- Email: [email protected]
Intraosseous lipoma of the humeral head
Journal of Clinical Imaging 25 (2001) 428 – 431
Intraosseous lipoma of the humeral head MR appearance Tetsuji Yamamoto*, Toshihiro Akisue, Takashi Marui, Keiko Nagira, Shinichi Yoshiya, Masahiro Kurosaka Department of Orthopaedic Surgery, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan Received 10 March 2001
Abstract Intraosseous lipoma is the rarest benign primary bone tumor. We report a case of juxtaarticular intraosseous lipoma in the humeral head of a 50-year-old man. Roentgenographic, computed tomographic (CT), magnetic resonance (MR), scintigraphic, and histologic findings of this case are presented. D 2001 Elsevier Science Inc. All rights reserved. Keywords: Intraosseous lipoma; Humerus; Magnetic resonance imaging; Computed tomography
1. Introduction Intraosseous lipoma is the rarest benign bone neoplasm [1]. We report a patient with juxtaarticular intraosseous lipoma of the proximal humerus, who presented with shoulder pain. The multimodality imaging features including the pattern of gadolinium enhancement on magnetic resonance (MR) imaging are described.
2. Case report A 50-year-old man presented with a 2-month history of gradually increasing right shoulder pain. He complained of the pain when abducting the arm. The patient consulted an orthopaedic surgeon, and radiographic examination revealed a large osteolytic lesion in the right proximal humerus. He was referred to our institute for surgical treatment. He denied antecedent trauma to the shoulder. On physical examination, the range of motion of the affected shoulder was slightly limited in abduction and forward elevation. Mild tenderness was noted in the anterior aspect of the humeral head. Roentgenograms of the right shoulder
* Corresponding author. Tel.: +81-78-382-5985; fax: +81-78-3516930. E-mail address: [email protected] (T. Yamamoto).
showed a large well-defined osteolytic lesion with marginal sclerosis, involving the proximal metaphysis and epiphyseal equivalent (Fig. 1). There were calcified foci in the center of the lesion. Computed tomographic (CT) scans of the shoulder revealed an osteolytic lesion with low density in the anterolateral part of the humeral head (Fig. 2). Calcified areas were also observed within the lesion. There was mild cortical deformity in the anterolateral aspect of the humeral head, but no cortical breakthrough was observed. T1-weighted MR images revealed a lesion with slightly greater intensity than that of intramedullary fat and isosignal intensity to subcutaneous fat, containing a small area with low signal intensity (Fig. 3A). T2-weighted images also showed a lesion with isosignal intensity compared to subcutaneous fat (Fig. 3B). The majority of the area with low signal intensity on T1-weighted images was hyperintense on T2-weighted images. No abnormal signal intensity was observed in the rotator cuff or subacrominal bursa. On contrast-enhanced T1-weighted MR images, the area with low signal intensity on nonenhanced T1-weighted images was inhomogeneously enhanced. The signal intensity of the areas with high signal intensity on T1-weighted and T2-weighted images, however, did not change (Fig. 3C). A 99m technetium scintigraphic scan showed mildly increased isotope uptake in the right shoulder. The preoperative differential diagnosis included intraosseous lipoma and bone infarction. The patient subsequently underwent curettage and hydroxyapatite filling after excision of the
0899-7071/01/$ – see front matter D 2001 Elsevier Science Inc. All rights reserved. PII: S 0 8 9 9 - 7 0 7 1 ( 0 1 ) 0 0 3 3 7 - 0
T. Yamamoto et al. / Journal of Clinical Imaging 25 (2001) 428–431
Fig. 1. An anteroposterior radiograph of the right shoulder shows a large well-defined osteolytic lesion in the epiphyseal metaphyseal region of the proximal humerus. Calcification is present within the lesion.
lesion. Histopathologic examination revealed that the excised specimens consisted of mature adipose tissue and atrophic bone trabeculi (Fig. 4). There were foci of dystrophic calcification and areas of fibrovascular tissues with woven bone production (Fig. 5). These findings are consistent with those of intraosseous lipomas. The postoperative course was uneventful. The patient has been asymptomatic, and there has been no recurrence of the lesion 8 months postoperatively.
