Hoffa Osteochondroma - Para-articular Extrasynovial Infrapatellar Fat Pad Osteochondroma: A Case Report

Osteochondroma usually arises from the metaphyseal region of growing bones. The occurrence of extraskeletal osteochondroma is rare with very few case reports. Para-articular osteochondroma is a type of extraskeletal osteochondroma. It frequently occurs around the knee, usually at infrapatellar Hoffa's fat pad. It is usually intracapsular but extrasynovial and arises from the capsule and connective tissues due to osteocartilaginous metaplasia. We present a case of 19-years male with anterior knee pain for 3 years, swelling, and deformity of the knee with flexion limitation for one year. Radiography revealed ovoid, corticated lesion free from adjoining bones. Mass interpreted as benign, so planned for excision. Well circumscribed nodule excised from the medial parapatellar approach. Histology revealed cartilaginous tissues surrounded by fibrous tissues with scattered enchondral ossification. Postoperatively and subsequent follow-up resulted in pain-free joint, complete recovery of range of motion with no clinicoradiological evidence of recurrence.