We report a case of a 57-year-old postmenopausal woman with an autonomously functioning thyroid adenoma spontaneously developing Graves' disease (GD) as documented by I-123 scintigraphy. To date, anecdotal case reports citing the progression of an autonomous nodule to GD have documented either a major thyroidal insult, spontaneous or therapeutic, or the activation of thyroid tissue by circulating thyroid stimulating IgG, with variable progression characteristics. In contradiction to the proposed inciting factors, our patient underwent a minimally invasive fine needle aspiration biopsy followed by suppressive pharmacotherapy. Her antithyroid antibody assay detected low titers of thyroperoxidase antibody (<10 U/mL). We conclude that this is a rare case of autonomously functioning adenoma where neither significant thyroid tissue damage nor the presence of thyroid stimulating IgG can be implicated as an inciting trigger in its progression to GD.