429
and swelling at the affected sites. Intraosseous lipomas affect both the axial and appendicular skeleton, and approximately 60% occur in the long bones [6]. Femurs and tibias are the most frequent long bones affected [2 –4,6,8,10]. Involvement of the humerus is less common [2,11,13]. When intraosseous lipomas arise in long bones, the metadiaphysis is the favored site [2,3,6,8,10,11,13,14]. Intraosseous lipomas in the juxtaarticular regions have been rarely reported. In the series by Milgram [2], only 2 of 66 intraosseous lipomas were located in the epiphyseal metaphyseal regions. Latham and Athanasou [4] reported on an intraosseous lipoma in the femoral head. Lesson et al. [5] presented a case of the disease involving the proximal fibular head. Roentgenographically, intraosseous lipomas show welldefined osteolytic lesions with sclerotic rims, sometimes accompanied by cortical expansion [1– 15]. Central mineralization is typically present within the lesions. Roentgenographic differential diagnosis includes bone infarction, fibrous dysplasia, enchondroma, chondromyxoid fibroma, aneurysmal bone cyst, and other benign tumors [5]. Milgram [2] subdivided intraosseous lipomas into three groups. Stage 1 lesions radiographically show a purely radiolucent zone with expansion of the original cortex. Stage 2 lesions demonstrate some of the same radiographic features as Stage 1 lesions but also contain localized regions of increased roentgenographic density due to calcified fat. Stage 3 lesions show considerable ossification around the calcified fat of the outer rim of the lesions. Histologically, Stage 1 lesions consists of solid tumors of viable lipocytes; Stage 2 consists of transitional cases with partial fat necrosis and focal calcification in addition to regions of viable lipocytes; Stage 3 consists of late cases in which the fat has been devitalized with variable degree of cyst formation,
3. Discussion Intraosseous lipoma is the rarest benign primary bone tumor. Unni [1] reported only seven cases among 11 087 bone tumors at the Mayo Clinic (less than 0.1%). A computer-based search of the English literature revealed approximately 200 cases of lipoma with intramedullary origin [2– 15]. The largest reported series by Milgram [2] includes 61 histologically confirmed solitary intraosseous lipomas. The majority of patients with this disease are middle aged [2,14]. There is a slight male predominance [2]. Many lesions are asymptomatic and appear only as incidental findings at routine roentgenographic evaluations. When symptoms occur, they usually consist of mild pain
Fig. 2. A CT scan of the shoulder shows an osteolytic lesion with fat attenuation in the anterolateral part of the humeral head.
430
T. Yamamoto et al. / Journal of Clinical Imaging 25 (2001) 428–431
Fig. 3. (A) An axial spin-echo T1-weighted MR image (TR/TE, 366/14) shows an intraosseous lipoma in the humeral head. The majority of the lesion was composed of areas with isosignal intensity to subcutaneous fat. There is a focal area with low signal intensity. (B) An axial spin-echo T2-weighted MR image (TR/TE, 2000/84) shows a hyperintense lesion. (C) A postcontrast T1-weighted image (TR/TE, 366/14) shows that the area with low signal intensity on nonenhanced T1-weighted image is inhomogeneously enhanced.
