Since how long lump ?
Any previous treatment history?
Osteoarthritis, the most common form of arthritis, often affects the hands. When it does, it often causes local inflammation of the distal interphalangeal joints (DIP or last row) and proximal interphalangeal joints (PIP or next to last row). This inflammation causes the joints to swell and hurt. The lumps that form are called Heberden's nodes (DIP) and Bouchard's nodes (PIP). Involvement of the base of the thumb may also cause a lumpiness or squared-off appearance.
Gout also causes lumps in the fingers. Gout may cause inflammation of the interphalangeal joints of the fingers. When this occurs, it may be indistinguishable from a flare of osteoarthritis
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