IMAGING FEATURES OF TUMOR EXOPHTALMOS IN CHILDREN M. LIMEME, H. ZAGHOUANI BEN ALAYA, S. KRIAA, H. AMARA, D. BEKIR, CH. KRAIEM Imaging department, Farhat Hached Hospital, Sousse, Tunisia PED16

Introduction  Clinical signs are frequent in children exophtalmos.  Etiology: predominant tumor.  Imaging: diagnostic & etiology.

Introduction  The malignancy is rare (20%) and includes primitives tumors (retinoblastoma, rhabdomyosarcoma) and metastasis.  The benign pathology, the most frequent (80%), is varied. The dermoid cyst represents almost half of the orbital masses.

Objectives Show the interest of the imaging methods, particularly computed tomography (CT) and magnetic resonance imaging (MRI), in the exploration of the tumor exophthalmos in children.

Materials and Methods  14 cases of tumor exophthalmos in children were retrospectively reviewed.  They were collected in our department over a period of two years ( ).  12 were explored by a cranio-orbital CT  MRI was performed in 12 patients.

Results  The average age of patients was 6 years.  An unilateral involvement was noted in 93% of cases.  89% of cases of tumor exophthalmos due to malignant tumors. The most common pathologic type is the retinoblastoma (5 cases) followed by the rhabdomyosarcoma (3 cases).  Others are less common pathological types: capillary hemangioma (1 cases), optic nerve glioma (1 cases), lymphoma (1 cases), orbital metastasis of a neuroblastoma (1 cases), leukemia (1 case), histiocytosis X (1 case).  Radiological features were various, depending on the etiology.

Discussion

Retinoblastoma Malignant eye tumor of children Average age between 1 and 2 years. Clinical signs: - Leukocoria Strabismus - Ocular inflammatory signs Ultrasound: - Small solid tumor attached to the retina, well limited. - Large tumor with multifocal hyperechoic areas (calcifications). - Retinal detachment or hemorrhage.

Retinoblastoma CT: - Small tumor against the wall with or without retinal detachment. - Disseminated tumor in the vitreous. - Intense enhancement. - Calcifications : single or multiple. - Locoregional and distance extension. MRI: - Iso or T1 hyperintense, T2 hypointense. - Heterogeneous enhancement. - Extending around the eye.

Axial contrast-enhanced CT scan with a parenchymal window: The left vitreous is heterogeneous with calcifications and retinal detachment (red arrow). Enhancement with asymmetric enlargement of the left optic nerve (blue arrow). A four month old infant Left leukocoria and exophtalmos

MRI patterns. Axial T2 (A) and axial without (B) and after gadolinium injection (C) weighted MR images. An expansive retinal process into the vitreous hypointense T2, hyperintense T1, enhanced after gadolinium injection (red arrow). Asignal areas corresponding to calcifications, best seen on CT. AB C Sagittal T1 with Gadolinium weighted images. Enlargement of the left optic nerve enhanced after gadolinium injection (blue arrow).

Rhabdomyosarcome Malignant mesenchymal tumor The most common in children (6% of malignant tumors). Orbital Location: frequent. Older children : mean age> 6 years. Clinical signs: - Rapidly progressive exophthalmos with ptosis. - Pain, eyelid edema. - Mass.

CT: - Mass isodense to muscles, well limited and enhanced. - Lysis of bony walls. - Invasion of sinuses and nasal cavities and cavernous sinus. MRI: - Hypointense on T1 weighted-images. - Hyperintense on T2 weighted patterns. - Moderate to intense enhancement. - Periorbital Extensions: - Extension to sinuses and meninges: Changes the stage of the tumor and thus the therapeutic management and the prognosis.

Axial contrast-enhanced CT scan with a parenchymal (A) and a bone (B) window: Mass isodense to muscles, well limited and enhanced (red arrow). Lysis of the external bony walls (blue arrow). A one year old infant Exophtalmos and Inflammatory signs A B

MRI patterns. Axial T2 (A) and axial T1 before (B) and after gadolinium injection (C) weighted MR images. Mass hyperintense on T2 and isointense on T1 to muscles, well limited and highly enhanced (red arrow). Periorbital extension and to the meninges (blue arrow). A BC

Capillary hemangioma Benign vascular tumor due to a proliferation of the vascular endothelium. The second most common benign tumor in children after the dermoid cyst Evolution usually to a spontaneous regression Treatment: - Therapeutic abstention in the simple forms - Surgical indications in the large shapesinfiltrating the visual axis

Capillary hemangioma CT: - Isodense mass. - Intense and homogeneous contrast enhancement. - No bone abnormalities. MRI: - Mass with punctate hyposignal corresponding to blood flow ("signal void") in the capillaries. - Intermediate signal on T1 between the muscle and the fat. - Hyperintense on T2. - Marked enhancement.

