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

Ulnar Dimelia

Ulnar dimelia is a rare congenital disorder characterized by duplication of the ulna, absence of the radius, and polydactyly. Patients can also have arterial anomalies, such as absence of the radial artery, duplication of the ulnar artery, and abnormal arterial arches in the hand. Nerve anomalies may also be present and include shortening of the radial nerve and duplication of ulnar nerve (with or without connections to the median nerve)

Radiopaedia has some great images of type I ulnar dimelia

Distinguishing features of the two types of ulnar dimelia
Feature	Type I	Type II
Index finger	1	2
Lunate	1	2
Trapezoid	1	2

References

• Afshar A. Ulnar dimelia without duplicated arterial anatomy. J Bone Joint Surg Br. 2010 Feb;92(2):293-6. doi: 10.1302/0301-620X.92B2.23057.
• Tomaszewski R, Bulandra A. Ulnar dimelia-diagnosis and management of a rare congenital anomaly of the upper limb. J Orthop. 2015 Feb 18;12(Suppl 1):S121-4.

Chondroblastoma

General

• Terminology: “giant cell variant” (1927) → epiphyseal chondromatous giant cell tumor → calcifying giant cell tumor → chondroblastoma
• 1% to 2% of all primary bone tumors
• 9% of all benign bone tumors
• Mean age of 15-18 years
• M >>F
• Mean duration of symptoms 8.7 months
• Trivia: Most common benign neoplasm of the patella

Imaging Features

• Epiphysis/apophysis +/- metaphyseal/diaphyseal involvement
• Metaphyseal/diaphyseal occurrence without epiphyseal/apophyseal involvement exceptionally rare
• Proximal tibia >> proximal femur > distal femur > proximal humerus
• Well-defined, sclerotic margins on radiographs
• Can involve the cortex, resulting in expansion, thinning, or disruption.
• Stippled matrix calcification seen in minority of cases
• Periosteal reaction seen in majority of cases
• Extensive peri-lesional edema on MRI is common
• Homogeneously hypointense on T1
• Variable on T2: can be diffusely hypointense, or have small cystic areas of increased T2 signal or fluid-fluid levels
• Heterogeneous and moderate enhancement in solid portions. Less commonly, homogeneous and marked enhancement

Differential Diagnosis

• Clear cell chondrosarcoma: Typically older patients
• Osteoid osteoma: Usually has intense perilesional sclerosis and edema.
• Langerhans cell histiocytosis:
• Chondromyxoid fibroma: Rare lesion. Usually in the metaphyses of the long tubular bones, especially the tibia and femur near the knee joint. May cross open growth plates into epiphyses or apophyses.

Management/Prognosis

• Curettage or resection
• RFA (small lesions, small series, not common)
• Local recurrence rate: 5.0% after curettage
• Local recurrence rate: 0% after resection
• Recurrence most frequent in the proximal humerus
• Malignant transformation and benign pulmonary metastases extremely rare

References

• Christie-Large M, Evans N, Davies AM, James SL. Radiofrequency ablation of chondroblastoma: procedure technique, clinical and MR imaging follow up of four cases. Skeletal Radiol. 2008 Nov;37(11):1011-7.
• Kaim AH, Hügli R, Bonél HM, Jundt G. Chondroblastoma and clear cell chondrosarcoma: radiological and MRI characteristics with histopathological correlation. Skeletal Radiol. 2002 Feb;31(2):88-95.
• Singh J, James SL, Kroon HM, Woertler K, Anderson SE, Jundt G, Davies AM. Tumour and tumour-like lesions of the patella--a multicentre experience. Eur Radiol. 2009 Mar;19(3):701-12.
• Xu H, Nugent D, Monforte HL, Binitie OT, Ding Y, Letson GD, Cheong D4, Niu X. Chondroblastoma of bone in the extremities: a multicenter retrospective study. J Bone Joint Surg Am. 2015 Jun 3;97(11):925-31.

