Answer for BIR CoW 16 Oct 2022
Osteoid osteoma
Findings
Well defined low attenuation noted on posterior 1/3 of vertebral body of L5 with central high attenuation foci
Relatively well circumscribed focal lesion noted in posterosuperior corner of L5 vertebral body causing minimal posterior cortical expansion which appears hypointense on T2 WI with peripheral hypointense rim on T1WI
No evidence of soft tissue and no evidence of spinal canal compromise
Lesion measures 11x10mm
On dynamic contrast administration above mentioned focal lesion shows prominent vascular blush with central foci of non enhancing area
Possible arterial feeder from 3rd right lumbar artery
Impression
Relatively well circumscribed focal lesion in posterosuperior corner of L5 vertebral body causing minimal posterior cortical expansion
Dynamic contrast administration reveals focal lesion shows prominent vascular blush with central foci of non enhancing area.
Above mentioned Features suggestive of osteiod osteoma
Discussion
Typical radiographic findings of osteoid osteoma include an intracortical nidus, which may display a variable amount of mineralization, accompanied by cortical thickening and reactive sclerosis in a long bone shaft. The radiolucent focus often is referred to as the nidus because the focus usually is located in the center of an area of reactive sclerosis. The nidus is round or oval and usually smaller than 2 cm . Bone density may be decreased because of disuse due to pain
At CT, the nidus is well defined and round or oval with low attenuation . An area of high attenuation may be seen centrally, a finding that represents mineralized osteoid
MR imaging depicts not only the nidus and accompanying sclerosis but also adjacent bone marrow and articular abnormalities . The nidus has low to intermediate signal intensity on T1-weighted images and variable signal intensity on T2-weighted images, depending on the amount of mineralization present in the center of the nidus. Edema in adjacent bone marrow and soft tissue and joint effusion also may be seen . Because of the recent increases in spatial resolution, a partially mineralized nidus generally has a targetlike appearance, with a high-signal-intensity periphery (the unmineralized part)a central area of low signal intensity (the mineralized portion). The nidus also may demonstrate strong enhancement after the administration of gadolinium-based contrast material
The most common location of spinal osteoid osteoma is the lumbar segment , followed by the cervical segment and the thoracic segment. The sacrum is the least commonly affected spinal segment . In most cases, the nidus is located in the neural arch . Patients with spinal osteoid osteoma present with radicular pain, gait disturbance, limb atrophy, and painful scoliosis
Characteristic MR imaging features of spinal osteoid osteoma
are a nidus in the neural arch and bone marrow edema in the involved pedicle and lamina that extends to the posterolateral vertebral body
Conditions That Mimic Osteoid Osteoma
localized cortical thickening, reactive sclerosis surrounding an osteolytic lesion, bone marrow edema. These conditions include stress fracture, intracortical abscess, intracortical hemangioma, chondroblastoma, osteoblastoma, and compensatory hypertrophy of the pedicle. To distinguish these entities from osteoid osteoma, it is helpful to be familiar with the imaging findings specific to the mimics and recognize the lack of a typical nidus
References
1. Radiologic Diagnosis of Osteoid Osteoma: From Simple to Challenging Findings Lee EH, Shafi M, Hui JH. Osteoid osteoma: a current review. J Pediatr Orthop 2006;26(5):695–700.
2. Cerase A, Priolo F. Skeletal benign bone-forming lesions. Eur J Radiol 1998;27(suppl 1):S91–S97.
3. Jaffe HL. Osteoid-osteoma. Proc R Soc Med 1953; 46(12):1007–1012.
4. Resnick D, Kyrriakos M, Greenway GD. Tumors and tumor-like lesions of bone: imaging and pathology of specific lesions. In: Resnick D, ed. Diagnosis of bone and joint disorders. 4th ed. Philadelphia, Pa: Saunders, 2002; 3763–3786.
5. Resnick D, Kyrriakos M, Greenway GD. Tumors and tumor-like lesions of bone: imaging and pathology of specific lesions. In: Resnick D, Kransdorf MJ, eds. Bone and joint imaging. 3rd ed. Philadelphia, Pa: Saunders, 2005; 1120–1130.