calcification, and reactive new bone formation of a characteristic morphology. Milgram [2] concluded that these roentgenographic and pathologic changes depended on the degree of involution of the lesions. The present case conforms to a Stage 2 lesion. The CT appearance of intraosseous lipomas is well described [5,12,13]. Intraosseous lipomas have well-defined osteolytic lesions with attenuation values equal to that of adipose tissues. Marginal sclerosis, cortical irregularity, and sclerosis around the lesions are often observed [5,13]. Central calcification within the lesions can be detected on CT. Cortical breakthrough is rarely observed [12]. MR features of intraosseous lipoma in long bones have been reported infrequently [3,6,11]. The signal intensity of the majority of the lesions is reported to be equal to that
of subcutaneous or intramedullary adipose tissue on both T1-weighted and T2-weighted MR images, which allows for a differential diagnosis. El-Atta et al. [3] and Levin et al. [6] suggested that the short-tau inversion recovery (STIR) sequence was useful for diagnosing intraosseous lipomas, because the extra signal intensity of the lesion is suppressed, indicating the presence of normal fat. In addition, some authors demonstrated intralesional hypointense areas on T1-weighted images, which were considered as dystrophic calcifications in necrotic fat tissues [3,6]. Levin et al. [6] also reported that these hypointense areas were calcifications because there was no evidence of enhancement after the administration of intravenous gadolinium. In the present case, the hypointense areas on T1-weighted images presented as a mixture of hyperintense and hypointense
T. Yamamoto et al. / Journal of Clinical Imaging 25 (2001) 428–431
431
vessels and woven bone formation. These reactive tissues can be observed in Stages 2 and 3 lesions [2,14]. The tissues are considered to be regenerative tissues following the fat necrosis. In summary, we report an uncommon case of intraosseous lipoma occurring in the juxtaarticular region of the shoulder. Multimodality imaging findings, including the pattern of gadolinium enhancement, in this case, were presented. The pattern of enhancement on MR imaging of the disease is probably variable depending on the disease stage. MR evaluation of a large series of patients with intraosseous lipomas will be required to determine the lesion-specific pattern of gadolinium enhancement. Fig. 4. Histologic findings of intraosseous lipoma. The majority of the lesion consisted of mature adipose tissues and atrophic bony trabeculi (hematoxylin and eosin, 100).
Fig. 5. A photomicrograph showing areas of central calcification (hematoxylin and eosin, 100).
areas on T2-weighted images and inhomogeneously enhanced after the administration of gadolinium. Histologic examination established these areas to be dystrophic calcification and reactive fibrous tissues with an abundance of
References [1] Unni KK. Lipoma and liposarcoma. In: Unni KK, editor. Dahlin’s bone tumors. General aspects and data on 11087 cases. Philadelphia: Lippincott-Raven, 1996. pp. 349 – 53. [2] Milgram JW. Intraosseous lipomas. A clinicopathologic study of 66 cases. Clin Orthop 1988;231:277 – 302. [3] El-Atta MA, Ivancevich SM, Braunstein EM. Intraosseous lipoma. Arthritis Rheum 1997;40:978 – 9. [4] Latham PD, Athanasou NA. Intraosseous lipoma within the femoral head. A case report. Clin Orthop 1991;265:228 – 32. [5] Leeson MC, Kay D, Smith BS. Intraosseous lipoma. Clin Orthop 1983;181:186 – 90. [6] Levin MF, Vellet AD, Munk PL, McLean CA. Intraosseous lipoma of the distal femur: MRI appearance. Skeletal Radiol 1996;25:82 – 4. [7] Ehara S, Kattapuram SV, Rosenberg AE. Case report 619. Intraosseous lipoma of the sacrum. Skeletal Radiol 1990;19:375 – 6. [8] Gero MJ, Kahn LB. Case report 498. Intraosseous lipoma of the distal end of the fibula with focal infarction. Skeletal Radiol 1988;17: 443 – 6. [9] Hall FM, Cohen RB, Grumbach K. Case report 377. Intraosseous lipoma (angiolipoma) of right third rib. Skeletal Radiol 1986;15: 401 – 3. [10] Goldman AB, Marcove RC, Huvos AG, Smith J. Case report 280. Intraosseous lipoma of the tibia. Skeletal Radiol 1984;12:209 – 12. [11] Noble JS, Leeson MC. Intraosseous lipoma of the humerus. Orthopedics 1992;15:51 – 4. [12] Buckley SL, Burkus JK. Intraosseous lipoma of the ileum. A case report. Clin Orthop 1988;228:297 – 301. [13] Barcelo M, Pathria MN, Abdul-Karim FM. Intraosseous lipoma. A clinicopathologic study of four cases. Arch Pathol Lab Med 1992; 116:947 – 50. [14] Chow LTC, Lee KC. Intraosseous lipoma. A clinicopathologic study of nine cases. Am J Surg Pathol 1992;16:401 – 10. [15] Beig-Roix V, Guinot-Tormo J, Risent-Martinez F, Aparisi-Rodriguez R, Ferrer-Jimenez R. Computed tomography of intraosseous lipoma of os calcis. Clin Orthop 1987;221:286 – 91.
