Spine bone tumors in children. A pictorial review

Spine bone tumors in children. A pictorial review Poster No.: C-1921 Congress: ECR 2015 Type: Educational Exhibit Authors: E. García Esparza, S. I. Sirvent Cerdá, M. Á. López Pino, I. Solís Muñiz, G. Albi Rodríguez; Madrid/ES Keywords: Cancer, Education, MR, CT, Pediatric, Oncology, Bones, Neoplasia DOI: 10.1594/ecr2015/C-1921 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 20

Learning objectives To review bone tumors found in the spine in the pediatric population with highlight in imaging features that can help the radiologist characterize the lesions. Background A variety of bone tumors can be found in the spine in children. They are not very frequent in children and the differential diagnosis can be difficult. Findings and procedure details Plain film is essential in the imaging study of bone tumors but when they sit in the spine it is not that useful. The complex anatomy of the spine makes it difficult to assess important imaging features such as calcified matrix, zone of transition or precise anatomic location. This is why CT is usually required in these tumors. MRI is also mandatory to assess extension into the paraspinal and epidural spaces. We present a pictorial review of the various bone tumors of the spine found in children, some of them fairly common, such as osteoid osteoma, leukemia, metastases or Langerhans cell histiocytosis and some not as common as aneurysmal bone cyst, giant cell tumor, Ewing sarcoma and osteosarcoma. We discuss imaging features that are typical for the various entities using both CT and MRI. Benign tumors 1.- Bone island It is the more common lesion in the spine. It can be seen in plain film and CT as a dense lesion in the medullary bone, with or without attachment to the bone cortex. It Page 2 of 20

represents lamellar compact bone. The typical appearance is "thorny" or "brush border" that represent the normal trabeculae radiating from the lesion. It is frequently found on images done for other medical reasons and does not require follow-up. Fig. 1 on page 5 2.- Langerhans cell histiocytosis 9% of the Langherhans cell histiocytosis are located in the spine, most frequently in the thoracic spine. They are lytic lesions with soft tissue component, they affect the body of the vertebra and they are usually detected in the lateral plain film as loss of height of the vertebral body that eventually leads to the complete collapse of the vertebral body: vertebra plana. CT shows a lytic lesion with indistinct margins. The soft tissue component can be epidural or paraspinal and can be better depicted in MRI as a hyperintense lesion in T1WI, hyperintense in T2 and with heterogenous enhancement after contrast administration. The intervertebral discs are spared. Fig. 2 on page 6 3.- Osteoid osteoma Osteoid osteoma is a benign tumor that occurs more frequently in long bones. Approximately 10% of them sit in the spine, almost all in the posterior elements sparing the vertebral body. CT is the recommended image for the diagnosis. The classical findings in CT are a lucent nidus with central calcification that is the tumor itself, surrounded by a zone of reactive sclerosis. The findings in MR are not specific and very often only bone marrow edema is visible as an area of hyperintensitity in T2WI that usually enhances after contrast administration. The nidus itself can be missed in MRI. It is important to think about osteoma osteoide as MRI is very often performed before CT in the investigation of a child with back pain and only bone marrow in a lamina is found. CT-guided radiofrequency ablation is the treatment of choice in most cases. Fig. 3 on page 7 4.- Osteoblastoma It is an osteoid forming tumor similar to osteoma osteoide that differs from it by the larger size of the osteoblastoma. 40% of osteoblastomas occur in the spine. They usually arise in the posterior elements but can extend into the vertebral body. They are lytic lesions, larger than 1.5 cm, with a well circumscribed margin in CT. They usually show less surrounding sclerosis than osteoma osteoid. They have extensive peritumoral edema Page 3 of 20

