Positive PIK3CA (P.H1047R) Mutation in a Benign Thyroid Nodule of a Patient With Men-1 Syndrome

ABSTRACT Objective The PIK3CA (p.H1047R) mutation has only been identified in advanced poorly differentiated and anaplastic thyroid cancer in the past. We are describing the first reported case of this PIK3CA mutation in a benign thyroid nodule of a patient with multiple endocrine neoplasia type 1 (MEN-1) syndrome, which raises caution to the aggressive treatment approach usually taken when this mutation is identified. Methods A 49-year-old female was found to have primary hyperparathyroidism with multigland disease and tested positive for MEN-1 syndrome. Further evaluation also identified a thyroid nodule, which had indeterminate cytology on fine-needle aspiration biopsy. The ThyroSeq 2.0 assay identified a PIK3CA mutation (p.H1047R, c.3140A>G), which led to a total thyroidectomy. Pathology showed a benign thyroid nodule. Results To our knowledge, this is the first case reporting a PIK3CA (p.H1047R) mutation in a benign thyroid nodule, particularly in a patient with MEN-1 syndrome. Conclusion Clinicians should be aware that this mutation can be identified in benign thyroid nodules and that aggressive management is not always warranted. Further research is needed to improve our understanding of thyroid cancer etiology and improve our ability to identify with high accuracy malignant and benign thyroid nodules when we are faced with indeterminate thyroid nodule cytology.