Pleomorphic adenoma

Pleomorphic adenoma (also known as benign mixed tumor) is the most common tumor of the major salivary glands, and the most common benign tumor of the parotid glands (~75% of all benign salivary gland tumors). Prior head and neck irradiation is a risk factor. They are typically solitary, slowly growing, and asymptomatic. They are typically diagnosed after palpation by the patient or incidentally on imaging studies. Surgical resection is advised due to risk of malignant transformation.

On MRI, pleomorphic adenomas, have polylobulated margins a rim of low T2 signal corresponding to a fibrous capsule. They have heterogeneous low-to-intermediate signal intensity on T1-weighted images. High T2 signal and avid, solid enhancement are considered relatively specific features, especially when present in a younger patient (< 57 years). Dynamic contrast-enhanced (DCE) MRI shows gradual enhancement. On diffusion-weighted imaging (DWI), pleomorphic adenomas tend to have very high ADC values; however, DWI is not able to differentiate between benign and malignant parotid gland tumors.

On ultrasound, pleomorphic adenomas are typically hypoechogenic. They can have mild to moderate uptake on FDG PET.

Differential considerations include:

• Warthin tumor: 10–15% are bilateral. Can have proteinaceous cystic components with high T1 signal ranging from a few millimeters to 1–2 cm. Solid components have rapid enhancement and washout.
• Adenoid cystic carcinoma: Small, low-grade lesions can be mistaken for pleomorphic adenomas. Variable signal intensity on T2-weighted depending on type. Low-grade tumors have high T2 signal in the solid parts. Large tumors can have cystic areas of hemorrhagic necrosis.
• Myoepithelial adenoma: Also tend to have very high ADC values
• Basal cell adenoma: More commonly in the superficial lobe of the parotid gland. Tend to be round and well-circumscribed tumors. Have heterogeneous enhancement on CT.
• Carcinoma in pre-existing pleomorphic adenoma (carcinoma ex pleomorphic adenoma): Typically less well-circumscribed than benign pleomorphic adenoma. Tends to occur after 10–15 years of an existing pleomorphic adenoma, with sudden rapid growth (3–6 months) in patients in the sixth-to-eighth decades of life.
• Lymphoma: Tend to be multiple. Can have well-defined and lobulated margins. Tend to have low T2 signal and slight enhancement.
• Sarcoid: Can be placed in any differential, including this one.

References

• Christe A, Waldherr C, Hallett R, Zbaeren P, Thoeny H. MR imaging of parotid tumors: typical lesion characteristics in MR imaging improve discrimination between benign and malignant disease. AJNR Am J Neuroradiol. 2011 Aug;32(7):1202-7.
• Habermann CR, Arndt C, Graessner J, Diestel L, Petersen KU, Reitmeier F, Ussmueller JO, Adam G, Jaehne M. Diffusion-weighted echo-planar MR imaging of primary parotid gland tumors: is a prediction of different histologic subtypes possible? AJNR Am J Neuroradiol. 2009 Mar;30(3):591-6.
• Heaton CM, Chazen JL, van Zante A, Glastonbury CM, Kezirian EJ, Eisele DW. Pleomorphic adenoma of the major salivary glands: diagnostic utility of FNAB and MRI. Laryngoscope. 2013 Dec;123(12):3056-60.
• Kato H, Kanematsu M, Watanabe H, Kajita K, Mizuta K, Aoki M, Okuaki T. Perfusion imaging of parotid gland tumours: usefulness of arterial spin labeling for differentiating Warthin's tumours. Eur Radiol. 2015 Nov;25(11):3247-54.
• Kato H, Kanematsu M, Mizuta K, Ito Y, Hirose Y. Carcinoma ex pleomorphic adenoma of the parotid gland: radiologic-pathologic correlation with MR imaging including diffusion-weighted imaging. AJNR Am J Neuroradiol. 2008 May;29(5):865-7.
• Okahara M, Kiyosue H, Hori Y, Matsumoto A, Mori H, Yokoyama S. Parotid tumors: MR imaging with pathological correlation. Eur Radiol. 2003 Dec;13 Suppl 4:L25-33.