6. Kransdorf MJ, Stull MA, Gilkey FW, Moser RP Jr. Osteoid osteoma. RadioGraphics 1991;11(4): 671–696. 7. Kayser F, Resnick D, Haghighi P, et al. Evidence of the subperiosteal origin of osteoid osteomas in tubular bones: analysis by CT and MR imaging. AJR Am J Roentgenol 1
Findings
Well defined low attenuation noted on posterior 1/3 of vertebral body of L5 with central high attenuation foci
Relatively well circumscribed focal lesion noted in posterosuperior corner of L5 vertebral body causing minimal posterior cortical expansion which appears hypointense on T2 WI with peripheral hypointense rim on T1WI
No evidence of soft tissue and no evidence of spinal canal compromise
Lesion measures 11x10mm
On dynamic contrast administration above mentioned focal lesion shows prominent vascular blush with central foci of non enhancing area
Possible arterial feeder from 3rd right lumbar artery
Impression
Relatively well circumscribed focal lesion in posterosuperior corner of L5 vertebral body causing minimal posterior cortical expansion
Dynamic contrast administration reveals focal lesion shows prominent vascular blush with central foci of non enhancing area.
Above mentioned Features suggestive of osteiod osteoma
Discussion
Typical radiographic findings of osteoid osteoma include an intracortical nidus, which may display a variable amount of mineralization, accompanied by cortical thickening and reactive sclerosis in a long bone shaft. The radiolucent focus often is referred to as the nidus because the focus usually is located in the center of an area of reactive sclerosis. The nidus is round or oval and usually smaller than 2 cm . Bone density may be decreased because of disuse due to pain
At CT, the nidus is well defined and round or oval with low attenuation . An area of high attenuation may be seen centrally, a finding that represents mineralized osteoid
MR imaging depicts not only the nidus and accompanying sclerosis but also adjacent bone marrow and articular abnormalities . The nidus has low to intermediate signal intensity on T1-weighted images and variable signal intensity on T2-weighted images, depending on the amount of mineralization present in the center of the nidus. Edema in adjacent bone marrow and soft tissue and joint effusion also may be seen . Because of the recent increases in spatial resolution, a partially mineralized nidus generally has a targetlike appearance, with a high-signal-intensity periphery (the unmineralized part)a central area of low signal intensity (the mineralized portion). The nidus also may demonstrate strong enhancement after the administration of gadolinium-based contrast material
The most common location of spinal osteoid osteoma is the lumbar segment , followed by the cervical segment and the thoracic segment. The sacrum is the least commonly affected spinal segment . In most cases, the nidus is located in the neural arch . Patients with spinal osteoid osteoma present with radicular pain, gait disturbance, limb atrophy, and painful scoliosis
Characteristic MR imaging features of spinal osteoid osteoma
are a nidus in the neural arch and bone marrow edema in the involved pedicle and lamina that extends to the posterolateral vertebral body
Conditions That Mimic Osteoid Osteoma
localized cortical thickening, reactive sclerosis surrounding an osteolytic lesion, bone marrow edema. These conditions include stress fracture, intracortical abscess, intracortical hemangioma, chondroblastoma, osteoblastoma, and compensatory hypertrophy of the pedicle. To distinguish these entities from osteoid osteoma, it is helpful to be familiar with the imaging findings specific to the mimics and recognize the lack of a typical nidus
References
1. Radiologic Diagnosis of Osteoid Osteoma: From Simple to Challenging Findings Lee EH, Shafi M, Hui JH. Osteoid osteoma: a current review. J Pediatr Orthop 2006;26(5):695–700.
2. Cerase A, Priolo F. Skeletal benign bone-forming lesions. Eur J Radiol 1998;27(suppl 1):S91–S97.
3. Jaffe HL. Osteoid-osteoma. Proc R Soc Med 1953; 46(12):1007–1012.
4. Resnick D, Kyrriakos M, Greenway GD. Tumors and tumor-like lesions of bone: imaging and pathology of specific lesions. In: Resnick D, ed. Diagnosis of bone and joint disorders. 4th ed. Philadelphia, Pa: Saunders, 2002; 3763–3786.
5. Resnick D, Kyrriakos M, Greenway GD. Tumors and tumor-like lesions of bone: imaging and pathology of specific lesions. In: Resnick D, Kransdorf MJ, eds. Bone and joint imaging. 3rd ed. Philadelphia, Pa: Saunders, 2005; 1120–1130.
6. Kransdorf MJ, Stull MA, Gilkey FW, Moser RP Jr. Osteoid osteoma. RadioGraphics 1991;11(4): 671–696. 7. Kayser F, Resnick D, Haghighi P, et al. Evidence of the subperiosteal origin of osteoid osteomas in tubular bones: analysis by CT and MR imaging. AJR Am J Roentgenol 1
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!