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Radiological evaluation of bilateral intraosseous calcaneal lipoma in various stages of involution
European Journal of Radiology Extra 78 (2011) e57–e59
Contents lists available at ScienceDirect
European Journal of Radiology Extra journal homepage: intl.elsevierhealth.com/journals/ejrex
Radiological evaluation of bilateral intraosseous calcaneal lipoma in various stages of involution Shahina Bano a,∗ , Sachchida Nand Yadav b,1 , Vikas Chaudhary c,2 , Vijay Kumar Jain d,3 a
Department of Radiodiagnosis, Govind Ballabh Pant Hospital and Maulana Azad Medical College, Room No: 603, New Resident Doctor’s Hostel, New Delhi 110002, India Department of Radiodiagnosis, Dr. Ram Manohar Lohia Hospital & PGIMER, 208-D, Curzon Road Apartment, Delhi 110001, India Department of Radiodiagnosis, Employees’ State Insurance Corporation (ESIC) Model Hospital, Gurgaon, Room No: 27, New Resident Block, Lady Hardinge Medical College, New Delhi 110001, India d Department of Orthopedics, Dr. Ram Manohar Lohia Hospital & PGIMER, New Delhi 110001, India b c
a r t i c l e
i n f o
Article history: Received 6 November 2010 Received in revised form 21 January 2011 Accepted 28 January 2011
Keywords: Bilateral involuted intraosseous calcaneal lipoma Conventional radiograph Computed tomography Magnetic resonance imaging
a b s t r a c t Bilateral intraosseous lipoma is an unusual diagnosis. Radiological appearance depends on the stage due to evolutionary changes within the tumor. This report describes the imaging features of pathologically proven bilateral intraosseous calcaneal lipoma, showing the complete spectrum of evolutionary change, in the form of intralesional cyst, hemorrhage, fat necrosis, dystrophic calcification and woven bone formation, occurring simultaneously in the same patient. © 2011 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Occurrence of lipoma in bilateral calcaneus is extremely rare. To our knowledge, four cases of bilateral calcaneal lipoma and only two case of lipoma with hemorrhage have been described in the literature [1,2]. However, the various patterns of evolutionary change (as seen in our case) in the form of intralesional cyst, hemorrhage, fat necrosis, dystrophic calcification and woven bone formation simultaneously, in the same patient have not been reported till date. 2. Case report A 46-year-old male, football player, presented with intermittent pain and tenderness in bilateral heels of 6 month’s duration, which increased on weight bearing or sports activity. There was no history of trauma.
∗ Corresponding author. Mobile: +91 9868244786. E-mail addresses: dr [email protected] (S. Bano), sn [email protected] (S.N. Yadav), dr [email protected] (V. Chaudhary), dr [email protected] (V.K. Jain). 1 Mobile: +91 9868874466. 2 Department of Radiodiagnosis, Employee’s State Insurance Corporation (ESIC) Model Hospital, Gurgaon, Haryana, India. Mobile: +91 9968338008. 3 Mobile: +91 9968277722. 1571-4675/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2011.01.015
Conventional lateral radiographs of bilateral calcaneus showed sharply defined lytic lesions with sclerotic borders at the base of calcaneus neck (Fig. 1). Axial CT demonstrated peripheral zone of fat density, and central area of soft tissue density. Bilateral mild medullary expansion was noted without any cortical breach (Fig. 2). On T1- and T2-weighted MR images (Fig. 3A and B) both the lesions demonstrated peripheral fatty zone of high (on T1WI) and intermediate (on T2WI) signal intensity; with central area of mixed signal intensity (hematoma) in right calcaneum; and myxoid degeneration with cyst formation in left calcaneum (cyst within cyst appearance). In both the lesions, a low signal intensity rim (woven bone-fibrovascular tissue complex) was detected at the junction of peripheral and central zone, on T2*GRE images (Fig. 3C). STIR imaging suppressed the peripheral fat, but the central area replaced by cystic degeneration and the hemorrhage appeared hyperintense (Fig. 3D). On T1-weighted fat suppression post gadolinium image, the outer capsules and the interface between the outer fatty layer and the inner hematoma/fluid component demonstrated rim enhancement (Fig. 3E). On the basis of above imaging findings, the diagnosis of bilateral intraosseous calcaneal lipoma, showing hemorrhage in right calcaneus; and variable degree of cyst formation in left calcaneus, was made. Because of the benignancy and the virtually diagnostic appearance of the lesion radiographically, a bone biopsy was not performed. Due to large symptomatic lesions, the patient
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S. Bano et al. / European Journal of Radiology Extra 78 (2011) e57–e59
Fig. 1. Lateral X-ray bilateral calcaneus shows well defined radiolucent lesions (thin large arrow) at ward’s triangles, with central oval shaped area showing thin peripheral rim of increased density (thick small arrow).
