Incidental Diffuse Sclerosing Variant Papillary Thyroid Cancer in Grave’s Disease

The diffuse sclerosing variant papillary thyroid carcinoma (DSPTC) is an uncommon form of this neoplasm. Some studies describe its high propensity for tumor invasion, metastasis, and mortality compared with classic papillary thyroid carcinoma. Histologic features of DSPTC may resemble diffuse inflammation as seen with Grave’s or Hashimoto’s thyroiditis, which makes initial diagnosis challenging. A 27-year-old female with Noonan’s Syndrome was evaluated on an outpatient basis after developing atrial fibrillation de novo. Thyroid function tests were consistent with hyperthyroidism with TSH: <0.005 (n: 0.300-3.000 uIU/mL), FT4: 3.59 (0.71-1.85 ng/mL) and FT3: 16.77 (n: 2.0-7.0 pmol/L). Diffuse goiter was noted on physical exam, but no ophthalmopathy or dermopathy was present. TRAB and TSI were elevated at 38.4 (n: <16%) and 423% (n: <140%) respectively. A twenty-four-hour radioiodine uptake was 48% (n:10-35%) and described as essentially homogenous with two foci of decreased radiotracer concentration suggestive of cold nodules. Thyroid ultrasound showed diffuse nodularity bilaterally with associated clusters of calcifications and no discrete nodules. No abnormal appearing lymph nodes were identified. Fine-needle aspiration of both nodular areas was positive for DSPTC. Total thyroidectomy with central neck dissection was performed. Gross and microscopic post-surgical pathology confirmed the presence of diffuse sclerosing papillary thyroid cancer, along with local metastasis to one central lymph node. Patient was scheduled for radioactive iodine therapy. Diffuse sclerosing variant is considered an aggressive histotype of papillary thyroid cancer. Ultrasound features include diffuse scattered microcalcifications with or without discrete nodules that may be confused with chronic inflammatory changes. Despite the limited number of cases, DSPTC is recognized to have specific characteristics, a high female to male ratio, and a young patient age. DSPTC has a high potential for aggressive biologic behavior if not treated promptly at the time of diagnosis. When suspected, total thyroidectomy with lymph node excision followed by radioiodine therapy has been proposed as the correct management to decrease the risk of persistent or recurrent disease.