Tenosynovial chondromatosis of the flexor pollicis longus tendon: A subtype of primary synovial chondromatosis

Primary synovial chondromatosis is a rare benign neoplastic process, in which cartilaginous nodules are produced in the subsynovial tissue. It has 3 main subtypes (intra-articular, tenosynovial and bursal). We present the case of a 61-year-old female, with a mass involving her right thumb for at least 5 years, which had recently increased in size. X-ray showed a soft tissue mass, without calcification or any underlying bony abnormality. Ultrasound and MRI showed a 6-cm mass surrounding the right flexor pollicis longus tendon of the right thumb. The patient went on to have surgical resection and was given a diagnosis of tenosynovial chondromatosis.