Case Study

Dedifferentiated chondrosarcoma: An aggressive variant of chondrosarcoma

Asian Cardiovascular & Thoracic Annals 2015, Vol. 23(2) 221–223 ß The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0218492314522253 aan.sagepub.com

Gangadhara Bharath1, Rajaram Burrah1, Kuppuswamy Shivakumar1, Suraj Manjunath1 and Rao Bhanumathi2

Abstract Dedifferentiated chondrosarcomas are a rare and aggressive subtype of chondrosarcoma with a bimorphic pattern on histopathology. Rib is a rare site of dedifferentiated chondrosarcoma. Diagnosis of this subtype preoperatively can be challenging. Treatment options for dedifferentiated chondrosarcoma are limited because they are chemoresistant, and therefore adequate surgery forms the main stay of treatment. We present our experience with a dedifferentiated chondrosarcoma of the rib, and discuss the management of this rare entity.

Keywords Bone neoplasms, chondrosarcoma, ribs

Introduction Dedifferentiated chondrosarcoma is a rare subtype of chondrosarcoma, associated with a poor prognosis. It differs from chondrosarcoma by containing a highgrade mesenchymal non-cartilaginous component in addition to the components of chondrosarcoma. It commonly affects the femur or pelvis, presents in an advanced stage, and affects mainly the elderly.1,2 Treatment of these neoplasms can be challenging because they do not behave like conventional chondrosarcomas. We present our experience with a dedifferentiated chondrosarcoma of the rib.

Case report A 60-year-old man presented with a swelling on his right chest wall for 10 years. He had noticed an increase in size with pain in the swelling in the previous month. Local examination showed a solitary 15  15-cm hard and immobile swelling over the anterolateral aspect of the 6th, 7th, and 8th ribs. Chest radiography (Figure 1) and computed tomography (Figure 2) showed a large irregular heterogeneously enhancing lesion with punctate calcifications, arising from the anterolateral aspect of the right 7th rib, with a large exophytic component. Taking into consideration the patient’s age, history,

examination and imaging findings, a working diagnosis of chondrosarcoma was considered. Core needle biopsy showed a neoplasm composed of large cells with hyperchromatic nuclei and a moderate amount of cytoplasm, arranged in a background of chondroid matrix. No mitotic figures were seen, and the microscopic features were consistent with grade 1 chondrosarcoma. The patient was scheduled for wide excision of the lesion and chest wall reconstruction. At surgery, the tumor was found to arise from the 7th rib with involvement of the 6th and 8th ribs. The tumor was adherent to the underlying lung and diaphragm. The lesion was resected with a margin of the 5th and 9th ribs, and the adherent lung and diaphragm were also included (Figure 3). The chest wall was reconstructed with PTFE mesh. Pathology (Figure 4) showed an infiltrating neoplasm composed of atypical chondrocytes in 1 Department of Surgical Oncology, St. John’s Medical College & Hospital, Bangalore, India 2 Department of Pathology, St. John’s Medical College & Hospital, Bangalore, India

Corresponding author: Rajaram Burrah, Department of Surgical Oncology, St. John’s Medical College & Hospital, Sarjapur Road, Bangalore, Karnataka 560034, India. Email: [email protected]

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Asian Cardiovascular & Thoracic Annals 23(2) sheets and lobules with moderate cellularity. The cells displayed mild nuclear pleomorphism and hyperchromatic nuclei. A chondroid matrix with areas of hyalinization was seen along with foci of calcification. Also seen were clearly demarcated areas composed of pleomorphic spindle cells with surrounding tumor osteoid. The histopathology was reported as grade 2 chondrosarcoma of the ribs with dedifferentiation into osteosarcoma, with free resection margins. In view of this report, the patient was offered chemotherapy but he refused it. He has been asymptomatic on follow-up, and imaging carried out at 8 months postoperatively did not reveal any metastatic disease.

