunt malfunction than in the pre-shunt state. The underlying mechanism of the ventricular dilatation is unknown.

Choroid plexus carcinoma in an infant

Choroid plexus carcinoma is a rare tumor and has a strong tendency to spread along the cerebrospinal fluid pathway. The tumor frequently occurs in infants. Radiation therapy is not indicated in infants and the response of this tumor to chemotherapy is variable. Therefore, surgical removal plays a major role in the management of this tumor, especially in infants. A 2-month-old girl with an acute communicating hydrocephalus was presented. Through the left posterior parietal transcortical approach, a choroid plexus carcinoma which had poor demarcation from the posterior thalamus and the medial wall of the lateral ventricle was subtotally (> 95%) removed. Postoperatively a ventriculoperitoneal shunt was inserted. Chemotherapy was refused. Magnetic resonance imaging taken at 11 months after surgery showed multiple intracranial seeding of the tumor. She was in a bed-ridden state. This case revealed the aggressive behaviour of choroid plexus carcinoma in an infant and the dismal result of subtotal removal alone, though it is rather radical.

Metabolic characteristics and enflurane defluorination of cytochrome P450-dependent monooxygenases in human hepatocellular carcinoma

BACKGROUND

Xenobiotic metabolism and defluorination capacity of microsomal monooxygenases were investigated in vitro through the surgical specimens of liver resected from patients with hepatocellular carcinoma and patients of extrahepatic pathology as control.

METHODS

In microsomes of hepatocellular carcinoma tissues, the activities of cytochrome P450-dependent monooxygenase isoenzymes 1A1, 2B1, and 2E1 were evaluated in vitro by reacting with the specific marker substrates benzo(a)pyrene, benzphetamine and aniline, respectively, in the generating incubation system. The distant normal liver tissues and tissues from control patients with extrahepatic lesion were also investigated for comparison. The ability of enflurane defluorination was assessed by Orion combined for detection of free fluoride ion production.

RESULTS

Concentrations of P450 total content, cytochrome b5, and NADPH-cytochrome c reductase showed parallel and marked reduction in tumor tissues when compared with its distant normal regions or normal livers. The monooxygenase functions displayed significant decreases within the tumor tissues as benzo(a)pyrene hydroxylation > or = benzphetamine demethylation > aniline hydroxylation in magnitude. Defluorination of enflurane also markedly decreased in tumor tissues comparing with normal livers.

CONCLUSIONS

These marked reductions in the compositions and in vitro metabolic activities, including defluorination of anesthetics, in the cytochrome P450-dependent monooxygenases within the tumor tissues characterize the unique pattern of xenobiotic metabolism in patients with hepatocellular carcinoma.

Cerebral sparganosis in a child

Cerebral sparganosis in childhood is very rare. Until 1996, 2 cases in children up to 15 years of age had been described. We report a case of cerebral sparganosis in a 6-year-old girl who presented with seizures. Sequential brain magnetic resonance imaging scans spaced over 4 months showed a lesion which migrated from the right parieto-occipital region to the right occipital region. The enzyme-linked immunosorbent assay for antisparganum antibody was positive. She most likely contracted sparganosis from worm-infested spring-water. A live worm with surrounding granulomatous tissue was removed, and the enzyme-linked immunosorbent assay for antisparganum antibody converted to negative 12 months following surgery. In areas of endemic sparganosis, the possibility of cerebral sparganosis should be considered, even in a child, if the patient shows a migrating granulomatous lesion.

Cerebral sparganosis: clinical manifestations, treatment, and outcome

Cerebral sparganosis is a rare parasitic disease caused by infestation by the plerocercoid larva of Spirometra mansoni. The authors retrospectively analyzed 17 cases of cerebral sparganosis treated at Seoul National University Hospital between 1986 and 1994. The patients' ages at diagnosis ranged from 6 to 57 years (median 32 years) and the male/female ratio was 13:4. Diagnosis was based on radiological findings, serological test results, operative findings, and histopathological examinations. Characteristic magnetic resonance (MR) findings consisted of widespread white matter degeneration and cortical atrophy, mixed-signal lesion (low in the central and high in the peripheral regions on T2-weighted images) with irregular dense enhancement of central foci and changes in the location and shape of the enhancing lesion in follow-up studies. Ten patients underwent surgical removal of the parasitic lesion, six received medical treatment alone (five with praziquantel and one with antiepileptic drugs), and one underwent insertion of a ventriculoperitoneal shunt and a course of praziquantel. Follow-up periods ranged from 13 to 111 months (mean 49 months). Seven patients who underwent complete removal of the lesion, live worm, or degenerative worm with surrounding granuloma showed a favorable course. Patients who received medical treatment alone or incomplete removal exhibited progression in their neurological deficits and their seizures could not be controlled. Medication with praziquantel seemed to have no killing effect on live worms. The authors conclude that MR imaging is the most valuable modality for the early detection of cerebral sparganosis and that complete surgical removal of granuloma together with worms, whether they are alive or degenerative, is the treatment of choice.

