LOW-GRADE INTRAMEDULLARY OSTEOSARCOMA - A STUDY OF 8 CASES

Purpose of the study The authors reviewed eight patients treated for L ow Grade Intramedullary Osteosarcoma (LGIO). They analyzed the radiogr aphical and histological features and evaluated the prognosis of this disease. Materials Eight cases of LGIO were studied,The mean follow-up period was 3.9 years. LGIO is defined as a Broders classification gra de I osteosarcoma. The study involved 3 males and 5 females. Mean age at the time of diagnosis was 28. Methods Clinical records, radiographs and C.T. Scan were available and reviewed in all cases. Five patients had had MRI. In addition to the conventionnal histological study, ult rastructural studies were conducted in three of the cases. On their la st examination, all patients received a clinical and X-ray assessment. Results The tumor was localized around the knee in six cases on the h umerus and on the proximal femur in one case. The tumor was situated i n the metaphysis and was most often lytic. A malignant tumor was suspe cted at the outset for only two of the patients. The scanner and the M RI revealed a cortical discontinuity and extraosseous involvement in f ive cases. Seven patients had a wide resection, which was intra-tumora l once. The histological examination of two of those resections reveal ed limited areas of anaplasia; complementary chemotheray was then cond ucted, We did not observe any local recurrence in this group, We obser ved, however, an iliac metastasis, for which another wide resection wa s performed. This last patient remained free of disease three years la ter. One patient had radiotherapy and chemotherapy; he died from pulmo nary metastasis after his LGIO turned into high grade osteosarcoma. Di scussion LGIO are rare, they represent 1,8 per cent of all Osteosarcom as in the Cochin file. The mean age of patients contracting LGIO is hi gher than that of conventional osteosarcoma patients. Observation of t he radiographs and histological examination could lead to think the tu mor is begnin, and mistake it with a fibrous displasia, The C.T. Scan and the MRI have the advantage of showing soft tissue invasion and hel p the histological examination. The wide resection is the only treatme nt able to cure the patient, Chemotherapy would be useful for LGIO cas es containing limited areas of anaplasia. Conclusion LGIO is a slowly- evolving tumor, It remains localized for a long period of time. The hi stological diagnosis is difficult and requires a pathologist familiar with bone tumors. Its treatment requires surgery. LGIO must be disting uished from conventional osteosarcomas because of its better prognosis .