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Key points Definition: Fibrous dysplasia (FD) is typically a benign slowly progressing tumorlike process involving bone maturation in which normal cancellous bone is replaced by immature woven bone and fibrous tissue. Its predilection for the skull can cause serious orbital problems. Synonym: Lichtenstein-Jaffe disease. Classic clue: Preadolescent patient presents with painless proptosis and diplopia caused by an expanding enhancing sphenoid wing mass showing intact bony cortex.…

Key points Definition: Plasma cell tumors may present as a solitary bone plasmacytoma (SBP), extramedullary plasmacytoma (EMP), or multiple myeloma (MM). While orbital involvement is rare and may not be associated with MM at presentation, it habitually heralds the unwelcome unleashing of this formidable foe (see Figure 49-3 , C ). Synonyms: Solitary bone plasmacytoma (SBP), solitary extramedullary plasmacytoma (SEP). Classic clue: a 60-year-old man presents…

Key points Definition: Wegener granulomatosis (WG) is a systemic vasculitis causing necrosis and granulomatous inflammation, often presenting with a “runny nose.” Without modern treatment, most patients would quickly progress to death within a few short months. Synonym: granulomatosis with polyangiitis. Classic clue: Middle-aged Caucasian, sent for sinus examination for a “runny nose,” is found to have a medial orbital mass in addition to adjacent ethmoid sinus…

Key points Definition: Pseudotumor cerebri (PTC) is a clinical entity characterized by intracranial hypertension in patients without other demonstrable intracranial disease, including but not limited to primary or secondary neoplasm. Synonyms: idiopathic intracranial hypertension, benign intracranial hypertension. Classic clue: Obese female of childbearing age with diplopia, headache (HA), nausea, vomiting, and pulsatile tinnitus. Physical examination proves papilledema, visual field cuts, and cranial nerve (CN) VI palsy.…

Key points Definition: Pott’s puffy tumor is an osteomyelitis with associated subperiosteal abscess collection usually related to frontal sinusitis or mastoiditis. It may extend into the orbit causing inflammation including cellulitis, subperiosteal abscess, orbital abscess (OA), and cavernous sinus thrombosis. It poses a potentially life-threatening emergency, often requiring surgery. Synonym: Pott puffy tumor. Classic clue: Teenage boy presents with slow saga of recurrent headache, fever, and…

Key points Definition: Cytomegalovirus retinitis (CMVR) is an opportunistic infection that untreated leads to progressive retinal destruction and blindness. Synonym: CMV uveitis Classic clue: AIDS patient presenting with blurred vision, floaters, and blind spots found to have abnormal retinal thickening and enhancement with abnormal signal in the posterior chamber. CMV is a DNA virus from the herpesvirus group, also known as human herpesvirus 5 (HHV-5). ,…

Key points Definition: Orbital abscess (OA) is an intraorbital collection of neutrophils and microorganisms that has become a sight-threatening and potentially life-threatening emergency, requiring prompt imaging and treatment. Classic clue: Patient presenting with recent onset severe proptosis, complete ophthalmoplegia, and vision loss with retroorbital extraconal mass exhibiting “ring” enhancement and intraorbital air. The associated inflammatory response is a defensive reaction to prevent the spread of the…

Key points Definition: Squamous cell carcinoma (SCC) of the lacrimal sac is an uncommon but deadly cause of abnormal unilateral tearing, which when not promptly diagnosed and treated can lead to local invasion and death. Classic clue: A patient presents with unilateral epiphora (uncontrolled tearing with tears overflowing onto the face), recurrent dacryocystitis, and imaging showing a lacrimal sac mass. Imaging Computed tomography features Computed tomography…

Key points Definition: Adenoid cystic carcinoma of the lacrimal gland (ACC LG) is a rare form of adenocarcinoma causing an extraconal, unencapsulated malignancy, usually arising from the lacrimal gland’s orbital lobe. Synonym: cylindroma. Classic clue: A middle aged woman presents with diplopia, proptosis, pain, and paresthesia. An unencapsulated, irregular, ovoid, soft tissue lacrimal fossa mass is evident resulting in inferiomedial globe displacement with a heterogeneous T2…

