lymphadenopathy is caused by a variety of conditions, including but not limited to infections, autoimmune diseases, and cancers. To your point, the article you

lymphadenopathy is caused by a variety of conditions, including but not limited to infections, autoimmune diseases, and cancers. To your point, the article you linked only states that "she'd noticed lumps in both her armpits two weeks prior - a common symptom of lymphoma." Granulomatous change in the lymph node (when phagocytes eat up the pigment from the tattoo) is not "serious" per say, especially considering that in this case the patient had no other associated symptoms. If you can read the original case report (paywall) that ScienceAlert linked: http://annals.org/aim/article-abstract/2656481/tattoo-pigment-induced-granulomatous-lymphadenopathy-mimicking-lymphoma http://annals.org/aim/article-abstract/2656481/tattoo-pigmen..., you will find that the major point of the article was that getting a good history from a patient with tattoos is important so that you don't misdiagnose them with lymphoma if they do not actually have it.