Radiation-Associated Sarcomas

Patient with history of radiation therapy for head and neck cancer. Radiation field extended into the supraclavicular nodal stations. CT shows an osteoid producing soft tissue mass to the right of midline. Bone scan and PET show uptake in the lesion, as well as contralateral lymph nodes. PET shows an FDG-avid lung nodule. T1-WI post-contrast MRI with FS shows a peripherally enhancing soft tissue mass.

The incidence of radiation-associated sarcomas of bone and soft tissue is about 0.1%. They are more commonly seen in patients with breast cancer, lymphoma, head and neck malignancies, and gynecologic cancers. The distribution of primary cancers is likely related to the larger numbers of patients with these cancers and the high survival rates for these tumors.

The majority of radiation-associated tumors are soft tissue sarcomas, with bone sarcomas making up about 20-30% of cases. The majority are high grade and aggressive. The most common soft tissue sarcomas are unclassified pleomorphic sarcoma (UPS, formerly MFH), followed by angiosarcoma (particularly in breast cancer), fibrosarcoma and leiomyosarcoma (particularly in retinoblastoma). The most common bone sarcomas are osteosarcomas.

The latency between radiation and sarcoma ranges from as little as a few months to 54 years. The average is 7 to 16 years. In breast cancer, the average is 10 to 11 years (4-8 years for angiosarcomas). In childhood cancers, the average latency is between 12 to 13 years.

Risk factors include, dose (Rarely seen with low doses: <40 Gy), age at exposure, concomittant chemo exposure (particularly alkylating agents) and genetic tendency (e.g., Li-Fraumeni syndrome).

References

Maki, R. et al. Radiation-Associated Sarcomas. UpToDate

The Lamina Dura

The lamina dura is the bony lining of the socket (alveolus) of a tooth. The periodontal ligaments extend from the lamina dura to the cementum of the tooth, an keep the tooth in place. The lamina dura is cribriform plate produced by the periodontal ligament and fibers of the periodontal ligament are embedded within it.

While loss of the lamina dura (arrow in image above) is sometimes said to be pathognomonic for hyperparathyroidism, it can be seen in a wide range of conditions:

• Hyperparathyroidism: The case above is from a patient with primary hyperparathyroidism.
• Osteomalacia
• Osteoporosis
• Paget disease
• Leukemia
• Myelomatosis
• Cushing disease

The lamina dura can be thickened in bisphosphonate-related osteonecrosis of jaw (BRONJ)

References

• Arce K, Assael LA, Weissman JL, Markiewicz MR. Imaging findings in bisphosphonate-related osteonecrosis of jaws. J Oral Maxillofac Surg. 2009 May;67(5 Suppl):75-84.
• Berry HM Jr. The lore and the lure o' the lamina dura. Radiology. 1973 Dec;109(3):525-8.

Bisphosphonate-related Osteonecrosis of the Jaw

Figure 1: Axial CT of the facial bones. There is a mixed sclerotic and lytic lesion within the mandible (Figure 1, arrows) with foci of cortical interruption (Figure 2, arrowheads). 

Figure 2: Sagital CT of the facial bones. There is a mixed sclerotic and lytic lesion within the mandible (Figure 1, arrows) with foci of cortical interruption (Figure 2, arrowheads).

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is associated with the use of bisphosphonates to treat severe osteoporosis, and metabolic and oncologic bone conditions, including hypercalcemia associated with malignancy. These agents inhibit osteoclasts, reducing bone resorption and osteolysis, and also possess antiangiogenic properties, reducing blood flow and necrosis. Patients with BRONJ present with pain and exposed, nonvital bone involving the maxillofacial structures. The incidence of BRONJ increases with the duration of treatment, especially with the intravenous route and concomitant steroid therapy. The osteonecrosis usually is participated by dental extraction. When spontaneous, it commonly occurs along the mylohyoid ridge. BRONJ can mimic osteomyelitis and osteoradionecrosis. A history of dental caries and the presence of periosteal elevation can help direct one towards the diagnosis of osteomyelitis. Osteoradionecrosis can be excluded if the patient has not received oropharyngeal radiation therapy. Jaw neoplasm, primary or metastatic, can potentially also mimic BRONJ. Treatment of BRONJ consists of cessation of bisphosphonate drug therapy, antibiotics for secondary infection, and surgical debridement of necrotic sequestra.

