Debilitating musculoskeletal pain and stiffness with letrozole and exemestane : associated tenosynovial changes on magnetic resonance imaging

Arthralgia, skeletal and muscle pain have been reported in postmenopausal women under treatment with third generation aromatase inhibitors (AIs). However, the pathogenesis and anatomic correlate of musculoskeletal pains have not been thoroughly evaluated. Moreover, the impact of AI-induced musculoskeletal symptoms on normal daily functioning needs to be further explored. We examined 12 consecutive non-metastatic breast cancer patients who reported severe musculoskeletal pain under a third generation AI; 11 were on letrozole and 1 on exemestane. Clinical rheumatological examination and serum biochemistry were performed. Radiological evaluation of the hand/wrist joints were performed using ultrasound (US) and/or magnetic resonance imaging (MRI). The most common reported symptom was severe early morning stiffness and hand/wrist pain causing impaired ability to completely close/stretch the hand/fingers and to perform daily activities and work-related skills. Six patients had to discontinue treatment due to severe symptoms. Trigger finger and carpal tunnel syndrome were the most frequently reported clinical signs. US showed fluid in the tendon sheath surrounding the digital flexor tendons. On MRI, an enhancement and thickening of the tendon sheath was a constant finding in all 12 patients. Musculoskeletal pains in breast cancer patients under third generation AIs can be severe, debilitating, and can limit compliance. Characteristic tenosynovial, and in some patients joint changes on US and MRI were observed in this series and have not been reported before.