Key points Definition: Lacrimal gland dermoids (LGDs) represent congenital, non-neoplastic choristomas, containing cytologically normal tissue not normally found at that location. Synonym: anterior orbital dermoid (AOD). Classic clue: Young child presents with smooth scalloping of orbital wall by adjacent unilateral lacrimal-gland mass having hyperdense wall, decreased attenuation center, increased T1 signal intensity, and no postcontrast enhancement. Imaging Computed tomography features LGDs are typically unilateral well-defined cyst-like…

Key points Definition: Malignant lymphoma of the lacrimal gland is relatively rare and is more prevalent in elderly women. Synonym: Primary lacrimal gland lymphoma. Classic clue: Patient presents with painless proptosis, showing nearly symmetrical bilateral lacrimal gland enlargement with smooth, homogeneous, diffuse enhancement and restricted diffusion. Despite being rare, lymphomas comprise 37% of lacrimal gland malignancies. Imaging Computed tomography features Bilateral lacrimal gland enlargement is isodense…

Key points Definition: Bilateral lacrimal gland enlargement secondary to sarcoidosis, a systemic idiopathic inflammatory granulomatous disease. Classic clue: Bilateral lacrimal gland enlargement in a patient with “dry-eye” symptoms and known (or findings consistent with) sarcoidosis. Despite decades of delving into this dire disease, its etiology remains unknown. Sarcoid’s ocular and orbital emergence may precede by decades the development of systemic symptoms. , Important for radiologists to…

Key points Definition: Infiltration of the optic nerve (ON) is a rare entity important to recognize in patients with leukemia, as early diagnosis and treatment are the only hope for prevention of blindness. Synonym: ON infiltration by leukemia. Classic clue: Enlarged ON with avid enhancement in patient with orbital discomfort and rapidly deteriorating vision. ON involved in 13% to 18% of all leukemic types. , Diagnosis…

Key points Definition: Optic nerve neuritis (ONN) is inflammation of the optic nerve (ON), which may cause sudden painful, partial or complete visual loss, for a variety of reasons. Classic clue: Young woman presenting with painful eye movement, decreased visual acuity showing enlarged, enhancing ON, and periventricular white matter lesions suggesting multiple sclerosis (MS). ONN usually develops in association with an autoimmune disorder, which may be…

Key points Definition: Idiopathic orbital pseudotumor (IOP) is a nonmalignant, nongranulomatous extraocular orbital and adnexal space-occupying lesion simulating neoplasm without associated local or systemic etiology. Synonyms: Idiopathic orbital inflammation (IOI), idiopathic orbital inflammatory disease, nonspecific orbital inflammation (NSOI). Classic clue: 45-year-old female presents with pain, proptosis, periorbital swelling, and decreased vision in one or both eyes. Imaging shows poorly circumscribed enhancing intraorbital soft tissue mass. Most…

Key points Definition: An autoimmune inflammatory disorder affecting the orbit with leukocytic infiltration causing erythema, edema, conjunctivitis, and upper lid retraction. Synonyms: Graves ophthalmopathy, thyroid orbitopathy, thyroid eye disease (TED), thyroid associated orbitopathy (TAO). Classic clue: Bilateral extraocular muscle (EOM) enlargement sparing tendinous insertions, with increased retroorbital fat and exophthalmos. Most common cause of proptosis in adults. Compression of optic nerve (ON) may cause optic neuropathy.…

Key points Definition: Optic disc drusen (ODD) are tiny yellow or white globules of hyaline-like material deposited on or below the surface of the optic disc, which progressively calcify producing visual field defects. Also known as optic nerve head drusen (ONHD), disc hyaline bodies, pseudopapilledema, pseudoneuritis, buried disc drusen, and congenitally elevated or anomalous discs. Classic clue: Small sharply circumscribed dense calcification at one or more…

Key points Definition: Cataracts cloud the normally clear ocular lens, block the passage of light to the retina, and cause decreased vision and blindness if untreated. Classic clue: An elderly patient who complains of night “glare” and decreasing vision, with a well-defined biconvex calcified disc posterior to the cornea on computed tomography (CT). It may also be a patient of any age who has received trauma…