Ben Romdhane Majdi, Kedous Mohamed Ali, Rebhi Safouen, Chebbi Wael, Mbarek Mondher and Boujelbene Nadia
Chondroblastoma is a rare bone tumor of cartilaginous origin representing less than 1% of all the primitive bone tumors. This lesion usually develops in the epiphysis of long bones and occurs during the second decade of life. However, there are rare atypical localizations like the patella. We report an atypical case of chondroblastoma of the patella and discuss the clinical, radiological and therapeutic features of this rare location. A young 20-year-old patient consulted for right knee pain evolving for 2 months with a discreet knee effusion and pain on palpation of the patella. The radiological and CT showed lytic lesion of the distal half of the patella, lobulated, with sclerotic outlines and blowing the internal cortex. The patient underwent surgery with curettage and filling with autologous iliac cancellous bone graft. Histological examination led to the diagnosis of chondroblastoma. At last follow-up, 18 months, the patient had a normal function of his knee with no recurrence for radiological control. The location of chondroblastoma in the patella is exceptional but its radiological features resemble those of usual epiphyseal locations. The most popular treatment is curettage associated with cancellous bone grafting and thus to avoid the functional consequences of a patellectomy.