Imaging General imaging features Imaging studies show thinning of the sclera with focal bulge. May be unilateral or bilateral. Computed tomography features Computed tomography (CT) shows bulging of posterior aspect of the globe away from optic disc, usually on the temporal aspect. Scleral thinning is associated with focal bulge. May see associated retinal or choroidal detachment, with or without hemorrhage. Magnetic resonance imaging features Magnetic resonance…

Imaging Magnetic resonance imaging (MRI) has the unique ability to characterize hemorrhage using hemoglobin’s paramagnetic qualities and makes it ideally suited to evaluate VLM. MRI clearly demonstrates the internal structure of subacute and chronic hemorrhagic cysts based on paramagnetic qualities. MRI may detect “flow voids” from large feeding vessels not appreciated by computed tomography (CT). Computed tomography features A soft, bulky, nonencapsulated infiltrative tumor of mixed…

Key points Definition: Orbital venous varix (OVV) is a rare intraorbital vascular malformation composed of single or multiple venous channels that may enlarge intermittently with changes in venous pressure. Synonym: Orbital venous malformation. Classic clue: Patients present with enophthalmos or acute intraorbital hemorrhage and are found to have a mass causing painful proptosis aggravated by head down position, coughing, sneezing, or Valsalva maneuver. OVVs may be…

Key points Definition: Cavernous sinus thrombosis (CST) is a potentially life-threatening complication usually secondary to infection, commonly coming from nose, sinuses, ears, or teeth. Synonyms: Cavernous sinus thrombophlebitis, septic cavernous sinus thrombosis. Classic clue: Patient presents with recent-onset HA, photophobia, periorbital edema, proptosis, ophthalmoplegia, and vision loss demonstrating dilated superior ophthalmic vein (SOV) and cavernous sinus (CS) thrombi. As with other rare entities, misdiagnosis is common.…

Key points Definition: Carotid-cavernous fistula (CCF) is an abnormal connection between the carotid artery and/or its branches and the cavernous sinus (CS). Classic clue: Patient presents with an acute onset of Dandy’s triad with pulsatile proptosis, chemosis, and bruit accompanied by pain and progressive visual loss. Initial computed tomography (CT) or magnetic resonance imaging (MRI) shows enlarged CS and superior ophthalmic vein (SOV) followed by CT…

Key points Definition: Congenital anophthalmia (CA) is a rare malformation causing unilateral, or bilateral eye absence. Classic clue: Anophthalmia is discovered at delivery and frequently found by fetal ultrasound (US). Anophthalmia is the medical term for absence of eyes coming from the Greek meaning “without eye.” CA arises as a consequence of damage to developing eye(s) during first 8 weeks of fetal development. , Imaging Computed…

Key points Definition: Congenital orbital teratomas (COTs) are rare tumors. They are usually benign, complex masses with cystic and solid components containing a mixture of fat, calcium, and bone. Synonyms: Orbital teratomas, teratomas. Classic clue: Huge orbital mass containing cystic and solid components, displacing and deforming the globe in young children with a complex, bizarre imaging appearance suggesting multiple tissue types. COTs are characteristically massive, causing…

Key points Definition: Pathologic entity caused by abnormal hypertrophy of the ocular hyaloid system. Classic clue: Child presenting at or soon after birth with leukocoria, micropthalmia, fluid-fluid level, no calcifications, and persistent Cloquet’s canal is virtually pathognomonic. In normal embryologic development, the primary vitreous is replaced by the adult secondary vitreous and does not normally hypertrophy or persist to infancy or childhood. Persistent hyperplastic primary vitreous…

Key points Definition: A coloboma is caused by a rare congenital defect with failure of the embryonic intraocular fissure to fuse during the first trimester of fetal development resulting in an elongated or malformed globe. Colobomas may arise in any part of the globe along the course of the uveal tract and may include iris, ciliary body, choroid, and optic nerve. Synonyms: Optic disc coloboma, coloboma…

Key points Definition: Rhabdomyosarcoma (RMS) is a relatively rare sarcoma, frequently found in children aged between 1 and 5 years. Classic clue: A 5-year-old old child is referred by a pediatrician with a history of possible recent trauma, developing rapid onset unilateral proptosis, globe displacement, and showing a mass isodense and isointense to muscle on computed tomography (CT) and T1 magnetic resonance imaging (MRI), hyperintense on…

