One needs also to consider drug-induced accelerated nodulosis. I used to see it more often in the 1990s from methotrexate, but since then, it has also been described with other drugs like TNF inhibitors and leflunomide (Patatanian & Thompson, PMID 12222551, Ahmed et al., PMID 11470988, Akiyama e...

If asymptomatic, you are always best leaving the nodule alone. If a nodule is irksome (e.g., symptomatic), cutaneous and not associated/adherent to a tendon or ligament, injection is a safe effective treatment. I recommend Ching et al., PMID 1450803, a placebo-controlled trial. Other references are ...