Myxoid Chondrosarcoma in the Calcaneus: a Case Report with MR

Skeletal Radiol (2007) 36: S82–S85 DOI 10.1007/s00256-006-0199-9 CASE REPORT

Jong Won Kwon Myxoid chondrosarcoma in the calcaneus: Jung-Ah Choi Kyu-Sung Kwack a case report with MR imaging findings Joo Han Oh Jin Haeng Chung Heung Sik Kang

Keywords Bone neoplasms . Received: 23 March 2006 J. H. Oh . Revised: 16 June 2006 Department of Orthopedic Surgery, Diagnosis MR Accepted: 2 August 2006 Seoul National University Published online: 12 January 2007 Bundang Hospital, # ISS 2007 Seong Nam, Gyeongi-Do, South Korea

J. H. Chung Department of Pathology, J. W. Kwon . J.-A. Choi (*) . Seoul National University K.-S. Kwack . H. S. Kang Bundang Hospital, Department of Radiology, Seoul Seong Nam, Gyeongi-Do, South Korea National University Bundang Hospital, 300 Gumidong, Bundang-Gu, Seong Nam, Gyeongi-Do, 463-707, South Korea Abstract Skeletal myxoid chondro- e-mail: [email protected] Tel.: +82-31-7877609 sarcoma is an extraordinarily rare Fax: +82-31-7874011 neoplasm with a distinct histological morphology. Herein, we report a case J.-A. Choi . H. S. Kang of a myxoid chondrosarcoma in the Department of Radiology, Seoul National University calcaneus of a 20-year-old man with a College of Medicine, description of its MR imaging (MRI) Seoul, South Korea and histological findings.

Introduction calcaneus, which is an unusual location for this tumor, with an emphasis on its radiological features, especially those that Myxoid chondrosarcoma of the bone is very rare. There are differentiate it from conventional chondrosarcoma. only a few references to this tumor in the literature. The most common location for skeletal myxoid chondrosarcoma is the femur [1]. Chondrosarcoma in the foot is Case report uncommon, and myxoid chondrosarcoma of the calcaneus is even rarer. Indeed, chondrosarcoma of any type is A 20-year-old male was admitted to the department of extremely rare in a 20-year-old adult. orthopedic surgery with a 6-month history of intermittent To our knowledge, this case is the third case of myxoid pain localized to the right heel. He had no history of chondrosarcoma in the calcaneus ever reported. The purpose trauma. There was neither tenderness on the right heel nor of this article is to report myxoid chondrosarcoma of the limitation of motion. S83

On the lateral plain radiograph of the right foot, there was a well-defined osteolytic mass in the calcaneus (Fig. 1). The tumor was lobulated and demarcated by a thin margin of sclerosis. On MRI (1.5-T MR scanner; Gyroscan NT Intera, Philips Medical Systems, Best, The Netherlands), the mass was seen as a well-defined lobulated mass of about 3.1×2.5×3.3-cm size with intermediate signal intensity similar to that of subcutaneous fat on T2-weighted images (WI) (Fig. 2), and as a low- signal-intensity septation in the mass with a sclerotic margin. There was a homogeneous low-signal-intensity mass on T1WI (Fig. 3). The contrast-enhanced T1- weighted axial image showed diffuse enhancement of the mass except for the amorphous central portion (Fig. 4). Considering the MR imaging findings, which suggested a benign tumor with a myxoid component and fibrous septae in the foot of a young adult, the initial radiological diagnosis was chondromyxoid fibroma. Percutaneous needle biopsy was performed. The pathologic diagnosis for the biopsy specimen was a spindle-cell proliferative lesion with myxoid stroma. The initial diagnosis based on the biopsy specimen was consistent with the Fig. 2 T2-weighted sagittal MR image (2,724/80/2 TR/TE/excita- tions). The mass shows slightly high signal intensity (arrow) similar radiological diagnosis of chondromyxoid fibroma. Because to that of subcutaneous fat and internal septation of the provisional radiologic and cytologic diagnosis of a benign bone tumor, simple curettage was done. The frozen specimen showed high cellularity and abnormal cells, and atypia and a high mitotic count (>6/50 high power field) the pathologic diagnosis for the frozen specimen was (Fig. 5). Even though the curettage specimen was chondrosarcoma. Anhydrous alcohol cauterization (using fragmented, tumor cells were observed to infiltrate the 240 cc for 10 min) and cement packing were performed. medullary spaces between bony trabeculae. Immunohisto- Microscopically, the lesion was composed of epithelioid chemical studies revealed positivity for S-100 protein. cellular nests in the chondromyxoid matrix with cytologic Tumor cells were negative for cytokeratin, p53, and CD34.