Intraosseous lipoma of the humeral head MR appearance Tetsuji Yamamoto*, Toshihiro Akisue, Takashi Marui, Keiko Nagira, Shinichi Yoshiya, Masahiro Kurosaka Department of Orthopaedic Surgery, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan Received 10 March 2001
Abstract Intraosseous lipoma is the rarest benign primary bone tumor. We report a case of juxtaarticular intraosseous lipoma in the humeral head of a 50-year-old man. Roentgenographic, computed tomographic (CT), magnetic resonance (MR), scintigraphic, and histologic findings of this case are presented. D 2001 Elsevier Science Inc. All rights reserved. Keywords: Intraosseous lipoma; Humerus; Magnetic resonance imaging; Computed tomography
1. Introduction Intraosseous lipoma is the rarest benign bone neoplasm [1]. We report a patient with juxtaarticular intraosseous lipoma of the proximal humerus, who presented with shoulder pain. The multimodality imaging features including the pattern of gadolinium enhancement on magnetic resonance (MR) imaging are described.
2. Case report A 50-year-old man presented with a 2-month history of gradually increasing right shoulder pain. He complained of the pain when abducting the arm. The patient consulted an orthopaedic surgeon, and radiographic examination revealed a large osteolytic lesion in the right proximal humerus. He was referred to our institute for surgical treatment. He denied antecedent trauma to the shoulder. On physical examination, the range of motion of the affected shoulder was slightly limited in abduction and forward elevation. Mild tenderness was noted in the anterior aspect of the humeral head. Roentgenograms of the right shoulder
* Corresponding author. Tel.: +81-78-382-5985; fax: +81-78-3516930. E-mail address: [email protected] (T. Yamamoto).
showed a large well-defined osteolytic lesion with marginal sclerosis, involving the proximal metaphysis and epiphyseal equivalent (Fig. 1). There were calcified foci in the center of the lesion. Computed tomographic (CT) scans of the shoulder revealed an osteolytic lesion with low density in the anterolateral part of the humeral head (Fig. 2). Calcified areas were also observed within the lesion. There was mild cortical deformity in the anterolateral aspect of the humeral head, but no cortical breakthrough was observed. T1-weighted MR images revealed a lesion with slightly greater intensity than that of intramedullary fat and isosignal intensity to subcutaneous fat, containing a small area with low signal intensity (Fig. 3A). T2-weighted images also showed a lesion with isosignal intensity compared to subcutaneous fat (Fig. 3B). The majority of the area with low signal intensity on T1-weighted images was hyperintense on T2-weighted images. No abnormal signal intensity was observed in the rotator cuff or subacrominal bursa. On contrast-enhanced T1-weighted MR images, the area with low signal intensity on nonenhanced T1-weighted images was inhomogeneously enhanced. The signal intensity of the areas with high signal intensity on T1-weighted and T2-weighted images, however, did not change (Fig. 3C). A 99m technetium scintigraphic scan showed mildly increased isotope uptake in the right shoulder. The preoperative differential diagnosis included intraosseous lipoma and bone infarction. The patient subsequently underwent curettage and hydroxyapatite filling after excision of the
0899-7071/01/$ – see front matter D 2001 Elsevier Science Inc. All rights reserved. PII: S 0 8 9 9 - 7 0 7 1 ( 0 1 ) 0 0 3 3 7 - 0
T. Yamamoto et al. / Journal of Clinical Imaging 25 (2001) 428–431
Fig. 1. An anteroposterior radiograph of the right shoulder shows a large well-defined osteolytic lesion in the epiphyseal metaphyseal region of the proximal humerus. Calcification is present within the lesion.
lesion. Histopathologic examination revealed that the excised specimens consisted of mature adipose tissue and atrophic bone trabeculi (Fig. 4). There were foci of dystrophic calcification and areas of fibrovascular tissues with woven bone production (Fig. 5). These findings are consistent with those of intraosseous lipomas. The postoperative course was uneventful. The patient has been asymptomatic, and there has been no recurrence of the lesion 8 months postoperatively.
