Surface osteosarcoma, also known as parosteal or juxta-cortical, is one that begins on the surface of the bone and grows externally. There is no lesion in the bone marrow and on its surface we have the tumor growth zone represented, therefore the most immature region. It has two histological representations: -a) low grade : there are practically no atypical mitoses and it resembles mature bone. Your diagnosis is confirmed by clinical and imaging.
Surface osteosarcoma
-b) high grade : presents the same clinical characteristics but with atypia and immature neoplasm polymorphism.
Its clinical manifestation is characterized by a slow evolution , affecting the third and fourth decade, occurring in the posterior and distal metaphyseal region of the femur, popliteal cavus, proximal humerus and distal radius.
Radiologically, it is characterized by a dense lesion, of tumoral bone neoformation, whose base is in continuity with the cortex of the affected bone. The surface may have a cartilaginous layer and represents the immature zone.
The main differential diagnosis is myositis ossificans (which presents immaturity in the center of the lesion and whose periphery is more mature, calcified).
The treatment of low-grade surface osteosarcoma consists of oncological resection of the lesion, which may be partial parieltal or segmental, and reconstruction with a bone graft or endoprosthesis.
High grade is treated like central osteosarcoma, that is, chemotherapy – surgery – chemotherapy.
Author: Prof. Dr. Pedro Péricles Ribeiro Baptista
Orthopedic Oncosurgery at the Dr. Arnaldo Vieira de Carvalho Cancer Institute
Office : Rua General Jardim, 846 – Cj 41 – Cep: 01223-010 Higienópolis São Paulo – SP
Phone: +55 11 3231-4638 Cell:+55 11 99863-5577 Email: drpprb@gmail.com