# Unusual Presentation of Synovial Lipomatosis Mimicking As Septic Arthritis of Knee: A Case Report

## TL;DR

A rare case of synovial lipomatosis in the knee was initially mistaken for septic arthritis due to similar symptoms.

## Contribution

This case report highlights the unusual presentation of synovial lipomatosis mimicking septic arthritis.

## Key findings

- The patient's symptoms resembled septic arthritis but were later diagnosed as synovial lipomatosis.
- Intraoperative and histopathological assessments confirmed the presence of synovial lipomatosis.

## Abstract

Synovial lipomatosis or lipoma arborescens is a very uncommon pseudo-tumorous lesion of the synovium which more commonly affects the knee joint. The most probable cause of this pathological lesion is degenerative articular disorders of the joint and improper fat accumulation. It is characterized by presence of villous proliferation of the synovium and replacement of the sub-synovial tissue by mature adipocytes which is infiltrated by dense chronic inflammatory cells like lymphocytes, plasma cells and eosinophils. This condition is rarely seen in smaller joints. Its aetiology is still unknown. We report a patient who presented with features of septic arthritis which on intraoperative and histopathological assessment showed features of synovial lipomatosis.