Key points Definition: Esthesioneuroblastoma (ENB) is a rare neuroendocrine malignancy of neural crest origin arising from olfactory epithelium near the cribriform plate and the nearby nasal cavity. ENB may invade the orbit, causing ophthalmic signs and symptoms. Synonym: Olfactory neuroblastoma. Classic clue: The patient presents with many months of nonspecific symptoms, including stuffy nose, epistaxis, rhinorrhea, anosmia, headache, facial pain, diplopia, or proptosis. , Classically found…

Key points Definition: Isolated metastasis to the optic nerve is rare and is often overlooked or misdiagnosed initially. Classic clue: Typically, a middle-aged female presents with “a little blurred vision,” further inquiry identifies pain, proptosis, reduced visual acuity, and bitemporal hemianopsia with enhancing abnormality related to the optic nerve (ON) sheath(s). Her past medical history reveals that she first had breast carcinoma 10 years ago with…

Key points Definition: Leukemia presenting as an orbital mass portends a more serious prognosis as these patients continue to show significantly lower survival rates than other leukemia patients. Synonym: A subset of orbital leukemia includes: granulocytic sarcoma, chloroma, or myeloid sarcoma. Classic clue: An 8-year-old presenting with a sensation of fullness, double vision, and proptosis has a homogeneous extraconal mass that molds to orbital wall without…

Key points Definition: Retinoblastoma (RB) is a rapidly developing intraocular cancer arising from immature retinal cells. Classic clue: A calcified posterior globe mass in an infant or young child is an RB until proved otherwise. RB is the most common intraocular tumor in children; 95% of cases are in children under 5 years. , The most common and obvious sign of RB is leukocoria, also known…

Key points Definition : Ocular melanoma is the most common intraocular malignancy in adults. Synonyms : Orbital melanoma, uveal melanoma, choroidal melanoma. Classic clue: A “collar button” enhancing intraocular mass in adults. Computed tomography (CT) shows: Ocular melanoma is hyperdense. Ocular melanoma has moderate contrast enhancement. Magnetic resonance imaging (MRI) shows: T1 bright (most). T2 dark. T1 + Gd moderate enhancement. Imaging computed tomography Features Precontrast…

Key points Definition: Ocular adnexal lymphoma (OAL) is one of the most common orbital tumors in adults, accounting for 50% of orbital malignancies. Synonym: Orbital lymphoma (OL). Classic clue: An older patient presenting with an orbital mass causing progressive exophthalmos, ptosis, diplopia and restricted ocular movement. Imaging shows restricted diffusion with the “apparent diffusion coefficient (ADC) black hole sign.” Imaging Computed tomography features Neurological examination computed…

Key points Definition: Usually found in middle-aged adults, orbital schwannomas (OS) are well-defined, encapsulated, slowly growing benign tumors arising from peripheral nerve Schwann cells, and comprise 1% to 2% of orbital tumors. Classic clue: Middle-aged patient presenting with optic neuropathy, proptosis, or diplopia with a well- circumscribed retrobulbar intraorbital mass separate from the optic nerve (ON) which on dynamic magnetic resonance imaging (MRI) shows enhancement progressing…

Key points Definition: Orbital lipomas (OL) are very rare tumors that are usually benign, accounting for less than 1% of orbital tumors. Classic clue: The patient presents with a well-circumscribed homogeneous orbital mass with low attenuation approximating orbital fat, having no calcifications or fluid-fluid level suggestive of a dermoid or teratoma. True primary OLs are as uncommon as extraorbital lipomas are common. While usually having a…

Key points Definition: Dermoids originate from totipotential germ cells. Present at birth, these differentiate abnormally, developing characteristics of mature dermal cells. Synonym: Orbital dermoids, retrobulbar orbital dermoids, or deep dermoids. Classic clue: Well-circumscribed encapsulated mass with low Hounsfield numbers, filled with high T1 signal material. Displacement of globe and ocular muscles may impair ocular motility. Compression of the optic nerve (ON) may result in visual impairment.…

Key points Definition: Optic nerve meningioma (ONM) is a rare, benign tumor arising from arachnoid cap cells in meninges covering the optic nerve (ON). Synonym: Optic nerve sheath meningioma (ONSM). Classic Clue: Appears as an enhancing mass surrounding the nonenhancing ON with “tram track” calcifications and perioptic cysts. The second most common ON tumor. Calcification is a characteristic feature on computed tomography (CT). Main differential diagnosis…