subsequently underwent surgical curettage and bone grafting. Histopathological examination confirmed the radiological diagnosis. Post-op recovery was excellent. 3. Discussion Intraosseous lipoma primarily affects lower extremities especially femoral metaphysics and neck of calcaneus. A primary lesion of intraosseous lipoma consists of mature lipocytes and frequently involutes spontaneously through the processes of infarction, calcification, cyst formation, fat necrosis, myxoid degeneration and reactive bone formation. Since these involutional changes lead to characteristic radiological and histopathological features, Milgram subdivided these entities into three stages – Stage I: solid tumour of viable lipocytes. Stage II: mixed pattern of viable and necrotic lipocytes along with focal areas of dystrophic calcification. Stage III: near complete/completely necrotic fat, calcification, variable degrees of cyst formation, and reactive new bone formation. The progression from stage 1 to stage 3 is caused by ischemia and infarction within the lesion [3]. Cross-sectional imaging findings are highly suggestive and avoids a biopsy. On CT, an intraosseous lipoma is seen as a well-circumscribed lytic lesion of fat density, with heterogeneity
Fig. 2. Axial CT of bilateral calcaneus demonstrates low density lesions (single large arrow) showing negative Hounsfield unit consistent with fat density (right foot, −130 HU; left foot, −90 HU), and central area (star) of soft tissue density (right foot, +35 HU; left foot, +21 HU) with peripheral rim calcification (thick small arrow). Multiple thin intervening trabeculae (double large arrow) are seen within both the lesions.
Fig. 3. (A) Sagittal T1-weighted MR images show right calcaneus demonstrating peripheral rim of high signal corresponding to fat (large arrow), and intermediate signal intensity in central portion of lesion consistent with hemorrhage (small thick arrow), while the left calcaneus shows outer layer of hyperintense fat (large arrow), surrounding the middle zone intermediate signal intensity rim consistent with ongoing fat necrosis/myxoid degeneration (small thick arrow), and central low signal intensity nidus consistent with fluid (star). (B) Corresponding T2-weighted Sagittal MR images show right calcaneus hematoma with mixed high and low signal intensity (small thick arrow), while the lesion in left calcaneus demonstrated cyst within cyst appearance due to presence of hypointense rim of calcification (thin long arrow) between high signal intensity central fluid (star) and middle zone ongoing fat necrosis (small thick arrow). (C) Coronal T2* GRE images show circumferential rim of low signal intensity at the margin of bilateral central lesions, and at the periphery of mid-zone cystic area in left calcaneus suggests woven bony trabeculae/calcification (white arrow). (D) Corresponding coronal inversion recovery (STIR) image confirms the presence of fat due to suppression of outer rim (thin white arrow). The central fluid/fat necrosis (star/thick black arrow) and hematoma (thin black arrow) demonstrate high signal intensity. (E) Post-contrast fat suppression T1-weighted coronal images show rim enhancement of the fibrovascular tissue at the interface between the outer fatty layer and the inner hematoma/fluid component (thin black arrow). The capsule of bilateral lesions also shows subtle, thin peripheral rim enhancement (thin white arrow).
S. Bano et al. / European Journal of Radiology Extra 78 (2011) e57–e59
resulting from fat necrosis, hemorrhage and dystrophic calcification. MRI is an excellent method for demonstrating fatty tissue which appears high signal intensity on T1W and intermediate signal intensity on T2W fast spin echo sequences. The areas of intermediate signal intensity on T1-weighted and high signal intensity on T2-weighted sequences are suggestive of ongoing fat necrosis, later resulting in cyst formation. The occurrence of hemorrhage within an intraosseous lipoma is exceptional. The intralesion hematoma demonstrates intermediate signal intensity on T1W, and mixed high and low signal intensity on T2-weighted imaging, as reported by Kwak et al. [2]. The outer capsule and intralesional fibrovascular rim at the interface of various transitional zones demonstrates post gadolinium enhancement. The zonal differentiation within the tumor indicates that the process of involution extends from center to the periphery, and continues till
e59
the entire lipomatous tumor is transformed into a complex cystic structure. In summary, we present a very rare case of bilateral Milgram stage III intraosseous lipoma, showing varied patterns of involution. The unequivocal diagnosis of an incidentally discovered calcaneal intraosseous lipoma prevents the unnecessary workup, biopsy and treatment of affected patients. References [1] Barcelo M, Pathria MN, Abdul-Karim FW. Intraosseous lipoma: a clinicopathologic study of four cases. Arch Pathol Lab Med 1992;116:947–50 [Medline]. [2] Kwak H-S, Lee K-B, Lee S-Y, Han Y-M. MR findings of calcaneal intraosseous lipoma with hemorrhage. AJR 2005;185:1378–9. [3] Milgram JW. Intraosseous lipomas: a clinicopathologic study of 66 cases. Clin Orthop 1988;231:277–302.
