32-year-old woman with a neck mass   

History and images

Our appreciation is extended to Dr. Abdul Abid, University of Texas Medical Branch, for contributing this case.

History: A 32-year-old woman with history of cervical cancer and adjuvant radiation treatment presented with a neck mass. Ultrasound examination revealed a 3.2-cm right thyroid nodule. A positron emission tomography (PET) scan demonstrated a hypermetabolic right thyroid nodule. Fine-needle aspiration was attempted and cytology reported “atypia of undetermined significance.” The right lobe of the thyroid was excised and sent for histology. A cross section of the thyroid lobe and photomicrographs are provided.

Click the images to enlarge.

What is the most likely diagnosis?
Follicular adenoma
Papillary thyroid carcinoma
Hürthle cell neoplasm
Medullary carcinoma

Which immunohistochemical stains would help with the diagnosis?
Thyroglobulin, thyroid transcription factor-1 (TTF-1)
Cytokeratin, androgen receptors
Cytokeratin 5/6 (CK 5/6), PAX 8
None of the above