Abstract
A woman in her 70s was admitted to the Emergency Department with non-specific symptoms, such as fever, cough, dysuria, and hip pain with limited mobility, along with elevated inflammatory markers. She was initially diagnosed with a lower respiratory tract infection. However, she was readmitted to the hospital three days later due to worsening symptoms. The patient was eventually diagnosed with a secondary psoas abscess caused by underlying appendicitis and was successfully treated. This case highlights the diagnostic challenge of psoas abscess and underscores the importance of considering this uncommon condition in patients presenting with hip pain, fever and elevated inflammatory markers.