British Journal of Radiology (2007) 80, e268-e270
© 2007 British Institute of Radiology
doi: 10.1259/bjr/13711118
Primary retroperitoneal extraskeletal mesenchymal chondrosarcoma: a computed tomography diagnosis
K Taori, MD
P Patil, MBBS
V Attarde, MBBS
S Chandanshive, MBBS
V Rangankar, MD
and
N Rewatkar, MBBS
Department of Radiology, Government Medical College, Nagpur, India 440003
Correspondence: Dr Kishor Taori, MD, Professor and Head, Department of Radiology, Government Medical College, Nagpur, India 440003. E-mail: kishortaori{at}yahoo.co.in
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Abstract
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Mesenchymal chondrosarcomas, although very rare compared with conventional chondrosarcomas, are one of the few primary malignant tumours of bone that sometimes also arise in the soft tissues. Here we present a rare case of retroperitoneal extraskeletal mesenchymal chondrosarcoma (ESMC) in a 50-year-old female that showed characteristic extensive calcification. In this report, we discuss CT features of ESMC with pathological correlation.
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Introduction
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Chondrosarcoma is an uncommon malignant neoplasm of cartilaginous origin. Extraskeletal chondrosarcomas are far less common than their intraosseous counterparts, representing approximately 2% of all soft-tissue sarcomas. Mesenchymal chondrosarcoma is a rare and more aggressive variant of conventional chondrosarcoma, and constitutes approximately 1% of all chondrosarcomas [1]. However, approximately 30–50% of all mesenchymal chondrosarcomas are of extraskeletal origin. Men and women are affected equally, most frequently in the second to third decades of life [2].
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Case report
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A 50-year-old female presented with a large right-sided painless abdominal lump. Abdominal ultrasound abdomen was performed, revealing a huge, solid, heterogeneous retroperitoneal mass on the right side that was crossing the midline (Figure 1
). The tumour showed multiple scattered areas of increased echogenicity with dense posterior shadowing that suggested foci of calcification.
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Figure 1. 50-year-old female with retroperitoneal mass. Abdominal ultrasound showing solid, heterogeneous retroperitoneal mass with multiple scattered areas of increased echogenicity and dense posterior shadowing suggestive of foci of calcification.
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Topogram showed a large soft-tissue mass with extensive calcifications (Figure 2). CT of the abdomen and pelvis (Figure 3) revealed a large retroperitoneal soft-tissue density mass measuring approximately 20x12x18 cm in transverse, anteroposterior and craniocaudal axes, respectively. The tumour showed extensive ring- and arc-like calcific foci. The tumour was displacing the right kidney and ascending colon anteromedially towards the left side. The patient underwent total surgical resection of the mass. Histological examination revealed findings consistent with extraskeletal mesenchymal chondrosarcoma (ESMC) (Figure 4).
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Figure 2. 50-year-old female with retroperitoneal mass. Topogram showing a large soft-tissue mass with extensive calcifications.
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Figure 3. 50-year-old female with retroperitoneal mass. Contrast-enhanced CT of the abdomen and pelvis showing a large right-sided retroperitoneal soft-tissue density mass with extensive dense as well as arc-like calcific foci and mild heterogeneous contrast enhancement.
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Figure 4. 50-year-old female with retroperitoneal mass. Photomicrograph of a histopathological specimen showing abnormal neoplastic chondrocytes (original magnification x200; haematoxylin-eosin staining).
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Discussion
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Chondrosarcomas are a heterogeneous group of malignant tumours of cartilaginous origin. Although most chondrosarcomas arise from cartilaginous or bony structures, they may also develop in extraskeletal locations such as in soft tissues where cartilage is normally not found. It is unclear whether these tumours develop from mesenchymal differentiation or ectopic chondroid precursor cells. Extraskeletal soft-tissue chondrosarcomas are uncommon, accounting for less than 1% of all sarcomas [3]. The most common presentation is a mass; however, when in the abdomen or pelvis, these tumours can reach enormous sizes before detection, as in the case discussed.
Histological subtypes of extraskeletal chondrosarcoma include myxoid, mesenchymal and well-differentiated, with myxoid variety being the commonest [4]. Mesenchymal is a rare and more aggressive type, and has a poor prognosis. Histologically, it shows a characteristic bimorphic pattern, a combination of highly cellular undifferentiated mesenchymal cells and islands of well-differentiated cartilage. This highly malignant, cartilage-producing sarcoma was first described in bone by Lichtenstein and Bernstein in 1959 [5], and in soft tissue by Dowling in 1964 [6].
Compared with conventional chondrosarcomas (Table 1), mesenchymal chondrosarcomas commonly have an extraskeletal location, earlier age at presentation, high chances of recurrence or metastases, and poorer prognosis [2, 7]. This patient unusually presented at a more advanced age.
ESMC can occur from any location containing mesenchymal cells, but most arise in the lower extremities (particularly the thigh), leptomeninges, or in the orbit [2]. Other sites including the retroperitoneum are very uncommon. There have been reports of mesenchymal chondrosarcomas occurring in the heart, pleura and labia majora [8–10].
As retroperitoneal chondrosarcomas present as an abdominal mass, they are screened using ultrasound, which usually reveals a solid heterogeneous mass, often containing scattered areas of increased echogenicity and posterior shadowing due to calcific foci [11, 12].
Conventional radiography, CT and MR imaging of ESMC demonstrate several overlapping features with those of conventional chondrosarcoma. On radiography and CT, they appear as lobulated soft-tissue masses with calcifications. The typical appearance of the mineralized chondroid matrix is a ring- and arc-like pattern of calcification, which may coalesce to form a flocculent, fleck-like pattern. This characteristic chondroid calcification is the most useful and dominant feature of a cartilaginous lesion [13], hence the imaging diagnosis principally depends on CT. The delineation of the chondrosarcoma boundary relative to normal tissue can be achieved accurately when CT and MR imaging modalities are combined. Extensive calcification is more typical of extraskeletal mesenchymal chondrosarcoma than its skeletal counterpart and the myxoid variety [4, 14]. Amorphous and punctate calcification occurs more frequently in the myxoid variant. The mesenchymal variety has a lower water content compared with its myxoid counterpart due to the intermixture of small cells and more limited cartilaginous tissue, and, therefore, has attenuation similar to that of muscle on CT, typically having intermediate signal intensity on T2 weighted MR images [14]. Owing to the presence of high water content, myxoid-type chondrosarcomas show low attenuation on CT and high signal intensity on T2 weighted imaging.
Treatment most often involves radical surgical excision. The benefits from chemotherapy and/or radiotherapy are not yet clear. The prognosis is poor owing to the high likelihood of metastases, which often occur several years following initial treatment. Nakashima et al [2] reported a 5-year survival of 54% and a 10-year survival of 27%.
Although imaging features of ESMC are non-specific, younger age at presentation, and typical dense and arc-like calcifications may clinch the diagnosis of a tumour's extraskeletal origin. The pattern of calcification may help to differentiate it from other retroperitoneal sarcomas.
Received for publication May 8, 2006.
Revision received July 26, 2006.
Accepted for publication August 24, 2006.
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References
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Abstract
Introduction
