INTRAVENTRICULAR TERATOMA ABSTRACT ID : IRIA - 1157

INTRODUCTION Congenital intracranial tumors are rare and accounts for 0.5 to 1.5% of all childhood tumors. Teratoma belongs to the group of germ cell tumors. Classified as Mature or immature teratoma. MATURE TERATOMA originates from three, fully differentiated germinal layers (ectoderm, mesoderm, endoderm). IMMATURE TERATOMA originates from more primitive elements of all or any of the three germinal layers. The pure intraventricular location of teratomas is a quite rare entity with few cases reported in adults and pediatric case reports. Imaging plays an important role in the diagnosis of this condition by characterizing the nature of the lesion.

CASE REPORT A 26 year old woman came with H/0 – Focal seizures about 1-2 episodes daily since birth, lasting for 5 mins. Right forearm and hand weakness- past 11 years, progressive in nature. Delayed developmental milestones, Obstetric history: Normal vaginal delivery, no antenatal scans done. No previous imaging was done. Not a known case of Diabetes Mellitus/Hypertension/Tuberculosis. Family history- Nil.

CLINICAL EXAMINATION: Afebrile, vital stable. No pallor/icterus/cyanosis/clubbing/pedal edema/lymphadenopathy SYSTEMIC EXAMINATION: Other systems – normal. CNS- Motor examination- 2/5 in right hand and forearm. Sensory examination- within normal limits. Cranial Nerve examination- within normal limits. PROVISIONAL DIAGNOSIS: Seizure for evaluation.

BACKGROUND Teratoma are tridemic masses that originate from displaced embryonic stem cells. Account for 2-4% of primary brain tumors in children Commonest location in body - sacrococcygeal/gonadal/ mediastinal/ retroperitoneal and intracranial locations. Common locations in brain - midline in the pineal and suprasellar regions/ quadrigeminal plate/ walls of 3rd ventricle and vermis. Less common- basal ganglia and cavernous sinus. Very rare- lateral ventricle. Peri and antenatal presentation- higher risk of adverse outcome.

Three types : Mature teratoma - well demarcated, lobulated tumors that contain all three germ layers. 1) Ectoderm: skin, hair and dermal appendages(eg: sebaceous glands) 2) Mesoderm: cartilage, bone, fat and muscle. 3) Endoderm: respiratory or enteric epithelium lining intratumoral cysts. Immature teratoma - complex admixture of at least some fetal-type tissues from all three germ cell layers in combination with more mature elements. - Cartilage, bone, intestinal mucous and smooth muscle intermixed with primitive neural ectodermal tissue. - Hemorrhage and necrosis are common.

Malignant transformation variant arise from immature teratomas and contain cancers like Rhabdomyosarcoma or undifferentiated sarcoma. The intracranial teratomas can be classified into three types based on distribution: 1)Diffuse form with associated extensive destruction and replacement of brain tissue. 2)Localized form and less extensive form. 3)Massive variant with extension through the skull base into the face and neck region.

CLINICAL FEATURES: TUMOR MARKERS: 90% of teratomas are found below 20 years of age (most: 10-12 years) Male-to-female ratio: 2.5:1 symptoms are due to hydrocephalus and increased intracranial pressure TUMOR MARKERS: Malignant yolk sac endoderm with aggressive component show elevated levels of AFP or beta-HCG in serum and/or CSF. Transcription factors GATA-4 and GATA-6 may also be elevated in mature and immature teratomas

IMAGING FEATURES CT: show presence of fat and calcification. Usually have cystic and solid components. Post contrast shows variable enhancement  of the solid components.

MRI : Complex- appearing multiloculated lesion with heterogenous intensity in T1 and T2- weighted images. Presence of calcifications, fat, calcification, numerous cysts and solid components. Fat and proteinaceous/lipid—Hyperintense in T1 and T2 sequences. Soft tissues-- isointensity in both T1 and T2 sequences. Calcification and blood products—Blooming in Gradient sequence. Post contrast shows soft tissue and capsule enhancement.

IMAGING FINDINGS CT SCANOGRAM Shows multiple ill-defined calcific foci.

CT Heterogenous density lesion with cystic (yellow arrow), fat (blue arrow) and calcific (red arrow) components is seen predominantly in the left lateral ventricle involving foramen of monro associated with marked hydrocephalus and parenchymal wall loss.

MRI Heterogenous signal intensity mass lesion showing solid and cystic components. Few foci of fat (yellow arrow) in T1W and T2W sequences appearing hyperintense which is suppressed on T1 FAT-SAT sequence.

T2 FFE axial sequence shows patchy areas of intra-lesional blooming artefacts, suggesting calcifications(red arrow). T1W sagittal sequence shows a cystic component(yellow arrow) of the mass lesion compressing the aqueduct of Sylvius causing dilatation of the third ventricle(blue arrow).

T1 Post contrast axial and sagittal sequences showing moderate heterogeneous enhancement (red arrows) of the solid components and peripheral wall enhancement of the cystic components (yellow arrows).

DIAGNOSIS Imaging features showing presence of intraventricular heterogeneous irregular lobulated mass with regions of low and high attenuation representing fat and calcification respectively, are more in favour of Matured Teratoma. Differential diagnosis: PNET- only cystic and calcific components, no fat is seen. Ependymoma- necrosis, coarse calcification and hemorrhage frequently seen with no fat Choroid plexus carcinoma- arise in choroid plexus, necrosis is present with no fat Intraventricular meningioma- well defined round tumour with homogenous enhancement, occasionally calcification, no fat.

CONCLUSION The evaluation of the intraventricular mass provides a significant clinical challenge to radiologists. This entity is infrequently encountered in adults. Our case illustrates classical imaging features of an intraventricular teratoma, one of the rare location for this tumour to be present. Even though Histopathological correlation being the confirmatory finding for final diagnosis of teratoma, in our case imaging findings were very much conclusive of teratoma.

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