References:

• Am Fam Physician. 2012 Jun 15;85(12):1134-114
• RadioGraphics 2009; 29:1971–1986 
• AJNR June 2007 28: 139-1145

Patterns of Lymphatic Drainage of the Paranasal Sinuses

Sinus	Lymphatic Drainage
Frontal	Submandibular (level IB)
Ethmoid	Submandibular (level IB)
Maxillary: Main	Lateral retropharyngeal and internal jugular (levels II, III, and IV)
Maxillary: Lateral antrum	Submandibular (level IB)
Sphenoid	Lateral retropharyngeal

References

• Som PM and Curtin HD. Chapter 2: Embryology, Anatomy, Physiology, and Imaging of the Sinonasal Cavities. in Head and Neck Imaging (5th ed.). Elsevier, 2011.
• Werner JA, Dünne AA, Myers JN. Functional anatomy of the lymphatic drainage system of the upper aerodigestive tract and its role in metastasis of squamous cell carcinoma. Head Neck. 2003 Apr;25(4):322-32.

Vagus Nerve Neurofibroma

Vagus nerve neurofibromas are very rare. They can be located in cervical or mediastinal positions. They are slowly growing and typically asymptomatic.

While the vagus nerve itself can be hard to see, knowledge of the anatomy can be helpful in localization. The vagus nerve travels from the jugular foramen in the carotid sheath between the internal jugular vein (IJ) and internal carotid artery above C4 and between the IJ and common carotid artery (CC) to the root of neck.

The case above shows a T2-hyperintense structure between the IJ and CC at the base of the neck. In this patient with neurofibromatosis, the primary consideration is a vagus nerve neurofibroma.

References

• Gilmer-Hill HS, Kline DG. Neurogenic tumors of the cervical vagus nerve: report of four cases and review of the literature. Neurosurgery. 2000 Jun;46(6):1498-503.
• Kanzaki R, Inoue M, Minami M, Sawabata N, Shintani Y, Nakagiri T, Okumura M. Bilateral mediastinal neurofibroma of the vagus nerves in a patient with neurofibromatosis type 1. Ann Thorac Cardiovasc Surg. 2013;19(4):293-6.
• Matejcik V, Steno J, Haviarova Z, Mravec B. Neurofibroma of the vagus nerve in the cervical portion. Bratisl Lek Listy. 2008;109(10):455-8.
• Sesenna E, Magri AS, Corradi D, Ferri T, Ferri A. Malignant peripheral nerve sheath tumor of the vagus nerve in a teenager with the neurofibromatosis 1 gene mutation: a case report. J Pediatr Surg. 2011 Aug;46(8):e9-12.
• Shintani Y, Ohta M, Hazama K, Minami M, Okumura M, Hirabayashi H, Matsuda H. Bilateral cervicomediastinal neurofibroma originating from the vagal nerve in a patient with von Recklinghausen's disease: report of a case. Surg Today. 2002;32(12):1068-71.

Vertebral Artery Transection

The unfortunate consequence of a rapid acceleration-deceleration injury. Sagittal image shows dissociation of the cervical spine at C6-C7. Coronal reformatted image from the CTA demonstrates loss of the right vertebral artery from it's origin to the level of C5 with presumable retrograde filling of its distal portion via collaterals. 

Killian Jamieson Diverticulum

Killian is usually mentioned when discussing the Killian's dehiscence which is the gap in the posterior hypopharynx where the muscle fibers of the cricopharyngeus muscle and inferior constrictor muscle diverge. This site is where Zenker's diverticula occur.

The Killian-Jamieson space is below the cricopharyngeus muscle and lateral to the longitudinal muscle of the esophagus. This muscular gap is the location of the rarer Killian-Jamieson diverticulum. Fluoroscopy will show an outpouching along the anterolateral esophagus inferior to the cricopharyngeus muscle (as opposed to along the posterior esophagus and superior to the cricopharyngeus muscle in the case of a Zenker's diverticulum). 

