Spontaneous Conventional Osteosarcoma Transformation of a Chondroblastoma: A Case Report and Literature Review

Abstract

Chondroblastomas are a primary benign cartilaginous tumor that accounts for approximately 1% of all benign bone tumors. Primarily they are treated by curettage. The patient presented 4 years after a successfully treated chondroblastoma (curettage and Bone cement). Wide resection of the proximal tibia with endoprosthesis replacement was done. Lung CT showed multiple lung metastasis and despite starting chemotherapy, he succumbed to the disease. We discuss regarding the possibilities of “aggressive” chondroblastoma and more recently termed chondroblastoma-like osteosarcoma which is a separate entity from chondroblastoma. Aggressiveness in chondroblastoma can be 1 of 3 types as follows: 1. benign chondroblastoma with lung metastasis. 2. malignant chondroblastoma. 3. subsequent malignant transformation of benign chondroblastoma. We have attempted to review the literature and describe the “aggressive” chondroblastoma and chondroblastoma-like osteosarcoma in this report.

Chondroblastoma of the Femoral Head: A Case Series and Literature Review

“…32 Although chondroblastomas are predominately benign, there have been rare cases of malignant transformation and metastasis to the lungs reported in the literature. 14,15,33 Therefore, their aggressive nature and propensity to manifest in a sometimes unpredictable manner, makes it vital to eliminate any delay in the diagnosis and subsequent treatment of these tumors.…”

Premalignant Conditions of Bone

“… 77 Other malignancies have been found in the setting of chondroblastoma as well, including osteosarcoma and malignant fibrous histiocytoma. 82 , 83 Nearly all malignant chondroblastomas occur in patients who have had a previous resection that later develops recurrence of their lesions. 77 , 82 , 83 Prognosis of malignant chondroblastoma is difficult to assess because it is rare and not fully understood; however, metastatic lesions in the setting of benign chondroblastoma portend a poor prognostic implication.…”

Identification of a novel iron zinc finger protein 36 (ZFP36) for predicting the overall survival of osteosarcoma based on the Gene Expression Omnibus (GEO) database

“…Osteosarcoma is a highly malignant primary tumor that originates from malignant mesenchymal cells (1), which has the characteristics of extensive tissue heterogeneity, high local invasiveness, rapid invasion and metastasis, and is more common in teenagers and children under 20 years old (2,3). The mortality rate of osteosarcoma is very high (4).…”