Table 1 Overview of the described intermediate types between osteosarcoma and osteoblastoma in human literature

Schajowicz and Lemos (1976) [15]

Malignant osteoblastoma

Mirra and others (1976) [16]

Pseudomalignant osteoblastoma

Revell and Scholtz (1979) [17]

Aggressive osteoblastoma

Dorfman and Weiss (1984) [18]

Subclassification in:

1. low-grade osteoblastoma-like osteosarcomas

2. pseudomalignant osteoblastoma

3. malignant transformation of initially benign osteoblastoma to a high-grade malignant osteosarcoma

4. locally aggressive/ malignant osteoblastoma

Bertoni and others (1985) [19]

Osteosarcoma resembling osteoblastoma

Bertoni and others (1993) [20]

Osteoblastoma-like osteosarcoma

Bertoni and others (1993) [21]

Osteoblastoma with cartilaginous matrix

De Oliveira and others (2007) [22]

Atypical osteoblastoma