Experimentally induced Chiari-like malformation with myeloschisis in chick embryos

Though several pathogenetic theories concerning the frequent association of Chiari malformation and hydrocephalus with myeloschisis have been suggested, none of them explains all the aspects of the disorder. To investigate whether myeloschisis is the direct cause of Chiari malformation and hydrocephalus or these conditions are the results of another basic event, we observed the morphological changes of the posterior cranial fossa and its components in the chick embryos with surgically induced myeloschisis. To make myeloschistic lesions, we opened the neural tube for a length of 9-11 somites in Hamburger and Hamilton stage 16-19 chick embryos. They were divided into cervicothoracic (C-T) and lumbosacral(L-S) groups according to the area of incision. The embryos were re-incubated until postoperative day 11. In the control group, embryos were incubated with the eggshell window open as their experimental counterparts. The survival rates of each group were as follows; 11% (9 survivors/85 operated embryos), 8% (7/83), and 17% (10/60) in the C-T, L-S and control groups, respectively. Myeloschisis positive rates were 100% in the operated groups and 0% in the control group. The heads of embryos were sectioned along the sagittal plane to observe the morphological changes in the posterior cranial fossa and its components. Of the survivors, five in the C-T group, two in the L-S group and six in the control group were available for light microscopic inspection. In the majority of embryos with myeloschisis, without difference between the C-T and L-S groups, the fourth ventricles were smaller than those of the control group and the subarachnoid spaces in the posterior cranial fossa were also narrower. In embryos with severe changes, the cerebellum displaced downward comparing with that of the control embryos. No evidence of hydrocephalus was present Though not always typical, morphological changes similar to Chiari malformation were observed in chick embryos with surgically induced myeloschisis. It suggests a strong direct causal relationship between the two conditions and supports the theories of derangements in cerebrospinal fluid dynamics rather than those of primary mesenchymal or neural origin as a pathogenetic mechanism of Chiari malformation.

Concanavalin-A-induced open neural tube defects in chick embryos

Open neural tube defects developed in 12 of 122 alive chick embryos treated with exogenous lectin (concanavalin-A) at stages between 10 or 14 as defined by Hamburger and Hamilton. Embryos treated at stage 10, the time of anterior neuropore closure, developed exencephaly or extensive neural openings from the level of rhombencephalon to the thoracic spinal cord, while embryos treated at stages between 11 and 14, at posterior neuropore closure, developed only small myeloschisis in the thoracolumbar region. The failure of neural tube closure at a critical time is a major cause of neural tube defects.

Primary intramedullary spinal cord primitive neuroectodermal tumor with intracranial seeding in an infant

Primary spinal cord primitive neuroectodermal tumor (PNET) is a rare entity. In all 13 cases have been reported in the literature, including 3 with intracranial seeding. A 3-month-old girl with involvement of the spinal cord below the mid-thoracic level is described. The brain MRI revealed findings indicative of seeding along the intracranial subarachnoid space. Biopsy, duraplasty and removal of laminotomy flap were done. In spite of a good response to the first cycle of postoperative "8-drugs-in-a-day' chemotherapy, further treatment was refused. She died 21 days after the onset of leg weakness, which reveals the rapid progression of untreated cases. To our knowledge, this is the first case of spinal cord PNET with parenchymal involvement that has been described in an infant.

Promotion of synthetic amyloid beta-peptide fibrillization by cell culture media and cessation of fibrillization by serum

Dulbecco's modified Eagle's medium promotes aggregation and fibrillization of the synthetic amyloid beta 1-40 and beta 1-42 peptides more than RPMI and OPTI media. Fibrillization in all of these media is faster than in phosphate-buffered saline and Tris buffer. Normal and heat-inactivated fetal bovine and human serum abolish amyloid fibril formation in buffers and cell culture media. Fibrillar amyloid formed during 2-day-long incubation in cell culture media and buffers is defibrillized by 1-day-long treatment with human and bovine serum. This study indicates that amyloid beta fibrillogenesis in cell culture should be studied in serum-free media or in media with a low concentration of serum.

Terminal myelocystocele--a case report

Terminal myelocystocele is a rare form of occult spinal dysraphism in which the hydromyelic caudal spinal cord and the subarachnoid space are hemiated through a posterior spina bifida. A 1.5 month old boy presented with a large lumbosacral mass and urinary incontinence. The magnetic resonance imaging, operative findings and pathological findings revealed a low lying conus with a dilated central canal dorsally attached to the subcutaneous tissue. Ventral subarachnoid space was enlarged and herniated through the laminar defect of the sacrum. The lesion was typical of a terminal myelocystocele. The clinical features are different from those of myelomeningocele in many aspects. Though the incidence is low, terminal myelocystocele should be included in the differential diagnosis of congenital lesions presenting as a lumbosacral mass.