Contents lists available at ScienceDirect
European Journal of Radiology Extra journal homepage: intl.elsevierhealth.com/journals/ejrex
Radiological evaluation of bilateral intraosseous calcaneal lipoma in various stages of involution Shahina Bano a,∗ , Sachchida Nand Yadav b,1 , Vikas Chaudhary c,2 , Vijay Kumar Jain d,3 a
Department of Radiodiagnosis, Govind Ballabh Pant Hospital and Maulana Azad Medical College, Room No: 603, New Resident Doctor’s Hostel, New Delhi 110002, India Department of Radiodiagnosis, Dr. Ram Manohar Lohia Hospital & PGIMER, 208-D, Curzon Road Apartment, Delhi 110001, India Department of Radiodiagnosis, Employees’ State Insurance Corporation (ESIC) Model Hospital, Gurgaon, Room No: 27, New Resident Block, Lady Hardinge Medical College, New Delhi 110001, India d Department of Orthopedics, Dr. Ram Manohar Lohia Hospital & PGIMER, New Delhi 110001, India b c
a r t i c l e
i n f o
Article history: Received 6 November 2010 Received in revised form 21 January 2011 Accepted 28 January 2011
Keywords: Bilateral involuted intraosseous calcaneal lipoma Conventional radiograph Computed tomography Magnetic resonance imaging
a b s t r a c t Bilateral intraosseous lipoma is an unusual diagnosis. Radiological appearance depends on the stage due to evolutionary changes within the tumor. This report describes the imaging features of pathologically proven bilateral intraosseous calcaneal lipoma, showing the complete spectrum of evolutionary change, in the form of intralesional cyst, hemorrhage, fat necrosis, dystrophic calcification and woven bone formation, occurring simultaneously in the same patient. © 2011 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Occurrence of lipoma in bilateral calcaneus is extremely rare. To our knowledge, four cases of bilateral calcaneal lipoma and only two case of lipoma with hemorrhage have been described in the literature [1,2]. However, the various patterns of evolutionary change (as seen in our case) in the form of intralesional cyst, hemorrhage, fat necrosis, dystrophic calcification and woven bone formation simultaneously, in the same patient have not been reported till date. 2. Case report A 46-year-old male, football player, presented with intermittent pain and tenderness in bilateral heels of 6 month’s duration, which increased on weight bearing or sports activity. There was no history of trauma.
∗ Corresponding author. Mobile: +91 9868244786. E-mail addresses: dr [email protected] (S. Bano), sn [email protected] (S.N. Yadav), dr [email protected] (V. Chaudhary), dr [email protected] (V.K. Jain). 1 Mobile: +91 9868874466. 2 Department of Radiodiagnosis, Employee’s State Insurance Corporation (ESIC) Model Hospital, Gurgaon, Haryana, India. Mobile: +91 9968338008. 3 Mobile: +91 9968277722. 1571-4675/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrex.2011.01.015
Conventional lateral radiographs of bilateral calcaneus showed sharply defined lytic lesions with sclerotic borders at the base of calcaneus neck (Fig. 1). Axial CT demonstrated peripheral zone of fat density, and central area of soft tissue density. Bilateral mild medullary expansion was noted without any cortical breach (Fig. 2). On T1- and T2-weighted MR images (Fig. 3A and B) both the lesions demonstrated peripheral fatty zone of high (on T1WI) and intermediate (on T2WI) signal intensity; with central area of mixed signal intensity (hematoma) in right calcaneum; and myxoid degeneration with cyst formation in left calcaneum (cyst within cyst appearance). In both the lesions, a low signal intensity rim (woven bone-fibrovascular tissue complex) was detected at the junction of peripheral and central zone, on T2*GRE images (Fig. 3C). STIR imaging suppressed the peripheral fat, but the central area replaced by cystic degeneration and the hemorrhage appeared hyperintense (Fig. 3D). On T1-weighted fat suppression post gadolinium image, the outer capsules and the interface between the outer fatty layer and the inner hematoma/fluid component demonstrated rim enhancement (Fig. 3E). On the basis of above imaging findings, the diagnosis of bilateral intraosseous calcaneal lipoma, showing hemorrhage in right calcaneus; and variable degree of cyst formation in left calcaneus, was made. Because of the benignancy and the virtually diagnostic appearance of the lesion radiographically, a bone biopsy was not performed. Due to large symptomatic lesions, the patient
e58
S. Bano et al. / European Journal of Radiology Extra 78 (2011) e57–e59
Fig. 1. Lateral X-ray bilateral calcaneus shows well defined radiolucent lesions (thin large arrow) at ward’s triangles, with central oval shaped area showing thin peripheral rim of increased density (thick small arrow).
