Current Orthopaedic Practice:
Ossifying chondrolipoma of the thigh: radiographic pathologic correlation
Tomonaga, Masato; Kudawara, Ikuo
Osaka National Hospital, Osaka, Japan
Financial Disclosure: The authors report no financial conflicts of interest.
Correspondence to Ikuo Kudawara, MD, Department of Orthopaedic Surgery, 2-1-14 Hoenzka, Chuo-ku, Osaka 540-0006, Japan Tel: 81-6-6942-1331; fax: 81-6-6943-6467; e-mail: firstname.lastname@example.org
Lipomas are the most common benign soft-tissue tumors occurring in the subcutis or muscular regions. Histologically, lipoma consists of mature adipose cells, similar to normal adipose cells. Lipomas can occasionally have areas of bone or cartilage formation and are classified as osteolipomas or chondrolipomas, respectively.1,2 However, there have been few reported cases of lipoma with both ossification and cartilage formation.3,4 Here, we report an extremely rare case of ossifying intramuscular chondrolipoma in the thigh and review its radiographic and pathologic correlation. According to the guidance of the local institutional review board, the patient and her guardian provided informed written consent.
A 58-year-old woman presented with a painless mass in the left thigh of 3 yr’ duration. There was no history of trauma. On physical examination, a firm mass, 3×4 cm in size, was palpated on the anterior thigh. A lateral plain radiograph showed irregular mineralization in the soft tissue (Figure 1). Axial MRI demonstrated that the tumor, located within the rectus femoris muscle, had predominantly high-signal intensity on both T1-weighted and T2-weighted images. The medial border was poorly defined (Figure 2). Enhancement after Gd-DTPA administration was not seen. Sagittal MRI demonstrated the tumor, with irregular intermediate-signal intensity within the high-signal intensity area on the T1-weighted image (Figure 3A). On the T2-weighted image, the lesion had inhomogeneous high-signal intensity and partial intermediate-signal intensity (Figure 3B).
The tumor was completely removed under general anesthesia. The axial cut surface of the tumor was predominantly yellowish and partially glistening white (Figure 4). Each lesion was measured on the maximal cut surface: the lipomatous area was 56×21 mm in size, and the cartilaginous area was 35×20 mm. Histologically, the tumor was composed of mature adipocyte-like cells (lipoma cells) in the peripheral area, with ossification in the cartilaginous matrix in the central area (Figure 5). The cartilaginous cells were similar to hyaline cartilage cells and did not have nuclear atypism. From these findings, definitive diagnosis was ossifying chondrolipoma. There was no recurrence at 8 yr after surgery.
Lipomas occasionally can have other mesenchymal components, such as bone, cartilage, and vessels, and are classified as osteolipoma, chondrolipoma, and angiolipoma, respectively.1,2 Histologically, these are metaplasias from lipoma and not neoplastic changes.1,2 According to previous case reports, chondrolipomas and osteolipomas arise mostly from the breast5,6 or from the oral, nasopharyngeal, or pharyngeal regions.7–10 The occurrence in extremities is extremely rare: only five case reports of chondrolipoma are available.3,11–14
Radiographic features of conventional lipoma are well known.15 However, there have been few radiographic reports on the above subtypes of lipomas.15 Furtheremore, there is limited information available on the radiographic findings of chondrolipomas.3,4,13 Characteristic features of the MRI findings in our patient were the central area of tumor, intermediate signal intensity on T1-weighted images, and hererogeneous high-intensity on T2-weighted images, differing from adipose tissue. The heterogeneous signal intensity was similar to that in previously reported cases.3,13,14 The nonlipomatous lesion proved to be a cartilaginous area with ossification, as assessed by macroscopic and pathologic examinations. Usually, T2-weighted images of benign chondromatous lesions, such as soft-tissue chondromas or enchondromas, consist of lobulated bright signal intensity with partial low intensity, reflecting variable calcification.16,17 However, these typical findings were not seen in our patient. Another differential diagnosis is hemangioma, which often includes adipose tissue and occasional mineralization with poorly defined margins. Our radiographic findings mimicked this; however, central ossification in the tumor by radiograph ruled out phlebolith in hemangioma.
The gross appearance of the excised tumor consisted of a cartilaginous area with ossification in the lipomatous area (Figure 5). Histologically, the cartilaginous area contained mature chondrocytes and matrix, differing from chondroid lipoma.