("flare phenomenon"), better depicted in MRI, that can mislead the radiologist, mimicking more aggressive lesions. Fig. 4 on page 8 5.- Aneurysmal bone cyst It is an expansile neoplasm composed of thin-walled, blood-filled cavities. They occur in the neural arch and may extend to vertebral body. Cortical thinning and destruction is common. The best imaging clue in MRI is to detect multiple cyst with fluid-fluid level in them. These are not pathognomonic though, and malignant tumors, such as telangiectatic osteosarcoma can feature fluid-fluid levels in them. Fig. 5 on page 9 Malignant tumors 7.- Osteosarcoma It is a malignant tumor that produces inmature bone. It usually arises in the posterior elements Fig. 6 on page 10. It is an aggressive looking lesion, permeative, with a wide zone of transition, that breaks the cortical and with soft tissue mass, that very often invades the spinal canal. Mineralized osteoid bone matrix is usually found in CT scan, but some can be purely lytic in appearance Fig. 7 on page 11. In MRI it looks like other sarcomas: hypointense in T1WI, hyperintense in T2WI, enhances after gadolinium and invades adjacent estructures such as paravertebral muscles and spinal canal. 8.- Ewing sarcoma It is a malignant round cell sarcoma of the bone. It originates more frequently from the vertebral body than from the posterior elements. It is a lytic, permeative lesion, with wide zone of transition, that invades the adjacent estructures with soft tissue mass Fig. 8 on page 12. In 5% of cases it can be sclerotic Fig. 9 on page 13. CT scan can depict very nicely the permeative moth eaten pattern of bone destruction. Even though it can be sclerotic, no calcification is seen within the soft tissue mass. MRI is better to asses infiltration of intraespinal or paraspinal structures. The main differential is with other sarcomas, such as osteosarcoma, undifferentiated sarcoma Fig. 10 on page 14, metastases, osteomyelitis and Langerhans cell histiocytosis. Page 4 of 20

9.- Metastases The most frequent source of bone metastases in children is round cell sarcomas, such as neuroblastoma, rhabdomyosarcoma Fig. 11 on page 15 or Ewing sarcoma and hematologic malignancies (lymphoma and leukemia) Fig. 12 on page 16. They are usually lytic, permeative lesions, but sometimes they are not detectable in radiographs or CT scan until there is enough percentage of bone destruction. They can range from small round lesions to affect the whole vertebra, with compression fractures and epidural mass at different levels. 10.- Sacrococcygeal germ cell tumor As in other locations there are benign and malignant varieties, from classic teratoma, containing fat, hair, teeth, solid and cystic components to completely solid masses. Only 17% are malignant. They are usually diagnosed in prenatal ultrasound or soon after birth, but the diagnosis can be delayed, especially in type IV (internal) masses. The origin is the coccyx and can grow in any direction. Classification: Type I (47%) primarily external Type II (34%) Dumbbell shape (equal size of intraabdominal and external components) Fig. 13 on page 17 Type III (9%) larger intraabdominal/ intrapelvic component Type IV (10%) no external component visible. Images for this section: Page 5 of 20

Fig. 1: Bone island. 8 year old girl with acute lymphoblastic leukemia and bone marrow transplantation. Abdominal CT was performed because of acute abdominal pain. A bone island is seen in the body of the 4th lumbar vertebra as a dense, well defined lesion (a, b). Prior lumbar X-rays were reviewed and the lesion was also visible (c). Page 6 of 20

Fig. 2: Langerhans cell histiocitosis. Back pain in a three year old girl. Lateral spine plain film (a): compression fracture in the body of L3. CT (b, c): lytic lesion, with indistinct margins affecting the body of L3, that is almost completely collapsed, and the right pedicle. MRI: vertebral body collapse. Intermediate signal lesion in T1 WI (e), hyperintense in T2WI (f) that enhances heterogeneously (g), small paravertebral and epidural soft tissue mass. Langerhans cell histiocytosis was highly suspected, but the biopsy should be performed if posible (d). Three months later (h): vertebra plana Page 7 of 20

Fig. 3: Osteoid osteoma. 13 year old boy with a 2 years history of sacroiliac related pain. MR was performed to rule out sacroileitis and a subtle lesion was found in the right lamina of L5, almost indetectable in T1WI (a) but slight hyperintensity in T2WI (b) and enhancement (c) were noted (arrows). CT suspecting osteoma osteoide (d, e): Small lytic lesion in the right lamina os L5 (arrow) with calcification surrounded by sclerotic bone. Radiofrequency ablation guided by CT (f, g) was performed. Page 8 of 20