Subperiosteal hemorrhage in neurofibromatosis type 1

Neurofibromatosis type 1 (NF-1), in addition to a neuroectodermal disorder, is accompanied by mesodermal dysplasia that is accompanied by skeletal changes. The typical osseous findings include bowing of the legs, increase in length of long bones, pseudarthrosis, subperiosteal cyst formation, local bony erosions from adjacent lesions, and intramedullary neurofibromas. Except for the last two, which are due to direct involvement by neurofibromas, the remainder are due to dysplastic changes in bones.

A lesser known osseous presentation in bone is the propensity for subperiosteal hemorrhage and hematoma formation. The cause is unknown, but may be related to:

• Vascular abnormalities: For example, diffuse flat hemangiomas or plexiform dilated veins, which have been described in patients with hypertrophy of the extremities
• Dysplastic periosteum: The thinking is that mesodermal dysplasia manifests as an abnormally loose periosteum with poor callus response. This would predispose the patient to the formation and propagation of large subperiosteal hematomas.
• Direct involvement by neurofibromas: Subperiosteal infiltration by neurofibromatous tissues may loosen the periosteum and allow for massive hemorrhage following minor trauma.

References

• Herrera-Soto JA, Crawford AH, Loveless EA. Ossifying subperiosteal hematoma associated with neurofibromatosis type 1. Diagnostic hesitation: a case report and literature review. J Pediatr Orthop B. 2005 Jan;14(1):51-4.
• Steenbrugge F, Verstraete K, Poffyn B, Uyttendaele D, Verdonk R. Recurrent massive subperiosteal hematoma in a patient with neurofibromatosis. Eur Radiol. 2001;11(3):480-3.
• Yaghmai I, Tafazoli M. Massive subperiosteal hemorrhage in neurofibromatosis. Radiology. 1977 Feb;122(2):439-41.

ILAR Classification of Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is an umbrella term for a group of abnormalities characterized by chronic articular inflammation and association with HLA alleles. The International League Against Rheumatism (ILAR) has classified JIA into seven subtypes, including an unclassifiable group. These include:

• Systemic arthritis: Arthritis in one or more joints with or preceded by fever of at least 2 weeks' duration documented to be daily for at least 3 days, and accompanied by one or more of: evanescent erythematous rash, lymphadenopathy, hepatomegalyor splenomegaly, or both, serositis
• Oligoarthritis: Arthritis in 4 or fewer joints in the first 6 months. Subtypes include persistent (no more than 4 joints throughout the course of the disease) and extended (more than 4 joints after the first 6 months).
• Polyarthritis, RF negative: Arthritis affecting 5 or more joints in the first 6 months of disease. RF is negative
• Polyarthritis, RF positive: Arthritis affecting 5 or more joints in the first 6 months of disease. Two or more tests for RF, conducted at least 3 months apart during the first 6 months, are positive. Considered the pediatric version of adult rheumatoid arthritis.
• Psoriatic: Arthritis plus psoriasis OR Arthritis plus at least two of the following: dactylitis, nail pitting or onycholysis, psoriasis in a first-degree relative.
• Enthesis-related: Arthritis plus enthesitis OR Arthritis or enthesitis, plus at least two of the following: presence of or a history of sacroiliac joint tenderness and/or inflammatory lumbosacral pain‡, presence of HLA-B27 antigen, onset of arthritis in a male over 6 years of age, acute (symptomatic) anterior uveitis, history of AS, ERA, sacroiliitis with IBD, reactive arthritis, or acute anterior uveitis in a first-degree relative
• Unclassified: Arthritis that fulfills criteria in none of the above categories, or fulfills criteria in two or more of the above categories

References

Petty RE, Southwood TR, Baum J, Bhettay E, Glass DN, Manners P, Maldonado-Cocco J, Suarez-Almazor M, Orozco-Alcala J, Prieur AM. Revision of the proposed classification criteria for juvenile idiopathic arthritis: Durban, 1997. J Rheumatol. 1998 Oct;25(10):1991-4.