429
and swelling at the affected sites. Intraosseous lipomas affect both the axial and appendicular skeleton, and approximately 60% occur in the long bones [6]. Femurs and tibias are the most frequent long bones affected [2 –4,6,8,10]. Involvement of the humerus is less common [2,11,13]. When intraosseous lipomas arise in long bones, the metadiaphysis is the favored site [2,3,6,8,10,11,13,14]. Intraosseous lipomas in the juxtaarticular regions have been rarely reported. In the series by Milgram [2], only 2 of 66 intraosseous lipomas were located in the epiphyseal metaphyseal regions. Latham and Athanasou [4] reported on an intraosseous lipoma in the femoral head. Lesson et al. [5] presented a case of the disease involving the proximal fibular head. Roentgenographically, intraosseous lipomas show welldefined osteolytic lesions with sclerotic rims, sometimes accompanied by cortical expansion [1– 15]. Central mineralization is typically present within the lesions. Roentgenographic differential diagnosis includes bone infarction, fibrous dysplasia, enchondroma, chondromyxoid fibroma, aneurysmal bone cyst, and other benign tumors [5]. Milgram [2] subdivided intraosseous lipomas into three groups. Stage 1 lesions radiographically show a purely radiolucent zone with expansion of the original cortex. Stage 2 lesions demonstrate some of the same radiographic features as Stage 1 lesions but also contain localized regions of increased roentgenographic density due to calcified fat. Stage 3 lesions show considerable ossification around the calcified fat of the outer rim of the lesions. Histologically, Stage 1 lesions consists of solid tumors of viable lipocytes; Stage 2 consists of transitional cases with partial fat necrosis and focal calcification in addition to regions of viable lipocytes; Stage 3 consists of late cases in which the fat has been devitalized with variable degree of cyst formation,
3. Discussion Intraosseous lipoma is the rarest benign primary bone tumor. Unni [1] reported only seven cases among 11 087 bone tumors at the Mayo Clinic (less than 0.1%). A computer-based search of the English literature revealed approximately 200 cases of lipoma with intramedullary origin [2– 15]. The largest reported series by Milgram [2] includes 61 histologically confirmed solitary intraosseous lipomas. The majority of patients with this disease are middle aged [2,14]. There is a slight male predominance [2]. Many lesions are asymptomatic and appear only as incidental findings at routine roentgenographic evaluations. When symptoms occur, they usually consist of mild pain
Fig. 2. A CT scan of the shoulder shows an osteolytic lesion with fat attenuation in the anterolateral part of the humeral head.
430
T. Yamamoto et al. / Journal of Clinical Imaging 25 (2001) 428–431
Fig. 3. (A) An axial spin-echo T1-weighted MR image (TR/TE, 366/14) shows an intraosseous lipoma in the humeral head. The majority of the lesion was composed of areas with isosignal intensity to subcutaneous fat. There is a focal area with low signal intensity. (B) An axial spin-echo T2-weighted MR image (TR/TE, 2000/84) shows a hyperintense lesion. (C) A postcontrast T1-weighted image (TR/TE, 366/14) shows that the area with low signal intensity on nonenhanced T1-weighted image is inhomogeneously enhanced.
