Differential Diagnosis for Enthesopathy along the Greater Trochanters of the Femur
Single Most Likely Diagnosis
- Ankylosing Spondylitis (AS): This is a form of arthritis that primarily affects the spine, but it can also cause enthesopathy, which is inflammation where tendons and ligaments attach to bone. The greater trochanters of the femur are common sites for enthesitis in AS, making it a leading consideration for this presentation.
Other Likely Diagnoses
- Psoriatic Arthritis (PsA): PsA can cause enthesitis, and while it more commonly affects the lower limbs, it can also involve the hip region, including the greater trochanters. The presence of psoriasis or a family history of psoriasis would support this diagnosis.
- Reactive Arthritis: This form of arthritis occurs as a reaction to an infection elsewhere in the body, often in the gastrointestinal tract or the urethra. It can cause enthesitis and is known to affect the lower limbs, including the hip area.
- Enteropathic Arthritis: Associated with inflammatory bowel diseases like Crohn's disease and ulcerative colitis, enteropathic arthritis can cause enthesitis, including in the hip region.
Do Not Miss Diagnoses
- Infectious Causes (e.g., Tuberculosis, Brucellosis): Although less common, infectious causes of enthesitis or osteitis around the greater trochanters must be considered, especially in patients with exposure history or immunocompromised states. These conditions can have severe consequences if not promptly treated.
- Malignancy (e.g., Lymphoma, Metastatic Disease): Rarely, enthesopathy or bone lesions around the greater trochanters can be the initial presentation of a malignancy. A thorough investigation is necessary to rule out such life-threatening conditions.
Rare Diagnoses
- Relapsing Polychondritis: A rare autoimmune disorder that can affect various cartilaginous structures, including potentially causing enthesitis. However, it is more commonly associated with symptoms like auricular chondritis.
- Sarcoidosis: While sarcoidosis can affect bones and joints, its involvement of the entheses around the greater trochanters would be uncommon. It typically presents with pulmonary or dermatological manifestations.
- Whipple's Disease: A rare, systemic bacterial infection that can cause arthralgias and, less commonly, might involve the entheses, though this would be an unusual presentation.