Despite seeing central ossification in the cartilage component of the tumor, we could not establish whether the ossification developed from enchondral ossification in the cartilaginous area or from differentiation of lipomatous tissue. Cartilaginous tumors, such as synovial chondromatosis, enchondromas, soft-tissue chondromas, occasionally occur with ossification in chondroid matrix. On the other hand, they can arise from two different metaplasias such as ossification together with cartilage formation from lipoma. Recently, multipotent adult stem cells, the adipose-derived stem cells (ASCs), obtained from liposuction waste have the potential for chondrogenesis, osteogenesis, and myogenesis.18,19 Lipoma cells might have the potential to differentiate into other mesenchymal tissues. In our patient, the ossification area was focal and central surrounding the cartilage area. Moreover, the ossification pattern was similar to that in soft-tissue chondroma.20 Thus, we believe that ossification in chondrolipoma by enchondral ossification occurred over a long period of time. We finally diagnosed this from radiographs and pathological examinations as an ossifying chondrolipoma, not osteochondrolipoma.
In summary, we present a case of ossifying chondrolipoma of the thigh with radiographic and pathologic findings.
1. Nielsen GP, Mandahl N. Fletcher CDM, Unni KK, Mertens F. Lipoma. World Health Organization Classification. Tumours and Soft Tissue and Bone. 2002 .Lyon:IARC Press; 20–22.
2. Sharon WW, Goldblum JR. Sharon WW, Goldblum JR. Benign lipomatous tumors. Soft Tissue Tumors. 2008; :5th ed.Philadelphia:Mosby; 429–476.
3. Orui H, Ishikawa A, Tsuchiya T, et al. Chondro-osseus differentiation in fat tissue tumors:magnetic resonance imaging with pathological correlation. Skeletal Radiol. 2000; 29:459–465.
4. Hwang HS, Lee WJ, Lim HK, et al. Chondrolipoma in the pelvic cavity: a case report. Korean J Radiol. 2008; 9:563–567.
5. Greer J, Marjani M, Lowell D. Chondrolipoma of the breast:case report and review of the literature. Conn Med. 1999; 63:327–329.
6. Banev SG, Filipovski VA. Chondrolipoma of the breast-case report and a review of literature. The Breast. 2006; 15:424–425.
7. Nwaorgu OG, Akang EE, Ahmad BM, et al. Pharyngeal lipoma with cartilaginous metaplasis(chondrolipoma): a case report and literature rewiew. J Laryngol Otol. 1997; 111:656–658.
8. Kinshuck AJ, Agrawal S, Patel VM, et al. Nasopharyngeal chondrolipoma. Int J Otolaryngol. 2010; 2010:838046
9. Durmaz A, Tosun F, Kurt B, et al. Osteolipoma of the nasopharynx. J Craniofac Surg. 2007; 18:1176–1179.
10. Saghafi S, Mellati E, Sohrabi M, et al. Osteolipoma of the oral and pharyngeal region:report of a case and review of the literature. Oral Surgery, Oral Medicine, Oral Pathology, and Endodontology. 2008; 105:30–34.
11. Boltze C, Hribaschek A, Lippert H, et al. Intermuscular chondrolipoma of the thigh:the diagnostic way of a rare entity. Pathol Res Pract. 2003; 199:503–507.
12. Kruger S, Kisse B, Stahlenbrecher A, et al. Chondrolipoma of the hand: case report. Acta Orthop Belg. 2004; 70:495–497.
13. Candocia FJ, Barlev DM. Chondrolipoma in the palm of a child:sonographic and MR findings. Clinical Imaging. 2004; 28:206–208.
14. Ito R, Fujiwara M, Takagaki K, et al. Chondrolipoma of the toe. J Dermatology. 2007; 34:570–572.
15. Gaskin CM, Helmes CA. Lipomas, lipoma variants, and well-differentiated liposarcomas (atypical lipomas):results of MRI evaluations of 126 consecutive fatty masses. AJR Am J Roentgenol. 2004; 182:733–739.
16. Meyers SP. Meyers SP. Lesions that contain cartilage. MRI of Bone and Soft Tissue Tumors and Tumor Like Lesions. 2008 .Stuttgat New York:Thieme; 236–246.
17. Meyers SP. Meyers SP. Chondroma, intramedullary type:enchondroma (also referred to as intraosseus chondroma or central chondroma). MRI of Bone and Soft Tissue Tumors and Tumor Like Lesions. 2008 .Stuttgat New York:Thieme; 352–358.
18. Gimble JM, Guilak F. Adipose-derived adult stem cells: isolation, characterization, and differentiation potential. Cytotherapy. 2003; 5:362–369.
19. Zuk PA, Zhu M, Mizuno H, et al. Multilineage cells from human adipose tissue: implications for cell-based therapies. Tissue Eng. 2001; 7:211–228.
20. Fanburg-Smith JC, Murphey MD. Miettinen M. Cartilage- and bone-forming tumors and tumor-like lesions. Modern Soft Tissue Pathology. Tumors and Non-neoplastic Conditions. 2010 .New York:Cambridge University Press; 862–895.
This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License, where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially. http://creativecommons.org/licenses/by-nc-nd/3.0
© 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins