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Year : 2005  |  Volume : 15  |  Issue : 4  |  Page : 481-484
Imaging features of osteoid osteoma in plain radiograph, CT and MR : A case report and review of literatures

Primus, GS Road, Bhangagarh, Guwahati - 5, Assam, India

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Keywords: Osteoid, Osteoma, Skeletal, MR, CT

How to cite this article:
Goswami P, Medhi N, Sarma P K, Das H S, Hazarika P. Imaging features of osteoid osteoma in plain radiograph, CT and MR : A case report and review of literatures. Indian J Radiol Imaging 2005;15:481-4

How to cite this URL:
Goswami P, Medhi N, Sarma P K, Das H S, Hazarika P. Imaging features of osteoid osteoma in plain radiograph, CT and MR : A case report and review of literatures. Indian J Radiol Imaging [serial online] 2005 [cited 2021 Feb 27];15:481-4. Available from:

   Introduction Top

Osteoid osteoma is a benign skeletal neoplasm, observed most frequently in young patients. In most of the patients osteoid osteoma produces typical clinical symptoms and imaging features that are usually sufficient to arrive at a correct diagnosis. We report plain radiograph, CT and MR features of osteoid osteoma in a young patient with short review of literatures.

   Case report Top

A twenty five years old man presented with complaints of continuous dull pain in the right leg for over one year. The pain was ameliorated after taking analgesics. There was no history of any preceding trauma. Local clinical examination revealed no significant finding except mild tenderness at the middle part of right leg medially. No symptoms and signs of a systemic process was noted. Relevant routine laboratory tests were found to be normal. Plain radiograph of right leg was obtained which revealed a small radiolucent nidus in the medial aspect of midshaft of tibia surrounded by bone sclerosis and cortical thickening caused by subperiosteal and endosteal new bone formation [Figure - 1]. The size of the radiolucent nidus was approximately 3 mm. Clinical history and plain radiographic findings favoured the diagnosis of osteoid osteoma. Axial plain CT of the part was performed which showed the partially calcified nidus, mature periosteal bone formation and the location of the original cortex [Figure - 2]. CT demonstrated the nidus more precisely which was located on the surface of the original cortex of the tibia and buried by periosteal bone formation. Transverse T2 - weighted spin echo and T2 - weighted fat suppressed MR images were obtained. Transaxial T2 weighted images showed the nidus with central calcification, periosteal bone formation and marrow edema [Figure - 3]. T2-weighted fat suppressed images also revealed the nidus clearly along with thickened cortex and hyperintense signal intensity in the juxtanidal marrow and soft tissue, suggesting marrow and soft tissue edema [Figure - 4]. The CT and MR findings were consistent with osteoid osteoma. The patient underwent surgery and the tumor was excised [Figure - 5]. Histopathological examination of the specimen confirmed the diagnosis of osteoid

   Discussion Top

The term osteoid osteoma was introduced by Jaffe in 1935 to describe a benign osteoblastic tumor with distinctive histologic abnormalities consisting of a central core of vascular osteoid tissue and a peripheral zone of sclerotic bone. Osteoid osteoma has been a subject of debate regarding its precise relationship to a second lesion of the bone, osteoblastoma. The differentiation between osteoid osteoma and osteoblastoma has been based primarily on the size of the lesion (i.e., the size of the nidus). Although some investigators have used 1.0 cm as the upper limit of the size of an osteoid osteoma, others have used 1.5 cm for this purpose and still others designate lesions that have been as large as 2.5 cm as osteoid osteoma [1]. Some authors believe that both conditions are probably variation of the same disease process, depending on the anatomical site and type of bone affected [2].

Patients are usually young, and there is a strong male predominance. Pain is the most common symptom, which is worse at night. The pain is usually relieved by aspirin or other analgesics [1],[2]. The location of osteoid osteoma is categorized as intracortical, subperiosteal, endosteal, or medullary. The most common affected sites are femur, tibia and humerus [3]. The lesion is most commonly located in the cortex of long bones where it is associated with dense, fusiform, reactive sclerosis. Less often, it may be cancellous, where reactive osteosclerosis is usually less intense and may be distant from the lesion. Cancellous lesions are frequently intraarticular (most often in the hip) and may be associated with synovitis and joint effusion [4]. Osteoid osteomas occurring in a subperiosteal or surface location are not rare. Indeed, many osteoid osteoma arising in a tubular bone possibly originate in a subperiosteal site and later appear as anintracortical lesion. This site of origin appears to relate principally to continual remodeling of bone with subperiosteal deposition and endosteal erosion [3]. Subperiosteal osteoid osteomas may produce atypical radiographic and histopathologic features, and unusual reactive periostitis may suggest other diagnosis [5].

Conventional radiography is an effective initial technique in the evaluation of patients in whom an osteoid osteoma is suspected. The classic radiographic appearance of a centrally located, small radiolucent area, representing the nidus, surrounded by a zone of uniform bone sclerosis and cortical thickening caused by endosteal and subperiosteal new bone formation is virtually diagnostic of this lesion. The nidus itself may be uniformly radiolucent or contain variable amount of calcification. The nidus is almost always less than 1 cm in diameter and oval or round in configuration. These characteristics have diagnostic significance and generally allow differentiation of an osteoid osteoma from a stress fracture ( which is accompanied by a linear, radiolucent cortical area) and a osteoblastoma (which is commonly a larger lesion). In rare circumstances, a single osteoid osteoma may contain more than one nidus, or more than one osteoid osteoma, each with its own nidus, may be found in the same bone or neighbouring bones. As a general rule, the nidus is located in the centre of the sclerotic lesion, but its precise delineation may require additional imaging technique such as CT [1].

CT is the best imaging modality for diagnosis of osteoid osteoma. CT is far more accurate than MR imaging in detection of the osteoid osteoma nidus [6]. CT has largely replaced conventional radiography in the imaging evaluation of osteiod osteomas. In instances in which the lesion is small or not readily apparent on conventional radiography, CT may be required. The choice of adequate window settings for visualization of cortical bone is essential for accurate CT documentation of the nidus. CT is most valuable in defining osteoid osteomas in the spine, osseous pelvis, femoral neck and occasionally, other sites [1]. CT is useful to identify and precisely locate the lesion and to provide guidance for percutaneous localization and treatment [4].

MR imaging is generally considered less useful than CT for detection of osteoid osteoma nidus. MR imaging is better than CT in showing intramedullary and soft tissue changes associated with osteoid osteoma [6]. Signal intensity of the nidus, marrow and soft tissue edema on MR imaging are variable. Perinidal edema is most pronounced in younger patients and has no apparent relation to drug therapy. MR imaging can reliably demonstrate the nidus of an osteoid osteoma, which has a variable appearance related to its position relative to the cortex of the bone, size and the amount of calcification or fibrous tissue present. MR imaging is considered better than CT in diagnosing osteoid osteoma, when the nidus is in a cancellous location. In this location CT may fail to demonstrate the lesion, due to lack of perinidal density alteration. On MR images, marrow edema in the vicinity of the lesion improves the conspicuity of the nidus [7]. MR imaging findings in cases of osteoid osteoma may simulate those of a malignant tumor or osteomyelitis as a result of the presence of marrow and soft tissue edema and even a soft tissue mass. Reliance on MR imaging alone may lead to misdiagnosis. Optimization of MR technique is crucial in reducing the risk of missing the diagnosis. Unexplained areas of bone marrow edema in particular require further imaging (preferably CT) to exclude an osteoid osteoma [8].

In our patient, sclerosis and cortical thickening due to subperiosteal bone formation were noted in the plain radiograph. The radiolucent nidus was faintly visualized. The calcification within the nidus could not be clearly seen in the plain radiograph. The location of the nidus, intranidal calcification, sclerosis, mature periosteal bone formation and location of original cortex were precisely demonstrated by CT. MR imaging also clearly showed the partially calcified nidus and associated cortical thickening. In addition, MR images revealed mild marrow and soft tissue edema in the vicinity of the nidus, which could not be seen in CT.

   References Top

1.Resnick D, Kyriakos 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. Vol. 4. Philadelphia : W.B Saunders, 1997 : 3767- 3786.  Back to cited text no. 1    
2.Black JA, Levick RK, Sharrard WJ. Osteoid osteoma and benign osteoblastoma in childhood. Arch. Dis. Child. 1979 ; 54 : 459 - 464.  Back to cited text no. 2    
3.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 1998; 170 : 609 - 614.  Back to cited text no. 3    
4.Kransdorf MJ, Stull MA, FW Gilkey, Moser RP Jr. Osteoid osteoma. RadioGraphics 1991; 11 : 671 - 696.  Back to cited text no. 4    
5.Shankman S, Desai P, Beltran J. Subperiosteal osteoid osteoma : radiographic and pathologic manifestations. Skeletal Radiol 1997 ; 26 (8) : 457 - 462.  Back to cited text no. 5    
6.Assoun J, Richardi G, Railhac JJ et al. Osteoid osteoma : MR imaging versus CT. Radiology 1994; 191 : 217 - 223.  Back to cited text no. 6    
7.Spouge AR, Thain LM. Osteoid osteoma : MR imaging revisited. Clin. Imaging 2000 ; 24(1) : 19 - 27.  Back to cited text no. 7    
8.Davies M, Cassar-Pullicino VN, Davies AM, McCall IW, Tyrrell PN. The diagnostic accuracy of MR imaging in osteoid osteoma. Skeletal Radiol 2002; 31(10) : 559 - 569.  Back to cited text no. 8    

Correspondence Address:
P Goswami
Primus, GS Road, Bhangagarh, Guwahati - 5, Assam
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0971-3026.28779

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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]

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