REFERENCES

Rubesin SE and Levine MS. Killian-Jamieson diverticula. AJR Am J Roentgenol 2001;177:85-9.

Open Globe Injury

CT signs of open globe injury include change in globe contour and volume, scleral discontinuity, intraocular air, and intraocular foreign body. 

NECT images above show contour deformity of the left globe with high density in the posterior chamber compatible with vitreous hemorrhage. CECT obtained several hours later (third image) shows loss of volume of the left globe. The patient was found to have a ruptured globe after sustaining a penetrating injury.

REFERENCES

Kubal WS. Imaging of orbital trauma. Radiographics 2008;28:1729-39.

Idiopathic Orbital Inflammatory Syndrome

Orbital inflammatory syndrome (OIS), also known as orbital pseudotumor, is a diagnosis of exclusion when evaluating proptosis. The typical presentation is unilateral, painful proptosis. It is categorized based on region of involvement in the orbit as either diffuse, anterior, lacrimal, myositic, and apical. 

On CECT an enhancing orbital mass is seen.  The mass is hypointense on T1WI and iso- to hyperintense on T2WI. Irregular contrast enhancement is seen with gadolinium. 

The above image demonstrates an enhancing left orbital apical pseudotumor causing proptosis. This should be differentiated from the imaging appearance of Graves Ophthalmopathy. 


REFERENCES 
Chaudhry IA, Shamsi FA, Arat YO, et al. Orbital pseudotumor: distinct diagnostic features and management. Middle East Afr J Ophthalmol 2008; 15(1):17-27.
LeBedis CA, Sakai Osamu. Nontraumatic orbital conditions: diagnosis with CT and MR imaging in the emergent setting. Radiographics 2008;28:1741-53.

Penetrating Neck Injuries

Penetrating neck injuries are usually evaluated in zones. 

• Zone I: 
• extends from the sternal notch to the cricoid cartilage
• contents - branches of the inominate artery and brachiocephalic veins, branches of subclavian arteries and veins, common carotid and vertebral arteries, trachea, esophagus, thyroid
• Zone II:
• extends from the cricoid cartilage to the angle of the mandible
• contents - common, internal, and external carotid arteries, larynx, upper esophagus, pharynx
• most commonly surgically explored
• Zone III: 
• extends from the angle of the mandible to the base of the skull
• contents - internal cartoid, vertebral, and branches of the external carotid arteries, internal jugular vein, pharynx

Due to the various vascular structures in each of the zones, CTA is often used to evaluate neck trauma. 

The above images are from a patient with bilateral penetrating neck injuries (note the subcutaneous and intramuscular emphysema). The second image shows the bifurcation of the left common carotid artery (arrowhead). In more cephlad images, the left internal carotid artery is not opacified (arrowhead, third image). Surgical exploration demonstrated a Zone II injury to the left common carotid artery as well as to the left internal jugular vein.

REFERENCES

Nunez DB, Torres-Leon M, Munera F. Vascular injuries of the neck and thoracic inlet: helical CT-angiographic correlation. Radiographics 2004;24:1087-98.

Steenburg SD, Sliker CW, Shanmuganathan K, et al. Imaging evaluation of penetrating neck injuries. Radiographics 2010;30:869-86.

Congenital Midline Nasofrontal Masses

Midline nasofrontal masses are due to faulty regression of the midface dural diverticulum during embryologic development. The differential diagnosis includes:

• Epidermoid and dermoid cysts
• dermoid  
• ectoderm + skin appendages
• usually midline and tend to occur at the glabella
• epidermoid
• ectoderm without skin appendages
• usually paramidine
• Nasal gliomas
• not a neoplasm
• cerebral heterotopia
• can be intranasal (lateral nasal wall, middle turbinate, nasal septum) or extranasal (usually at glabella, +/- overlying skin telangectasia)
• T1WI - isointense/hypointense to gray matter
• T2WI - hyperintense to gray matter
• Encephaloceles
• herniation of intracranial content through a skull defect with a persistent connection to the subarachnoid space
• high prevalence of associated intracranial abnormalities
• intracranial cysts, callosal agenesis, interhemispheric lipomas, facial clefts, schizencephaly
• usually isointense to gray matter on all MR sequences 
• may be hyperintense on T2WI due to gliosis

REFERENCES
Lowe LH, Booth TN, Joglar JM, et al. Midface anomalies in children. Radiographics 2000;20:907-22.

