Orbits

• Structural/Congenital

  • Staphyloma

    • Outward bulging of the posterior globe on the temporal side of optic nerve

  • Coloboma

    • Congenital defect in any ocular structure

  • Astrocytic glial hamartomas

    • Can be seen in TS, NF, and vHL

    • Calcifications on retina

    • DiffDx: retinoblastoma

• Ocular infection

  • Toxocara canis

• Ocular lesions

  • Retinoblastoma

    • Calcifications in the posterior portion of the globe with extension into vitreous

    • Moderately bright on T1WI and dark on T2WI

  • Persistent hyperplastic primary vitreous

    • Funneled shaped mass (Cloquet canal) between back of the lens and head of optic nerve

    • Microphthalmia

    • Does not calcify

  • Coats disease

    • Telangiectatic vessels leaking serum and protein into retina and subretinal space

    • High density of the vitreous due to exudate

    • Bright on T1WI and bright on T2WI

    • DiffDx: retinoblastoma (dark on T2WI)

  • Toxocara canis

  • Retrolental fibroplasia => result of prolonged oxygen therapy in premature infants

    • Increased density of posteior portion of the globe

  • Melanoma

    • Hyperdense

    • Bright on T1WI, dark on T2WI

  • Choroidal hemangioma

  • Medulloepithelioma

  • Metastases

  • Choroidal osteoma

• Intraconal

  • Optic nerve lesions

    • Glioma, meningioma, schwannoma, hemangioblastoma, neuritis, sarcoid

    • Devic disease => optic neuritis associated with transverse myelitis

  • Tolosa-Hunt syndrome => painful ophthalmoplegia caused by nonspecific inflammation of the cavernous sinus or superior orbital fissure.

  • Optic nerve glioma

    • Radiographically, can not be separated from the nerve

    • Arachnoidal granulamatosis (perineural glial proliferation) => a feature of optic gliomas in neurofibromatosis

  • Optic nerve sheath meningioma

    • Nerve may be visualized

  • Cavernous/capillary hemangioma

  • Orbital venous anomalies

    • Orbital varix

    • Lymphangioma

  • Carotid-cavernous fistula

  • Dural vascular malformation

• Conal

  • Thyroid ophthalmopathy

    • Inferior and medial rectus are most commonly affected

    • Most common single pattern is enlargement of all muscles

  • Orbital pseudotumor (Tolosa-Hunt syndrome)

  • Sarcoidosis

  • Wegener's granulomatosis

    • Homogenously enhancing mass with associated sinus disease and bone destruction

  • Kimura disease

    • Similar to orbital pseudotumor but with skin findings in young Asian males

  • Orbital lymphoma

    • Molds around the orbit

    • DiffDx: pseudotumor

  • Posttransplantation lymphoproliferative disorder

    • Can destroy bone

• Extraconal lesions

  • Infection

  • Lacrimal sac lesions

    • Dacryocystitis

    • Papilloma - has malignant degeneration potential

  • Lacrimal gland lesions

    • Mikulitz syndrome => non-specific swelling of lacrimal and salivary glands associated with sarcoid, TB and leukemia.

    • Sjogren's syndrome => lymphocytic infiltration of lacrimal and salivary glands associated with connective tissue disorders

    • Lymphoid tumors (usually does not produce bony erosion)

    • Epithelial tumors (generally involve bone)

      • Pleomorphic adenomas

      • Malignant adenoid cystic carcinoma

    • Transitional cell carcinoma

  • Dermoids

  • Orbital rhabdomyosarcoma

  • Lymphangioma

  • Fibrous histiocytoma

  • Metastasis

    • Scirrhous breast carcinoma => infiltrative retrobulbar mass with enophthalmos from desmoplastic reaction

  • Sphenoid wing meningioma

    • DiffDx: fibrosseous lesions such as ossifying fibroma, osteoma, sclerotic metastases such as prostate metastases, fibrous dysplasia

  • Bone lesions

    • Fibrous dysplasia

    • Paget's

    • EG

    • Fibroosseous lesions

      • Osteoma

      • Ossifying fibroma

      • Osteoblastoma

      • Osteosarcoma

      • Osteoclastoma

      • Brown tumor of hyperparathyoidism

      • ABC

      • Giant cell reparative granuloma

        • Probably a reaction to intraosseous hemorrhage

        • May contain fluid levels

Nasal region

• Prenasal mass

  • Dermoid/epidermoid cyst

  • Encephalocele

  • Hemangioma

  • Glial heterotopia

Mandible

• Cystic masses

  • Odontogenic cysts

    • Radicular cyst

    • Dentigerous cyst

      • Formed by excessive accumulation of fluid between enamel and dental capsule

      • Well corticated pericoronal radiolucency

    • Odontogenic keratocyst

      • Aggressive cystic jaw lesion

        • Perforation of bone cortex

        • Scalloped corticated border

        • Large size

      • Associated with basal nevus syndrome

    • Botryoid cyst => developmental lateral periodontal cyst

  • Non-odontogenic cyst

    • Solitary simple hemorrhagic bone cyst

    • Static bone cavity => Stafne cyst

• Benign tumors

  • Ameloblastoma

  • Odontoma

  • Fibromyxoma

  • Cementoma

• Malignant tumors

  • Odontogenic

    • Odontogenic carcinoma

    • Odontogenic sarcoma

  • Non-odontogenic

    • Osteosarcoma

    • Chondrosarcoma

    • Ewing's sarcoma

    • Multiple myeloma

  • Metastases

    • Carcinoma (breast, lung, renal)

    • Sarcoma

Ear/Temporal Bone

• Middle Ear
  • Anatomy
  • Malleus
  • Manubrium
  • Neck
  • Anterior process
  • Head
  • Incus
  • Body
  • Long process
  • Lenticular process
  • Short process
  • Stapes
  • Head
  • Neck
  • Anterior crus
  • Posterior crus
  • Footplate
  • Developmental
  • Bony bars
  • Oval window atresia
  • Fenestral otospongiosis
  • Inflammatory
  • Cholesteatoma
  • Acquired from perforation of tympanic membrane
  • Congenital from epidermoid formation
  • Tympanosclerosis
  • Resorptive osteitis
  • Masses
  • Benign
    • Hemangioma - most common benign mass in pediatric patients
    • Facial nerve neuroma
    • Paraganglioma - most common benign mass in adult patients
    • Cholesterol granuloma
  • Malignant
    • Squamous cell carcinoma
  • Trauma
  • Fractures
  • Dislocations
    • Incus is most common

• CPA

  • Schwannoma

  • Arachnoid cyst

  • Meningioma

  • Epidermoid

• Petrous Apex

  • Mucocele

  • Cholesterol granuloma

  • Multiple myeloma

  • Metastasis

  • Schwannoma

  • Enchondroma/Chondrosarcoma

  • Apical petrositis

  • Xanthoma