# Insidious Synovial Sarcoma of Bone in a Patient with Rheumatoid Arthritis

## TL;DR

A rare bone tumor was misdiagnosed as rheumatoid arthritis, leading to a fatal outcome due to delayed detection and complications.

## Contribution

Highlights diagnostic challenges of synovial sarcoma when it originates in bone and lacks palpable mass.

## Key findings

- Synovial sarcoma can present as hip pain without a palpable mass, leading to misdiagnosis.
- Delayed diagnosis due to symptom overlap with rheumatoid arthritis can result in fatal outcomes.
- Small or deep tumors are particularly challenging to detect and diagnose.

## Abstract

Synovial sarcoma is a rare malignity of mesenchymal origin; the diagnostic approach usually begins by documenting a soft tissue tumor; however, it results in a challenging diagnosis when it is more profound, of small size, or primary from the bone.

The present report describes a patient who presented insidious onset hip pain attributed to rheumatoid arthritis, with a fatal outcome due to baseline disease and surgery complications.

The underestimation of hip pain, mainly when there is no palpable mass, may delay the diagnosis.

Sarcoma sinovial é uma rara malignidade de origem mesenquimal; a abordagem diagnóstica geralmente começa documentando um tumor de tecido mole; no entanto, resulta em um diagnóstico desafiador quando é mais profundo, de pequeno porte ou primário do osso.

O presente relato descreve um paciente que apresentou dor insidiosa no quadril atribuída a artrite reumatoide, com desfecho fatal devido a doenças de base e complicações cirúrgicas.

A subestimação da dor no quadril, principalmente quando não há massa palpável, pode atrasar o diagnóstico.