Cervical Spine Change in Rheumatoid Arthritis

60-80% of patients with rheumatoid arthritis have cervical spine involvement. Manifestations include:

• atlantoaxial subluxation - do flexion/extension films, increased atlantodens interval
• multilevel, "stepladder" subluxations may be seen
• erosion of the dens
• calcified pannus around the dens is NOT rheumatoid arthritis - usually CPPD
• cranial settling - decreased distance from occiput to C2
• due to facet joint erosions
• spinous process erosions
• erosions at the foramen of Luschka

REFERENCES 
Sommer OJ, Kladosek A, Weiler V, et al. Rheumatoid arthritis: a practical guide to state-of-the-art imaging, image interpretation, and clinical implications. Radiographics 2005;25:381-98.

Tonsilloliths

Tonsilloliths are stones that form in the crypts of the palatal tonsils. Most patients with tonsilloliths are asymptomatic and the finding is made incidentally, as in the patient above (multiple coarse calcifications in the bilateral tonsils). However, large tonsilloliths may cause obstruction leading to infection with possible abscess formation. Thus, the presence of tonsilloliths, even if incidental, should be reported.


REFERENCES
Mody RN and Srivastava S. Bilateral multiple tonsilloliths. Oral Radiology 2009;25(1):67-70.

Tumors Identified via Selective Catheterization of the External Carotid Artery

1. Juvenile nasopharyngeal angiofibroma:

• young boys presenting with epistaxis 
• vascular hamartoma
• embolization is therapeutic

2. Carotid body paraganglioma:

• found at the bifurcation of the carotid artery where they splay its internal and external branches
• prolonged, intense tumor blush
• resectability depends on angle between ICA and ECA
• patients often left with hoarseness due to proximity of vagus nerve
• preoperative embolization may be considered

3. Meningioma:

• highly vascular extra-axial neoplasm 
• core is supplied by branches of the ECA while periphery is supplied by the ICA
• "spoke wheel" appearance on angiogram
• resection is usually curative
• large tumors may be embolized prior to resection

REFERENCES

Pribram HFW. Selective catheterization of the external carotid artery. Radiology 1966;87:315-20.

Roberson GH, Price AC, Davis JM, et al. Therapeutic embolization of juvenile angiofibroma. AJR Am J Roentgenol 1979;133:657-63.

Wieneke JA, Smith A. Paraganglioma: carotid body tumor. Head Neck Pathol 2009;3(4)303-6.

Wilson G, Weidner W, Hanafee W. The demonstration and diagnosis of meningiomas by selective catheter angiography. AJR Am J Roentgenol 1965;95(4):868-73.

Mycetoma Formation in Fungal Sinusitis

A mycetoma (fungal ball) is an uncommon sequela of fungal sinusitis and is thought to be secondary to deficient mucociliary clearance of a fungal organism which incites an inflammatory response. The fungal ball usually appears as a mass within a sinus (usually the maxillary sinus) and is typically unilateral. Bone window CT will show a mass within the sinus with punctate calcifications. A fungal ball is typically of low signal intensity on T1W MR due to low water content. On T2WI the mycetoma will be hypointense relative to the hyperintense inflamed sinus mucosa.


REFERENCES
Aribandi M, McCoy VA, Bazan C. Imaging features of invasive and noninvasive fungal sinusitis: a review. Radiographics 2007;27:1283-96.

Internal Derangement of the Temporomandibular Joint

Internal Derangement of the Temporomandibular Joint (TMJ), more commonly known as dislocation of the TMJ, occurs due to an abnormal positional and functional relationship between the articular disc and the articulating surface. The images above are from a patient with anterior dislocations of the bilateral TMJs.