calcification, and reactive new bone formation of a characteristic morphology. Milgram [2] concluded that these roentgenographic and pathologic changes depended on the degree of involution of the lesions. The present case conforms to a Stage 2 lesion. The CT appearance of intraosseous lipomas is well described [5,12,13]. Intraosseous lipomas have well-defined osteolytic lesions with attenuation values equal to that of adipose tissues. Marginal sclerosis, cortical irregularity, and sclerosis around the lesions are often observed [5,13]. Central calcification within the lesions can be detected on CT. Cortical breakthrough is rarely observed [12]. MR features of intraosseous lipoma in long bones have been reported infrequently [3,6,11]. The signal intensity of the majority of the lesions is reported to be equal to that
of subcutaneous or intramedullary adipose tissue on both T1-weighted and T2-weighted MR images, which allows for a differential diagnosis. El-Atta et al. [3] and Levin et al. [6] suggested that the short-tau inversion recovery (STIR) sequence was useful for diagnosing intraosseous lipomas, because the extra signal intensity of the lesion is suppressed, indicating the presence of normal fat. In addition, some authors demonstrated intralesional hypointense areas on T1-weighted images, which were considered as dystrophic calcifications in necrotic fat tissues [3,6]. Levin et al. [6] also reported that these hypointense areas were calcifications because there was no evidence of enhancement after the administration of intravenous gadolinium. In the present case, the hypointense areas on T1-weighted images presented as a mixture of hyperintense and hypointense
T. Yamamoto et al. / Journal of Clinical Imaging 25 (2001) 428–431
431
vessels and woven bone formation. These reactive tissues can be observed in Stages 2 and 3 lesions [2,14]. The tissues are considered to be regenerative tissues following the fat necrosis. In summary, we report an uncommon case of intraosseous lipoma occurring in the juxtaarticular region of the shoulder. Multimodality imaging findings, including the pattern of gadolinium enhancement, in this case, were presented. The pattern of enhancement on MR imaging of the disease is probably variable depending on the disease stage. MR evaluation of a large series of patients with intraosseous lipomas will be required to determine the lesion-specific pattern of gadolinium enhancement. Fig. 4. Histologic findings of intraosseous lipoma. The majority of the lesion consisted of mature adipose tissues and atrophic bony trabeculi (hematoxylin and eosin, 100).
Fig. 5. A photomicrograph showing areas of central calcification (hematoxylin and eosin, 100).
areas on T2-weighted images and inhomogeneously enhanced after the administration of gadolinium. Histologic examination established these areas to be dystrophic calcification and reactive fibrous tissues with an abundance of
References [1] Unni KK. Lipoma and liposarcoma. In: Unni KK, editor. Dahlin’s bone tumors. General aspects and data on 11087 cases. Philadelphia: Lippincott-Raven, 1996. pp. 349 – 53. [2] Milgram JW. Intraosseous lipomas. A clinicopathologic study of 66 cases. Clin Orthop 1988;231:277 – 302. [3] El-Atta MA, Ivancevich SM, Braunstein EM. Intraosseous lipoma. Arthritis Rheum 1997;40:978 – 9. [4] Latham PD, Athanasou NA. Intraosseous lipoma within the femoral head. A case report. Clin Orthop 1991;265:228 – 32. [5] Leeson MC, Kay D, Smith BS. Intraosseous lipoma. Clin Orthop 1983;181:186 – 90. [6] Levin MF, Vellet AD, Munk PL, McLean CA. Intraosseous lipoma of the distal femur: MRI appearance. Skeletal Radiol 1996;25:82 – 4. [7] Ehara S, Kattapuram SV, Rosenberg AE. Case report 619. Intraosseous lipoma of the sacrum. Skeletal Radiol 1990;19:375 – 6. [8] Gero MJ, Kahn LB. Case report 498. Intraosseous lipoma of the distal end of the fibula with focal infarction. Skeletal Radiol 1988;17: 443 – 6. [9] Hall FM, Cohen RB, Grumbach K. Case report 377. Intraosseous lipoma (angiolipoma) of right third rib. Skeletal Radiol 1986;15: 401 – 3. [10] Goldman AB, Marcove RC, Huvos AG, Smith J. Case report 280. Intraosseous lipoma of the tibia. Skeletal Radiol 1984;12:209 – 12. [11] Noble JS, Leeson MC. Intraosseous lipoma of the humerus. Orthopedics 1992;15:51 – 4. [12] Buckley SL, Burkus JK. Intraosseous lipoma of the ileum. A case report. Clin Orthop 1988;228:297 – 301. [13] Barcelo M, Pathria MN, Abdul-Karim FM. Intraosseous lipoma. A clinicopathologic study of four cases. Arch Pathol Lab Med 1992; 116:947 – 50. [14] Chow LTC, Lee KC. Intraosseous lipoma. A clinicopathologic study of nine cases. Am J Surg Pathol 1992;16:401 – 10. [15] Beig-Roix V, Guinot-Tormo J, Risent-Martinez F, Aparisi-Rodriguez R, Ferrer-Jimenez R. Computed tomography of intraosseous lipoma of os calcis. Clin Orthop 1987;221:286 – 91.