Osteochondritis Dissecans Revisited

Coronal and sagittal T1 and T2WI demonstrate curvilinear low signal intensity in the medial femoral condyle on T1WI with high signal on the corresponding T2WI. Findings are consistent with osteochondritis dissecans previously discussed here.

Causes of UPJ Obstruction

Congenital

• Abnormality of collagen muscle causing stenosis at the UPJ
• High ureteral insertion
• Aberrant crossing renal vessels: arteries/vein at the renal hilum crossing anterior or posterior to the ureter can cause obstruction
• Failure of recanalization of the ureter (considered less likely)
• Presence of valves/kinks (considered less likely)

Acquired

• Vesicoureteral reflux
• Stricture or stenosis secondary to trauma, recurrent infection, instrumentation, calculi
• Neoplasm: benign (polyp) or malignant (transitional cell, squamous cell)

REFERENCES
Lawler LP, Jarret TW, Corl FM, Fishman EK. Adult ureteropelvic junction obstruction: insights with three-dimensional multi-detector row CT. Radiographics 2005;25:121-34.

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. 

The Flat Cava Sign

Flattening of the IVC is most commonly described in patients with abdominal trauma leading to hypovolemia and hypoperfusion of the bowel ("shock bowel."). The IVC is considered "flattened" if its AP diameter is less than 9 mm at the level of the renal veins. Associated imaging findings of the "hypovolemia complex" include decreased caliber of the abdominal aorta, increased enhancement of the bowel mucosa, and prolonged intense enhancement of the adrenal glands.

In pediatric patients the constellation of findings seen with post traumatic shock is called the "hypoperfusion complex." Imaging findings include fluid-filled, dilated bowel; increased enhanced of the bowel wall, mesentery, kidneys, pancreas, adrenal glands, aorta, and IVC; decreased caliber of the aorta and IVC. Presence of these findings indicates a poor prognosis.


REFERENCES
Eisenstat RE, Whitford AC, Lane MJ, et al. The "Flat Cava" sign revisited: What is its significance in patients without trauma? AJR Am J Roentgenol 2002;178(1):21-5.
O'Hara SM, Donnelly LF. Intense contrast enhancement of the adrenal glands: another abdominal CT finding  associated with hypoperfusion complex in children. AJR Am J Roentgenol 1999;173(4):995-7.

Enlarged Parietal Foramina

Enlarged parietal foramina are considered a benign normal variant in calvarial ossification. They are associated with anomalies of cerebral venous development, variations in occipital cortical infolding, scalp defects, and cleft palate. Although sometimes palpable, these defects are usually discovered incidentally. For patients with prominent foramina, cerebral vascular imaging may be considered for work up of aforementioned anomalies.

REFERENCES

Fink AM and Maixner W. Enlarged parietal foramina: MR imaging features in the fetus and neonate. AJNR 2006;27:1379-81.

Reddy AT, Hedlund GL, Percy AK. Enlarged parietal foramina: association with cerebral venous and cortical anomalies. Neurology 2000;54(5):1175-8.

Dyke Davidoff Masson Syndrome

Dyke Davidoff Masson Syndrome (DDMS) is a neurodegenerative disorder likely due to cerebral injury in utero or early in life. The main finding is cerebral hemiatrophy. Associated findings include ipsilateral compensatory calvarial thickening, enlarged frontal sinus, elevation of the petrous ridge and sphenoid wing.

The above images are from a young boy who presented with a history of seizures. There is asymmetric atrophy of the left cerebral hemisphere. Bone window examination demonstrates enlargement of the left frontal sinus.


REFERENCES
Grossman RI, Yousem DM. Neuroradiology, the requisites. Mosby Inc. (2003)

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.

