# Osteosarcoma in a Teenage Athlete With a Swollen Knee Joint

## TL;DR

A 17-year-old athlete was diagnosed with osteosarcoma in his left tibia after experiencing knee pain and undergoing imaging tests.

## Contribution

This paper presents a clinical case of osteosarcoma in a teenage athlete, highlighting diagnostic and treatment processes.

## Key findings

- A lytic lesion in the proximal tibia was identified via radiograph and confirmed as osteosarcoma via CT scan.
- The patient was diagnosed with metastatic osteosarcoma and started on chemotherapy with good initial tolerance.
- The case emphasizes the importance of timely imaging and biopsy for accurate diagnosis and treatment planning.

## Abstract

Osteosarcoma is a malignant mesenchymal tumour. This primarily manifests in the formation of immature osteoid cells by tumour cells. Osteosarcoma is the most common primary bone tumour in children and adolescents. It tends to occur in the metaphysis of long shafts, shows osteoblastic differentiation, and produces malignant osteoid material. We present the case of a 17-year-old male who presented to our clinic who had left knee pain for a few days. An initial radiograph of the knee joint revealed a lytic lesion in the proximal tibia and further imaging was advised. During a follow-up visit, the patient had worsening pain and had a computerized tomography scan of the left knee, confirming osteosarcoma on the lateral side of the left tibia. He was referred to the orthopaedic department, where a biopsy was performed, to confirm the diagnosis of osteosarcoma. The patient was commenced on chemotherapy due to metastatic disease and has so far tolerated therapy well.