A 12-year-old boy presented with pain and a mass on the medial aspect of the right proximal leg. He first noticed symptoms at around 10 years of age. The pain appeared on knee flexion, and was absent when he walked or ran. His height and body weight were 162 cm and 59 kg, respectively. He had no past medical history related to the lesion. There was no history of trauma or injury at the knee. On examination, a non-mobile hard mass was palpable with tenderness at the medical side of the proximal tibia. Swelling was not obvious. Plain radiographs showed a lesion protruding from the bone with continuity to the underlying bone. The size of the lesion was 0.8 cm on a plain radiograph (Fig. ). CT depicted a protuberant bone lesion with continuity to normal bone (Fig. ), but an overlying cartilaginous cap was not obvious. The MRI showed the lesion had continuity to the host bone marrow. There was no obvious inflammation characterized by high signal intensity on a T2 weighted fat-suppression image around the tip of the osteochondroma (Fig. ). For surgical resection, the lesions were approached posterior to the conjoint tendon (Fig. ). While retracting the attachment of the pes anserinus, the lesion was resected using a curved chisel. Histologically, the specimen showed partially sclerotic lamellar bone trabeculae covered by an attenuated hyaline cartilaginous cap undergoing endochondral ossification with fatty marrow, compatible with osteochondroma. There was no evidence of malignancy. Six months after surgery, the symptoms disappeared.
The third child was a 12-year-old male presenting to the outpatient department with complaints of swelling located in the medial aspect of right knee for the last three months. The swelling was insidious in onset without any history of trauma or fever. It was of the size of a lemon, as described by the patient’s guardian. There was associated vague pain in the same area, without any aggravating factor. There was no history of rapid increase in the size of swelling or the intensity of pain. Similar to the other two cases, there was no other swelling or pain elsewhere in the body. On examination, it was found that there was a bony hard, spherical, nodular, tender swelling on the medial aspect of right proximal tibia measuring 3 x 3 cm in size. The overlying skin was normal. Range of motion of knee joint was comparable to the other side. Plain radiograph of the right knee showed the presence of a bony outgrowth from the medial aspect of right proximal tibial metaphysis suggestive of an osteochondroma (Figure ). There was no evidence of malignant transformation on the plain radiograph. The patient was advised rest from exertional activities along with analgesic medications for three weeks causing reduction in pain. However, soon the pain started again gradually over a few days, for which the patient was injected with injection hydrocortisone and 2% xylocaine at the most tender point in the pes anserinus area. After this intervention, the patient became pain-free. The patient was regularly followed-up to check malignant transformation of the swelling. At the last follow-up of one-and-a-half years, there was no increase in the size of swelling or recurrence of pain.