Fig. 4: Osteoblastoma. 14 year old girl. 5 months history of cervical pain that radiates to the left arm; partial response to nonsteroidal anti-inflammatory drugs. TC (a, b, c): Lytic well defined lesion in the left lamina of C4, that breaks the internal cortex, with mild calcification consistent with osteoid formation (arrow). MRI: he lesion is intermediate signal in T1WI (d), very hyperintense in STIR (e) and enhences intensely with gadolinium. The hyperintensity and enhancemente of the soft tissues is known as "flare phenomenon", it is due to edema and can mimic more aggressive lesions. Page 9 of 20

Fig. 5: Aneurysmal bone cyst. 13 year old boy with a history of several months of back pain. The AP spine plain film (a) shows a subtle thinning of the cortex of the left pedicle of L5 (arrow). CT: lytic lesion with marginated but not sclerotic margins in the lamina, pedicle and part of the body of L5. MRI: The lesion is composed by multiple cysts, many of them with fluid-fluid levels in T2WI (c) and with enhancement of the walls of the cysts (d). After several embolizations and partial relapses the lesion has grown bigger (e, f) Aneurysmal bone cyst has a hage recurrent rate. Page 10 of 20

Fig. 6: Osteosarcoma. 9 year old girl with a history of lumbar pain and right sciatica. Lateral plain film of the lumbar spine (a): lytic lesion in the posterior elements of L5 (arrow). CT (b, c): Lytic lesion in the right lamina, with cortical rupture and osteoid calcification that invades the lumbar canal. MRI: the lesion is hypointense in T1WI (e), Hyperintense in T2WI fat sat, and enhances after gadolinium administration. It invades the lumbar canal displacing the sac, extends into the vertebral body and the paravertebral muscles. The differential diagnosis was between aggressive osteoblastoma and osteosarcoma. Page 11 of 20

Fig. 7: Osteosarcoma. 11 year old girl with a hisory of three months of back pain. Plain films (a, b): extensive lytic lesion in the posterior elements of L5 (arrow) The pedicles are not visible in the AP projection (b). CT (c, d, e, f): Expansile, lytic lesion affecting espinosa, both lamina, pediculae an most of the vertebral body, with no osteoid formation to be seen. MRI: the lesion is hypointense in T1WI (g), intermediate in T2WI fat sat and enhances intensely after gadolinium administration (i, j) Page 12 of 20

Fig. 8: Ewing sarcoma. 17 years old boy. Pain in the back and the left leg lasting one month. He is unable to walk on his toes. CT (a): Subtle sclerosis of L5, that affects vertebral body and posterior elements, with indistinct margin of the cortex (arrows), but no clear periosteal reaction. MRI: Signal alteration and heterogenicity of the whole vertebra, hypointense in T1WI (b), hyperintense in T2WI (c), with heterogeneous enhancement (d, e). Epidural mass (asterisk) and infiltration of the paraespinal muscles (open arrow) is also seen. Page 13 of 20

Fig. 9: Ewing sarcoma. 8 year old boy. 3 months of lumbar pain and one month of right leg pain. Lateral spine plain film (a): sclerosis and slight loss of height in the body of L2. CT (b, c) aggressive sclerotic/ lytic lesion in the body and both pedicles of L2, with spiculated periosteal reacction and pathological compression fracture. MRI: Most of the vertebra is involved by the tumor and there is a big soft tissue mass infiltrating both psoas, paravertebral muscles and lumbar canal, hypointense in T1WI (f), hyperintense in T2WI (d, g) and with very scarce enhancement after gadolinium administration (e, h) Page 14 of 20

Fig. 10: Undifferentiated sarcoma. 9 year old girl with a history of pain in the back of the right thigh and lack of plantar flexion of the right foot. MRI: solid sacral mass, hypointense in T1 WI (a), Hyperintense in T2WI fat sat (b, c) that enhances intensely (d). It had a big soft tissue mass that extended to the right sacral foramina (asterisk), paravertebral muscles and with a large intrapelvic component. CT (e): permeative lytic lesion with indistinct margins that was biopsied (f). Ewing sarcoma was suspected due to these images, but the pathologic diagnosis was undifferentiated sarcoma. Page 15 of 20

