Differential Diagnoses for Left Wrist Bony Prominence Near the Thumb

Primary Differential Diagnoses

The American College of Rheumatology suggests that bony enlargement with or without deformity is a clinical hallmark of hand osteoarthritis affecting the thumb base, typically presenting with pain on usage and mild morning stiffness, with symptoms often intermittent 1
The American College of Radiology recommends plain radiographs showing joint space narrowing, osteophytes, subchondral sclerosis, and subchondral cysts to confirm the diagnosis of thumb base osteoarthritis 2
Risk factors for thumb base osteoarthritis include female sex, age over 40, menopausal status, family history, and prior hand injury, according to the American College of Rheumatology 1

The American College of Radiology indicates that radiography is always indicated as initial imaging for suspected wrist pathology, with a 3-view examination being standard, to look for joint space narrowing, osteophytes, subchondral sclerosis, and cysts characteristic of osteoarthritis 4, 5
The American College of Rheumatology suggests that CT without IV contrast is commonly used to exclude or confirm suspected wrist pathology when radiographs are equivocal, and MRI without IV contrast can detect occult fractures and soft tissue pathology 4, 5
Blood tests are not required for diagnosis of hand osteoarthritis but may be needed to exclude coexistent inflammatory disease if marked inflammatory symptoms are present, according to the American College of Rheumatology 1, 6

The location near the thumb base strongly suggests thumb carpometacarpal osteoarthritis as the primary diagnosis, as this is a characteristic target site for osteoarthritis, and the presence of true bony prominence further supports degenerative rather than inflammatory pathology, according to the American College of Rheumatology 1
Gout can superimpose on pre-existing hand osteoarthritis, complicating the clinical picture, and presents with acute inflammatory episodes rather than chronic bony prominence, according to the European League Against Rheumatism 3