# Brown Tumor as a Reversible Cause of Osteolytic Lesions in Post-trauma Knee Pain: Role of Timely and Serial Parathyroid Hormone Testing

## TL;DR

A case study shows brown tumor, a rare bone condition, can mimic cancer and be diagnosed through PTH testing.

## Contribution

Highlights brown tumor as a reversible cause of osteolytic lesions and the importance of serial PTH testing for diagnosis.

## Key findings

- Brown tumor can present as lytic bone lesions similar to metastatic disease.
- Serial parathyroid hormone testing is crucial for diagnosing brown tumors in middle-aged patients.

## Abstract

Osteitis fibrosa is a metabolic skeletal disorder characterized by increased osteoblast and osteoclast activity, leading to abnormal bone matrix formation secondary to elevated parathyroid hormone (PTH) levels. Brown tumor is a rare and late manifestation of this condition that presents with focal well-defined osteolytic lesions, similar to metastatic disease. We present a case of a 52-year-old male with right knee pain following trauma. X-ray imaging demonstrated lytic lesions and a pathological fracture, ultimately leading to a diagnosis of a brown tumor. This case emphasizes the need to include brown tumors in the differential diagnosis of lytic bone lesions in middle-aged patients and highlights the role of serial PTH testing in identifying this uncommon condition.