Discussion

Figure 1. Chest radiograph showing a large heterogenous right lower chest wall lesion with punctate calcification.

Dedifferentiated chondrosarcoma, also known as spindle cell chondrosarcoma, is a rare and aggressive variant of chondrosarcoma. The clinical and pathological features were first described by Dahlin and Beabout1 in 1971. The incidence of dedifferentiated chondrosarcoma reported in the literature is 10%.3 It occurs more frequently in the elderly and in males.1 The commonly described sites are femur, pelvis, humerus, scapula and rarely, ribs. The diagnosis of dedifferentiated chondrosarcoma is usually obtained postoperatively,

Figure 2. Computed tomography showing a large heterogeneously enhancing lesion arising from the 7th rib, with punctate calcification and a large exophytic component.

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Figure 3. Intraoperative photograph showing the tumor adherent to the underlying lung (white arrow) and diaphragm (black arrow).

biopsy were suggestive of chondrosarcoma, and there was no evidence of metastasis elsewhere. Wide excision of the lesion and chest wall reconstruction were performed, and histopathology revealed a low-grade chondrosarcoma with dedifferentiation into osteosarcoma. The prognosis of patients with dedifferentiated chondrosarcoma is poor. The median survival is approximately 7.5 months with a 5-year disease-free survival of 7.1%.4 The role of adjuvant chemotherapy is undefined and may not help in improving survival or decreasing recurrence.4 Neoadjuvant chemotherapy has also been tried but has not produced a good response or improved survival.1,3,5 Our patient refused adjuvant therapy, but on follow-up at 8 months, he was disease-free. Chondrosarcoma is the most common chest wall tumor, and the dedifferentiated variant is a described subtype. Its varied composition makes dedifferentiated chondrosarcoma a challenge for diagnosis preoperatively. Suspected chondrosarcomas in the elderly, with a rapid increase in size and pain, should raise the suspicion of dedifferentiated chondrosarcoma. The overall prognosis is poor due to systemic dissemination, suggesting there may be a role for systemic therapy, but the results of adjuvant treatment have not been encouraging. Further studies are required to identify a systemic therapy to improve survival. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflicts of interest statement None declared.

References

Figure 4. Histopathology demonstrating an abrupt transition: on the left is low-grade chondrosarcoma (white arrow) and on the right is osteosarcoma (black arrow) characterized by malignant spindle cells with tumor osteoid. Hematoxylin and eosin stain, original magnification 100.

although there are radiological features that may diagnose it preoperatively.1 Our patient was an elderly male who presented with a right chest wall lesion. The imaging and core needle

1. Staals EL, Bacchini P and Bertoni F. Dedifferentiated central chondrosarcoma. Cancer 2006; 106: 2682–2691. 2. Lin JR, Zhang WM and Wang ZC. Primary malignant bone neoplasm: a case report of dedifferentiated chondrosarcoma in the rib and review of the literature. Chin J Cancer 2010; 29: 964–968. 3. Frassica FJ, Unni KK, Beabout JW and Sim FH. Dedifferentiated chondrosarcoma. A report of the clinicopathological features and treatment of seventy-eight cases. J Bone Joint Surg Am 1986; 68: 1197–1205. 4. Dickey ID, Rose PS, Fuchs B, Wold LE, Okuno SH, Sim FH and Scully SP. Dedifferentiated chondrosarcoma: the role of chemotherapy with updated outcomes. J Bone Joint Surg Am 2004; 86: 2412–2418. 5. Capanna R, Bertoni F, Bettelli G, et al. Dedifferentiated chondrosarcoma. J Bone Joint Surg Am 1988; 70: 60–69.

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Dedifferentiated chondrosarcoma: an aggressive variant of chondrosarcoma.

Dedifferentiated chondrosarcomas are a rare and aggressive subtype of chondrosarcoma with a bimorphic pattern on histopathology. Rib is a rare site of...
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