subsequently underwent surgical curettage and bone grafting. Histopathological examination confirmed the radiological diagnosis. Post-op recovery was excellent. 3. Discussion Intraosseous lipoma primarily affects lower extremities especially femoral metaphysics and neck of calcaneus. A primary lesion of intraosseous lipoma consists of mature lipocytes and frequently involutes spontaneously through the processes of infarction, calcification, cyst formation, fat necrosis, myxoid degeneration and reactive bone formation. Since these involutional changes lead to characteristic radiological and histopathological features, Milgram subdivided these entities into three stages – Stage I: solid tumour of viable lipocytes. Stage II: mixed pattern of viable and necrotic lipocytes along with focal areas of dystrophic calcification. Stage III: near complete/completely necrotic fat, calcification, variable degrees of cyst formation, and reactive new bone formation. The progression from stage 1 to stage 3 is caused by ischemia and infarction within the lesion [3]. Cross-sectional imaging findings are highly suggestive and avoids a biopsy. On CT, an intraosseous lipoma is seen as a well-circumscribed lytic lesion of fat density, with heterogeneity
Fig. 2. Axial CT of bilateral calcaneus demonstrates low density lesions (single large arrow) showing negative Hounsfield unit consistent with fat density (right foot, −130 HU; left foot, −90 HU), and central area (star) of soft tissue density (right foot, +35 HU; left foot, +21 HU) with peripheral rim calcification (thick small arrow). Multiple thin intervening trabeculae (double large arrow) are seen within both the lesions.
Fig. 3. (A) Sagittal T1-weighted MR images show right calcaneus demonstrating peripheral rim of high signal corresponding to fat (large arrow), and intermediate signal intensity in central portion of lesion consistent with hemorrhage (small thick arrow), while the left calcaneus shows outer layer of hyperintense fat (large arrow), surrounding the middle zone intermediate signal intensity rim consistent with ongoing fat necrosis/myxoid degeneration (small thick arrow), and central low signal intensity nidus consistent with fluid (star). (B) Corresponding T2-weighted Sagittal MR images show right calcaneus hematoma with mixed high and low signal intensity (small thick arrow), while the lesion in left calcaneus demonstrated cyst within cyst appearance due to presence of hypointense rim of calcification (thin long arrow) between high signal intensity central fluid (star) and middle zone ongoing fat necrosis (small thick arrow). (C) Coronal T2* GRE images show circumferential rim of low signal intensity at the margin of bilateral central lesions, and at the periphery of mid-zone cystic area in left calcaneus suggests woven bony trabeculae/calcification (white arrow). (D) Corresponding coronal inversion recovery (STIR) image confirms the presence of fat due to suppression of outer rim (thin white arrow). The central fluid/fat necrosis (star/thick black arrow) and hematoma (thin black arrow) demonstrate high signal intensity. (E) Post-contrast fat suppression T1-weighted coronal images show rim enhancement of the fibrovascular tissue at the interface between the outer fatty layer and the inner hematoma/fluid component (thin black arrow). The capsule of bilateral lesions also shows subtle, thin peripheral rim enhancement (thin white arrow).
S. Bano et al. / European Journal of Radiology Extra 78 (2011) e57–e59
resulting from fat necrosis, hemorrhage and dystrophic calcification. MRI is an excellent method for demonstrating fatty tissue which appears high signal intensity on T1W and intermediate signal intensity on T2W fast spin echo sequences. The areas of intermediate signal intensity on T1-weighted and high signal intensity on T2-weighted sequences are suggestive of ongoing fat necrosis, later resulting in cyst formation. The occurrence of hemorrhage within an intraosseous lipoma is exceptional. The intralesion hematoma demonstrates intermediate signal intensity on T1W, and mixed high and low signal intensity on T2-weighted imaging, as reported by Kwak et al. [2]. The outer capsule and intralesional fibrovascular rim at the interface of various transitional zones demonstrates post gadolinium enhancement. The zonal differentiation within the tumor indicates that the process of involution extends from center to the periphery, and continues till
e59
the entire lipomatous tumor is transformed into a complex cystic structure. In summary, we present a very rare case of bilateral Milgram stage III intraosseous lipoma, showing varied patterns of involution. The unequivocal diagnosis of an incidentally discovered calcaneal intraosseous lipoma prevents the unnecessary workup, biopsy and treatment of affected patients. References [1] Barcelo M, Pathria MN, Abdul-Karim FW. Intraosseous lipoma: a clinicopathologic study of four cases. Arch Pathol Lab Med 1992;116:947–50 [Medline]. [2] Kwak H-S, Lee K-B, Lee S-Y, Han Y-M. MR findings of calcaneal intraosseous lipoma with hemorrhage. AJR 2005;185:1378–9. [3] Milgram JW. Intraosseous lipomas: a clinicopathologic study of 66 cases. Clin Orthop 1988;231:277–302.