Trapped Periosteum in Physeal Injuries

Physeal injuries are common in the pediatric population and are usually classified by the Salter Harris system. One of the complications of physeal fractures is trapped periosteum. This can render a fracture as irreducible which may result in premature physeal closure. Trapped periosteum is important to recognize on imaging because it requires open reduction to prevent growth disturbances. 

On radiographs and CT with mulitplanar reconstruction, peristent physeal widening > 3mm after closed reduction is suggestive of trapped periosteum. The MRI findings of trapped periosteum have not been adequately described in the literature. A few reports seem to concur that on proton density weighted fat-suppressed images trapped periosteum appears as a low signal band insinuating at the physis. 


REFERENCES
Barmada A, Gaynor T, Mubarak SJ. Premature physeal closure following distal tibia physeal fractures: a new radiographic predictor. J Pediatr Orthop 2003;23:733-9.
Whan A, Breidahl W, Janes G. MRI of trapped periosteum in a proximal tibial physeal injury of a pediatric patient. AJR Am J Roentgenol 2003;181:1397-9.

Segmental Testicular Infarction

The presentation of an acute scrotum in the emergency setting typically leads to a work up for testicular torsion with ultrasound imaging. Accurate diagnosis of acute testicular torsion is important because the risk of global testicular infarction increases with time from onset of symptoms. 

Segmental testicular infarction is a rarer entity that is not well described in the literature. Ultrasound will demonstrate wedge shaped, hypoechoic regions in the testes with absence of vascular flow. The differential diagnosis for this finding is:

• polycythemia vera
• intimal hyperplasia of the spermatic artery
• sickle cell anemia
• vasculitis
• systemic lupus erythematosus
• polyarteritis nodosa
• venous thromboses (in hypercoagulable states)
• severe epididymo-orchitis that is unresponsive to treatment
• trauma

Differentiation between these entities and testicular torsion is important because treatment of the underlying condition (i.e. with steroids for polyarteritis nodosa) can prevent an unnecessary orchidectomy.


REFERENCES
Fernandez-Perez GC, Tardaguila FM, Velasco M, et al. Radiologic findings of segmental testicular infarction. AJR Am J Roentgenol 2005;1587-93.
Sriprasad S, Kooiman GG, Muir GH, et al. Acute segmental testicular infarction: differentiation from tumor using high frequency colour Doppler ultrasound. BJR 2001;74:965-7.

The Molar Tooth Sign - Joubert Syndrome

Joubert syndrome is an autosomal recessive disorder characterized by cerebellar vermian hypoplasia with a midline cleft and lack of decussation of the superior cerebellar peduncles, the latter causing an enlargement of the peduncles. Other decussation defects of the central pontine and corticospinal tracts as well as dysplasia of the olivary nuclei may also be present. Associated renal, retinal, and hepatic abnormalities are often seen. 

The molar tooth sign refers to the characteristic appearance of the midbrain seen on axial imaging (CT or MR) in patients with Joubert syndrome. Thickened superior cerebellar peduncles surrounding an elongated fourth ventricle give this appearance. A vermian cleft may also be recognized.


REFERENCES
McGraw P. The molar tooth sign. Radiology 2003;29:671-2.

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.

The Spectrum of Esophageal Atresias

Esophageal atresia is a congenital anomaly related to incomplete formation of the esophagus with or without the presence of a tracheoesophageal (TE) fistula. While the exact cause is unknown, it is felt to be related to incomplete separation of the primitive foregut into the trachea and the esophagus. One accepted classification of esophageal atresia and TE fistulas is as follows:

A. Atresia without TE fistula
B. Atresia with proximal TE fistula
C. Atresia with distal TE fistula (most common)
D. Atresia with proximal and distal TE fistula
E. TE fistula without atresia

Esophageal atresia is usually suspected in the setting of polyhydramnios, excessive salivation, choking/cyanosis during feeding, and inability to pass a nasogastric/feeding tube to the stomach. Anteroposterior and lateral radiographs will reveal a blind-ending, air-filled proximal esophagus. Radiographs of the abdomen should also be performed to evaluate for air in the GI tract, the presence of which raises suspicion for a distal TE fistula. Fluoroscopy may be used to confirm findings in which case water soluble contrast is preferred.