MRI patterns. Axial T2 (A), sagittal T1 (B) and coronal T1 after gadolinium injection (C) weighted MR images. Orbital mass with punctate hyposignal corresponding to blood flow ("signal void") in the capillaries (red arrow), markedly enhanced (blue arrow). A B C 6 months later, MRI patterns. Axial T2 (A) and axial T1 after gadolinium injection (B) weighted MR images. The mass decreased. A six month old infant. Right exophtalmos and ptosis AB

Optic nerve glioma Glioma in children: benign tumor often part of a known neurofibromatosis (NF1). Between 5 and 10 years There is aggressive forms that give metastases Clinical signs - Unilateral decrease in the visual acuity. - Strabismus or nystagmus. - Exophthalmos.

Optic nerve glioma CT: - Large optic nerve isodense to gray matter. - Cystic areas. - Enlargement of the optic canal. - Enhancement various. MRI: - Iso-intense on T1, hyperintense on T2 - Marked enhancement - Extension: chiasmal and retro-chiasmatic damage. - To link to an NF1: characteristics of the disease: the basal ganglia are hyperintenses.

A three year old infant Left exophtalmos and a decrease in the left visual acuity CT: enlargement of the optic nerve with cystic areas A CB MRI patterns. Axial T1 (A), coronal T2 (B) and axial T1 after gadolinium injection (C) weighted MR images. Iso-intense on T1, hyperintense on T2 markedly enhanced.

Dermoid and epidermoid cysts Location: Medial corner of the eye Frequent component fatty (dermoid cyst) CT: -Mass well circumscribed hypodense, -may contain calcifications and fat (dermoid) -liquid: (epidermoid) MRI: -Hyperintense on T2 -On T1: hyperintense (dermoid) and hypointense (epidermoid) -Unenhanced

A BC D MRI patterns. Axial T1 (A), T2 (B). Coronal (C) and axial (D) T1 after gadolinium injection weighted MR images. A dermoid cystic located at the medial corner of the left orbit: fading on the T1 fat sat sequence, hyperintense on T2 and unenhanced.

Histiocytosis X Due to a proliferation of Langerhans cells Before the age of 10 Orbital damage: 10% of histiocytosis Clinical signs: - Asymptomatic - Unilateral Exophthalmos - Bilateral exophthalmos

Histiocytosis X CT: - Osteolytic mass with well defined outlines isodense to soft tissue. - No enhancement. - Sometimes, of bone defect with regular outlines containing a sequestrum. MRI: - Heterogeneous signal on T1. - Hyperintense on T2. - Indispensable if intracranial extension.

Coronal (A) and axial (B) contrast-enhanced CT scan with a parenchymal window. Coronal (C) CT with a bone window. Osteolytic mass with well defined outlines (red arrow). A bone defect with regular outlines (blue arrow). A B C

MRI Axial T1 (A), coronal T2 (B). Axial T1 after gadolinium injection (C) weighted MR images. Hypointense signal on T1, hyperintense on T2. High enhanced mass. A B C

Orbital metastasis Clinical signs: nonspecific Preferential localization site : oculomotor muscles, the optic nerve, choroid and greater wing of sphenoid. Neuroblastoma: - 8 to 20% of cases of orbital metastases. - Between 2 and 5 years. - Bilateral: 40% of cases. Ewing sarcoma: - Aged child or adolescent Nephroblastoma: - Very rarely the cause of orbital metastasis

Orbital metastasis CT: - Mass at the oculomotor muscle, localized, homogeneous and enhanced. - Osteolysis spiculation or thickening of the roof or floor of the orbit. - Sometimes intratumoral calcifications. MRI: - Signal may vary depending on the nature or cystic areas. - Rarely enhanced.

Axial (A) and sagittal (B) CT scan with a bone window. Sagittal (C) and coronal (D) contrast-enhanced CT scan with a parenchymal window Mass localized at the external orbital wall: homogeneous and enhanced (red arrow). Osteolysis spiculation on the external orbital wall (blue arrow). Axial contrast-enhanced CT scan with a parenchymal window. Abdominal mass: Neuroblastoma A B C D

Conclusion The tumor exophthalmos is a common clinical signs in children. Several causes are found. Imaging CT and MRI in our particular context, can lead to the diagnosis and help therapeutic management. MRI is a great help when it is available.