Fig. 11: Metastases of rhabdomyosarcoma. 11 year old with a known history of neurofibromatoses type 1. Arrives at the ER with perianal pain and constipation. MRI: Big perianal mass, Hypointense in T1WI (a), hyperintense in T2WI and enhancing after gadolinium administration (c). A bone lesion is noted in the sacrum (arrows) consistent with metastases. The lesion is not visible in the CT (d) probably because not enough bone is destroyed. Page 16 of 20

Fig. 12: Leukemia. 9 year old boy with one month history of dorso-lumbar pain, anorexia and loss of weight. Lateral spine plain film (a): Several vertebral spine compression fractures (arrows). MRI: The collapsed vertebrae (arrows) and some others (asterisks) have very low signal in T1WI (b), and are hyperintense in T2WI (c). TC: very subtle permetive lysis of several vertebral bodies (d) and pelvic wing (arrow in e), with periosteal reaction. The sacrum was biopsied (f) Page 17 of 20

Fig. 13: Malignant germ cell tumor. 18 months old boy with a palpable mass in the coccygeal region. Plain film (a): large soft tissue mass, no calcification. The coccix is barely seen (arrow) due to diminished density. US (b, c): large soft tissue mass, homegeneous ecogenicity except for many large vessels, better seen in the color doppler image. MRI (d, e, f, g): the lesion is hypointense in T1WI (d), intermediate in T2WI (e) and with heterogeneous enhancement (f). It shows marked restriction in the diffussion image (g) Page 18 of 20

Conclusion Spine bone tumors in children are better assessed with both CT and MRI. Age, tumor location in the vertebra, imaging features and clinical findings are clue in the differential diagnosis. Personal information References Ross J. S et al. Diagnostic Imaging. Spine. 2 nd ed. Salt Lake City. Amirsys. 2010 1 Demaerel P, Van Gool S. Paediatric neuroradiological aspects of Langerhans cell histiocytosis. Neuroradiology. 2008;50(1):85-92 1 Martel J, Bueno A, Nieto-Morales ML, Ortiz EJ. Osteoid osteoma of the spine: CT-guided monopolar radiofrequency ablation. Eur J Radiol. 2009;71(3):564-9 1 Zbojniewicz AM, Hartel J, Nguyen T, Wilks K, Mace A, Hogg JP. Neoplastic disease of the vertebral column: radiologic-pathologic correlation. Curr Probl Diagn Radiol. 2010;39(2):74-90 1 Ropper AE,Cahill KS,Hanna JW, McCarthy EF,Gokaslan ZL,Chi JH. Primary vertebral tumors: a review of epidemiologic, histological, and imaging findings, Part I: benign tumors. Neurosurgery.2011;69(6):1171-80 Page 19 of 20

1 Ropper AE, Cahill KS, Hanna JW, McCarthy EF, Gokaslan ZL, Chi JH. Primary vertebral tumors: a review of epidemiologic, histological and imaging findings, part II: locally aggressive and malignant tumors. Neurosurgery. 2012;70(1):211-9 1 Harrop JS, Schmidt MH, Boriani S, Shaffrey CI. Aggressive "benign" primary spine neoplasms: osteoblastoma, aneurysmal bone cyst, and giant cell tumor. Spine (Phila Pa 1976). 2009 Oct 15;34 (22 Suppl):S39-47 1 Shah RU, Lawrence C, Fickenscher KA, Shao L, Lowe LH. Imaging of pediatric pelvic neoplasms. Radiol Clin North Am. 2011;49(4):729-48 1 Avni FE, Guibaud L, Robert Y, Segers V, Ziereisen F, Delaet MH, Metens T. MR imaging of fetal sacrococcygeal teratoma: diagnosis and assessment. AJR Am J Roentgenol. 2002;178(1):179-83 Page 20 of 20