The above images are from a newborn with a history of difficulty feeding. The initial radiograph reveals a dilated upper esophagus without air seen in the GI tract. A nasogastric tube was placed which coiled in the proximal esophageal stump. Via a percutaneous gastrostomy tube, contrast was introduced into the stomach which refluxed into a distal esophageal remnant without evidence for fistulous connection. Type A esophageal atresia was diagnosed.


REFERENCES

Berrocal T, Torres I, Gutierrez J, et al. Congenital anomalies of the upper gastrointestinal tract. Radiographics. 1999;19:855-72.

Bisphosphonate Therapy in Children

Pediatric patients with cerebral palsy and osteogenesis imperfecta can be treated with bisphosphonates for low mineral density. In addition, third-generation bisphosphonates, such as zoledronic acid and minodronic acid have been shown to have antitumor effects in various cancers such as osteosarcoma and Ewing sarcoma. The use in children is classified as "off-label."

Radiographs reveal dense stripes parallel to the growth plate, an appearance that has been termed zebra lines. Dense metaphyseal bands tend to occur in patients treated continuously, while thin bands tend to occur in patients treated intermittently. In addition, patients treated intermittently tend to have increased bone density, increased growth, and decreased number of fractures.

The sclerotic bands correspond to decreased osteoclastic activity during drug administration, and the spaces between the bands corresponds to resumption of osteoclastic activity and linear growth of bone between treatments. With time (3-4 years), these dense bands become less distinct and eventually disappear into the diaphysis.

While similar to Harris growth arrest lines, zebra lines tend to be more widespread in epiphyseal, apophyseal, and metaphyseal regions of all growing bones. Growth arrest lines, on the other hand, are seen in the metaphyses of rapidly growing bones (e.g., distal femur, proximal and distal tibia, and proximal humerus) and may be limited to a single bone (e.g., following a major fracture).

References

• Al Muderis M, Azzopardi T, Cundy P. Zebra lines of pamidronate therapy in children. J Bone Joint Surg Am. 2007 Jul;89(7):1511-6.
• Grissom LE, Harcke HT. Radiographic features of bisphosphonate therapy in pediatric patients. Pediatr Radiol. 2003 Apr;33(4):226-9.

F18-FDG PET in Neuroendocrine Tumors

Somatostatin receptor scintigraphy (e.g., octreoscan) is more sensitive than both ¹²³I-MIBG scintigraphy and ¹⁸F-FDG PET for neuroendocrine tumors. However, ¹⁸F-FDG PET is more sensitive for detection of aggressive tumors, with a sensitivity of around 90%, compared to ~70% and ~45% for somatostatin receptor and ¹²³I-MIBG scintigraphy for tumors with proliferation index above 15%.

In these aggressive tumors, somatostatin receptor and ¹²³I-MIBG scintigraphy can underestimate the extent of disease dissemination and lead to suboptimal treatment for these patients (aggressive disease is treated with systemic chemotherapy, while less aggressive disease is treated with somatostatin analogs or α-interferon).

In the example above, FDG-PET shows uptake in several areas not seen on octreoscan. One example is an enlarged retroperitoneal lymph node that is not hot on octreoscan, but light s up on FDG-PET (black arrows).

References

Binderup T, Knigge U, Loft A, Mortensen J, Pfeifer A, Federspiel B, Hansen CP, Højgaard L, Kjaer A. Functional imaging of neuroendocrine tumors: a head-to-head comparison of somatostatin receptor scintigraphy, 123I-MIBG scintigraphy, and 18F-FDG PET. J Nucl Med. 2010 May;51(5):704-12.