We report a case of idiopathic tumoral calcinosis localized to the thumb without prior trauma or surgery. Initial physical examination and imaging studies were suggestive of more common etiologies of thumb pain. After treatment failure, a biopsy specimen revealed calcium phosphate salt deposition in the soft tissue around the metacarpophalangeal joint, which was treated by excision of the tumoral calcinosis masses. Tumoral calcinosis can occur idiopathically in the hand and digits and should be considered when other more common pathologies of thumb pain have been ruled out.