Musculoskeletal system
Case TypeClinical Cases
Authors
Carmen Trejo Gallego, Almudena García Gerónimo, Ana Blanco Barrio.
Patient43 years, female
A 43-year-old woman with right peritrochanteric pain. She had a history of non-treated dyslipidemia and no previous surgical interventions. She did not report a recent trauma or fall. Hip radiographs were assessed in another institution and given the non-specific findings, CT and MRI were performed for further investigation.
First, multidetector computed tomography (fig.1) revealed a lytic lesion in the intertrochanteric region of the right femur with well defined, geographic sclerotic margins. The lesion neither insufflated the cortical nor produced a periosteal reaction. It measured 4x3x2 cm and had no-fat attenuation values. It was hyperattenuated compared to muscle.
MRI showed a well-defined lesion, which was hypointense on T1 weighted images (WI) (fig.2) and hyperintense on GRE T2*. The lesion was surrounded by a hypointense rim on both pulse sequences, which was interpreted as an area of sclerosis. The STIR sequence demonstrated lack of homogeneous suppression of fat signal within the lesion.
These findings would suggest the differential of: liposclerosing myxofibroid tumor, enchondroma, xantoma of the bone, fibrous dysplasia and non-ossifying fibroma.
Radiology report suggested liposclerosing myxofibroid tumour and fibrous dysplasia as the most probable diagnosis, based on semiology and location of the lesion.
Our patient underwent curettage and prophylactic internal fixation [1-3]
Xanthoma of the bone (XOB) is a rare bone lesion that has been associated with metabolic diseases like hyperlipidemia, however, XOB can occur in patients with normal lipid profiles [3-7]. XOB appears in almost all ages but is infrequent in pediatric patients [6]. They occur in the appendicular or axial skeleton, including the pelvis and skull base [6].
Histological studies show cholesterol clefts, foamy histiocytes and inflammatory cells. Immunohistochemically, the xanthomatous cells are: CD 68 and vimentin-positive and negative for cytokeratine, AE1/AE3, S100, PAX 8 and CD1a.
Patients are usually asymptomatic but sometimes they can report pain.
Plain radiographs show subtle lucencies in the proximal metaphyseal to diaphyseal regions of the long bones. Perhaps the mechanism of the metaphyseal deposits is the slowing of regional blood flow in that region where the arteries form loops to drain into veins [8]. Most cases show partially or completely sclerotic margins. Intralesional calcification is absent, excluding enchondroma from the differential[9]. Sometimes XOB can exhibit an aggressive appearance, with an expansile border, lack of sclerotic rim, cortical disruption [2] and may mimic malignancy [3-5,10-12].
CT shows a loss of normal trabecular pattern in the medullary cavity. The lesion may have a mixed lytic and ground glass appearance [13] . The medullary cavity may have a density greater than normal bone marrow with or without cortical disruption[9,14] or endosteal reaction. The “soft tissue” density on the lesion may be due to a high percentage of cholesterol in hyperlipidemic patient’s xanthomas, containing relatively less triglyceride than the adipocytes in uninvolved bone marrow [14].
MRI is characterized by a circumscribed area of heterogeneous signal intensity on T1 and T2 WI (usually hypointense and hyperintense respectively), and a loss of signal when fat is suppressed, which is hypothesized to result from the cholesterol-laden histiocytes seen histopathologically. T2 WI can reveal the lesion to be surrounded by areas of low signal intensity, concordant with reactive bone sclerosis[9,12].
The nonspecific radiological appearance of the lesion and its low incidence makes it difficult to diagnose using only clinical and imaging techniques. The attenuation values let us exclude intraosseous lipoma from the differential diagnosis and the age of presentation make fibrous dysplasia and non-ossifying fibroma a less likely possibility. Histopathological and immunohistochemical staining is crucial to differentiate it from other entities involving histiocytes.
Written informed patient consent for publication has been obtained.
[1] Ahmed G, Al Dosari M, El-Mahi M, Abolfotouh SM. Primary xanthoma of calcaneus bone: Case report. Int J Surg Case Rep [Internet]. 2014;5(10):699–702. Available from: http://dx.doi.org/10.1016/j.ijscr.2014.07.016 (PMID: 25194608)
[2] Kovac A, Kuo YZ, Sagar V. Radiographic and radioisotope evaluation of intra osseous xanthoma. Br J Radiol. 1976;49(579):281–5. (PMID: 1276595)
[3] Alden KJ, McCarthy EF, Weber KL. Xanthoma of bone: a report of three cases and review of the literature. Iowa Orthop J. 2008;28:58–64. (PMID: 19223950)
[4] De Araujo MR, Scariot R, Uetanabaro L, Luvison Gomes Da Silva L, Giovanini AF. Primary mandibular xanthoma: Case report. Oral Surg Oral Med Oral Pathol Oral Radiol [Internet]. 2015;120(4):e177–82. Available from: http://dx.doi.org/10.1016/j.oooo.2015.01.015 (PMID: 25794795)
[5] de Arruda JAA, Almeida TFA, Abreu LG, do Amaral MBF, Anbinder AL, Flores RM, et al. Intraosseous xanthoma of the mandible: A multi-institutional case series with a literature review. J Oral Pathol Med. 2019;48(10):935–42. (PMID: 31355943)
[6] Wang Z, Lin ZW, Huang LL, Ke ZF, Luo CJ, Xie WL, et al. Primary non-hyperlipidemia xanthoma of bone: A case report with review of the literature. Int J Clin Exp Med. 2014;7(11):4503–8. (PMID: 25558299)
[7] Shin WC, Moon NH, Suh KT. Primary Intraosseus Xanthoma Involving the Proximal Femur in a Normolipidemic Patient: A Case Report. Hip Pelvis. 2016;28(3):182. (PMID: 27777923)
[8] Torigoe T, Terakado A, Suehara Y, Kurosawa H. Xanthoma of bone associated with lipoprotein lipase deficiency. Skeletal Radiol. 2008;37(12):1153–6. (PMID: 18828009)
[9] Yamamoto T, Kawamoto T, Marui T, Akisue T, Hitora T, Nagira K, et al. Multimodality imaging features of primary xanthoma of the calcaneus. Skeletal Radiol. 2003;32(6):367–70. (PMID: 12719924)
[10] Turk C, Bilginer B, Benli K, Yavuz K, Saglam A, Ziyal IM. Bilateral temporal bone xanthomas in type II hypercholesterolemia. Turk Neurosurg. 2010;20(4):533–5. (PMID: 20963706)
[11] Han Y, Gao W, Liang P, Wang S, Chen Y, Qiu J. Clinical features of bilateral temporal bone xanthoma with LDLR gene mutation. Int J Pediatr Otorhinolaryngol [Internet]. 2015;79(7):1148–51. Available from: http://dx.doi.org/10.1016/j.ijporl.2015.04.020 (PMID: 25921077)
[12] Ali S. Bilateral primary xanthoma of the humeri with pathologic fractures: A case report. World J Radiol. 2013;5(9):345. (PMID: 24198913)
[13] Broadway S, Arnautovic K, Zhang Y. Xanthoma of the Occipital Bone and With Preserved Inner and Outer Bone Cortex: Case Report. J Neurol Surg Reports. 2013;74(01):029–32. (PMID: 23943717)
[14] Fink IJ, Lee MA GR. Case reports malignant lesion. Br J Radiol. 1985;58:262–4. (PMID: 4063668)
URL: | https://www.eurorad.org/case/17204 |
DOI: | 10.35100/eurorad/case.17204 |
ISSN: | 1563-4086 |
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.