Fig. 1 Lateral radiograph of the right foot shows a well-defined osteolytic lesion in the calcaneus. There is a thin margin of sclerosis Fig. 3 T1-weighted sagittal image (456/20/2) shows a homogene- (arrow) ous low-signal-intensity mass with septation S84

Bone.” The tumors arose from the foot bones in three cases (the talus, calcaneus, and metatarsal) and the middle phalanx of the finger in one case. The authors designated these tumors as “solitary chondroblastic sarcomas.” The second case in the calcaneus was reported in 1984 [3]. In the second case, the tumor destroyed the cortex and extended to the sole of the foot and eventually recurred. Skeletal myxoid chondrosarcoma has been reported to present as a well-defined osteolytic lesion with endosteal scalloping, cortical invasion and expansion on radiographic examination [1]. But our case did not show cortical invasion or expansion, i.e., it had a benign appearance on radiography. More aggressive radiographic features have been reported including a permeative pattern of osseous destruction and an associated soft-tissue mass [1]. Unlike conventional chondrosarcoma, myxoid chondrosarcoma frequently contains hemorrhage, which appears as areas of high signal intensity on all MR pulse sequences, particularly in the large associated soft-tissue components. Our case did not contain hemorrhage or invade soft tissue. Contrast-enhanced images may show rings and arcs, which reflect the typical lobulated growth pattern of cartilaginous tumors of bone [4]. Initial preoperative radiologic diagnosis of our case was chondromyxoid fibroma based on the MR imaging findings, which suggested a benign lesion with a myxoid component and fibrous septation. Also, the young age of the patient led to a more benign impression of the lesion. It is cited that skeletal myxoid chondrosarcoma is distin- guished from chondromyxoid fibroma mainly by the sharply demarcated radiographic area of bone destruction and histologically by the lack of stellate and spindle cells randomly arranged within the fibromyxoid stroma and accompanied by multinucleated giant cells [5]. However,

Fig. 4 Gadolinium-enhanced T1-weighted axial image shows diffuse enhancement of the mass except for the amorphous central portion. There is endosteal scalloping at the medial aspect of the calcaneus (white arrow)

The final pathologic diagnosis was intraosseous myxoid chondrosarcoma.

Discussion

Skeletal myxoid chondrosarcoma is a rare histologic variant of chondrosarcoma that is considered an intermediate-grade tumor. In 1959, Lichtenstein and Bernstein [2] Fig. 5 The photomicrograph (×200, hematoxylin-eosin stain) reveals a cartilage neoplasm with prominent myxoid changes and described four neoplasms that may have represented a cord-like arrangement of cells. The cytoplasm appears vacuolated, skeletal myxoid chondrosarcoma in their article entitled and clear spaces are seen in the matrix surrounding several of the “Unusual Benign and Malignant Chondroid Tumors of cells, suggesting cartilage S85 our case showed no area of bone destruction, rendering the calcification or ossification of the matrix, which is differential diagnosis difficult. frequently observed in conventional chondrosarcoma; it Microscopically, skeletal myxoid chondrosarcoma is is usually a less aggressive neoplasm than conventional composed almost entirely of a myxoid matrix, with only chondrosarcoma [9]. However, the lesion may recur locally minimal hyaline cartilage formation [6]. This tumor has and occasionally may metastasize or pursue an aggressive markedly high water content, related to the extensive course [10]. myxoid stroma and better-differentiated areas of hyaline The immunoprofile of skeletal myxoid chondrosarcoma cartilage. The conventional osseous chondrosarcoma with is positive for S-100 protein, but negative for epithelial myxoid alteration appears microscopically to have neo- markers [1]. Although cases of myxoid chondrosarcoma plastic cells set in distinct lacunar spaces, suggestive of lacking S-100 immunopositivity have been reported in the hyaline cartilage formation. On the other hand, the skeletal literature [11], detection of this protein in tumor cells is a myxoid chondrosarcoma was described to be distinct from means of distinguishing between myxoid chondrosarcoma the usual chondrosarcoma of the bone, most probably and other malignant myxoid tumors, such as the myxoid representing the skeletal counterpart of extraskeletal myx- type of malignant fibrous histiocytoma. Our case showed a oid chondrosarcoma [1]. In some references, skeletal and positive result as well. extraskeletal myxoid chondrosarcoma are described to be Although only limited conclusions can be drawn from morphologically identical, and imaging studies are neces- the small sample of reported cases, affected individuals are sary to confirm the bone or soft tissue origin of the tumor typically male adults, and half of the reported cases have [7]. In another study, skeletal myxoid chondrosarcoma is occurred in the femur [8]. Based on this small sample, it said to be morphologically distinct from the extraskeletal also appears that myxoid chondrosarcoma of the bone has a counterpart by virtue of the lobulated, multinodular more aggressive clinical course than conventional intra- appearance, comprised of a uniform population of rounded medullary chondrosarcoma, with patients commonly to slightly spindled cells. The neoplastic cells with developing distant metastases and local recurrence [8]. hyperchromatic nuclei and inconspicuous nucleoli are This aggressive behavior contrasts sharply with that of described to be arranged in anastomosing chords, strands, low-grade conventional chondrosarcoma, which rarely and nests and pseudopapillary structures embedded in an metastasizes in the absence of dedifferentiation [12]. abundant, mostly hypovascular, mucinous matrix [8]. In conclusion, we report a rare case of a skeletal myxoid Myxoid chondrosarcoma can be differentiated from chondrosarcoma, with the imaging findings correlating conventional chondrosarcoma by the following aspects: it well with the histological features and distinct from lacks the well-differentiated features of cartilage, such as conventional chondrosarcoma, yet different from pre- lacunar formation around the chondroblasts; it also lacks viously reported imaging findings.

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