While this abnormality can usually be detected on plain films or bone NECT, MRI is the best modality to evaluate the TMJ especially in cases of recurrent derangement. On MRI, the low signal intensity articular disc will be displaced relative to the mandibular condyle. T1WI can show specific disc abnormalities including perforation, fibrosis or adhesions. The presence of a joint effusion can be detected as high signal on T2WI. The presence of synovitis can be detected as enhancement of the disc on T1WI after administration of contrast.


REFERENCES
Sommer OJ, Aigner F, Rudisch A, et al. Cross-sectional and functional imaging of the temporomandibular joint: radiology, pathology, and basic biomechanics of the jaw. Radiographics 2003;23:e14.
Tomas X, Pomes J, Berenguer J, et al. MR imaging of temporomandibular joint dysfunction: a pictorial review. Radiographics 2006;26:765-81.

Normal Variants in the Pediatric Cervical Spine

Interpreting cervical spine x-rays in the pediatric population can be a challenge due to normal anatomic variants. At age 8-10 a child's cervical spine reaches adult proportions. Normal variants to be considered in the younger populations include:

1. The atlantodens interval (ADI) may be up to 5mm in the pediatric patient whereas the upper limit of normal is 3mm in an adult.
2. Pseudo-Jefferson fracture: up to 6mm displacement of the lateral masses of atlas on the axis on the open mouth view is normal for children up to age 7.
3. Pseudo-subluxation of C2 on C3 (and to a lesser extent C3 on C4): normal mobility of upper cervical spine (due to ligamentous laxity) can cause up to a 4mm anterior displacement of C2 on C3. The Swischuk line - a line drawn through the posterior arch of C2 should be within 2mm of the spinolaminar line drawn at C1-C3 - can be used to determine whether this finding is normal or due to possible hangman's fracture. A discrepancy of > 2mm can indicate a fracture.
4. Anterior "wedging" of up to 3mm is a normal finding. 
5. Ossification centers and unfused apophyses may mimic fractures.
6. Absence of cervical spine lordosis may be seen up to age 16.

REFERENCES
Curtin P and McElwain J. Assessment of the "nearly normal" cervical spine radiograph: C2-C3 pseudosubluxation in an adult with whiplash injury. Emerg Med J 2005;22:907-8.
Lustrin ES, Karakas SP, Ortiz AO, et al. Pediatric cervical spine: normal anatomy, variants, and trauma. Radiographics 2003;23:539-60.

Hereditary Syndromes Associated with Craniosynostoses

Dolichocephaly is a craniosynostosis involving premature closure of the sagittal suture resulting in an elongated head shape as shown above. The craniosynostoses were previously discussed here: craniosynostoses.

Hereditary syndromes that are associated with craniosynostoses are:
Crouzon syndrome: premature synostosis, maxillary hypoplasia, shallow orbits
Apert's syndrome: Coronal synostosis, midfacial hypoplasia, bilateral syndactyly, symphalangism (ankylosis of interphalangeal joints)
Pfeiffer syndrome: premature synostosis, broad thumbs and great toes, mild syndactyly
Carpenter syndrome: premature synostosis, severe developmental delay, brachydactyly, syndactyly, thumb duplication.

Acquired conditions that can result in premature synostosis include Rickets, hypophosphatasia, and mucopolysaccharidoses.

REFERENCES
Glass RBJ, Fernbach SK, Norton KI, et al. Radiographics 2004;24:507-22.

Phthisis Bulbi

Phthisis bulbi refers to an atrophic, disorganized globe with calcifications. It is an end-stage ocular condition that can be a sequela of ocular inflammation, trauma, radiation, infection, and retinal detachment. The effected eye is non-functioning. 

The above images demonstrate a shrunken, calcified left globe in a patient with confirmed phthisis bulbi. The patient has had scleral banding on the right.


REFERENCES

LeBedis CA and Sakai O. Nontraumatic orbital conditions: diagnosis with CT and MR imaging in the emergent setting. Radiographics. 2008 October;28:1741-53.
Mafee MF. The eye. In: Som PM, Curtis HD, eds. Head and neck imaging. 4th ed. St. Louis, MO: Mosby, 2003; 441-527.