SUN-609 Diagnosis of Diffuse Sclerosing Variant of Papillary Thyroid Cancer Confounded by Concurrent Postpartum Thyroiditis

Abstract Diffuse sclerosing variant (DSV) is a rare subtype of papillary thyroid cancer (PTC). Whether it represents a higher grade subtype than conventional PTC is not quite clear. Furthermore, there are limited data on its long-term outcome and its molecular genetics. In this report, we studied all cases of DSV PTC seen at our center during the last 20 years. Out of more than 6000 patients (pts) with differentiated thyroid cancer, only 37 were DSV. We reviewed the clinical and histopathological features, management and outcome of these cases. In addition, molecular genetics is partially achieved; 17 out of these 37 cases have been genotyped for BRAFV600E, TERT promotor mutations, NRAS, HRAS and KRAS mutations. The molecular profiling of the other 20 cases is being done. A total of 37 pts were studied {(12 Males:25 Females, median age 21 years (8-89)}. One pt had lobectomy and the other 36 pts (97.3%) had a total thyroidectomy. Central only (4 pts) or central/lateral lymph node dissection (29 pts) were performed. The median tumor size was 4.5 cm (1.5-8.1). The tumor was multifocal in 27 cases (73%), with extrathyroidal invasion in 27 (73%) and lymphovascular invasion in 24 pts (64.8%). A background lymphocytic thyroiditis was present in 12 pts (32.4%). Lymph node metastases were present in 34 pts (92%) and distant metastases in 13 pts (35%). The sites of metastasis are lungs in 12 pts (32.4%) and lungs and bone in 1 pt. Twenty pts (54.1%) were in TNM8 stage 1, 10 pts (27%) in stage 2, 1 (2.7%) in stage 4a, 3 (8.1%) in stage 4b and 3 unstageable. The ATA risk classification for these pts was 4 pts (10.8%) in low, 12 (32.4%) in intermediate, 19 (51.4%) in high-risk groups and 2 could not be assessed. I-131 was administered to 33 pts (89.2%). The median administered activity was 136 mCi (46-218). Fifteen pts (40.5%) received additional therapies (3 surgeries, 7 RAI, 5 surgeries, and RAI). In 17 pts (46%) which were genotyped, only 3 tumors (8.1%) had BRAFV600E mutation, 1 (2.7%) had TERT promotor C228T mutation and none had RAS mutations. At the last follow up, 15 pts (40.5%) achieved an excellent response, 9 (24%) an indeterminate response, 6 (16.2%) with a structural disease, and 7 (19%) were lost for follow up. Conclusion: DSV PTC is a rare variant, occurs mostly in adolescent and young pts, characterized by aggressive histopathological features and high rates of lymph node and distant metastases but the commonly reported mutations in PTC are rare in DSV and mortality is absent.

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

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.1820 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A891-A892

Author(s):

Nicolle Canales ◽

Yadiel Rivera Nieves ◽

Nydia Ivette Burgos Ortega ◽

Janet Marie Colon Castellano ◽

Nicole Hernández Cordero ◽

...

Keyword(s):

Thyroid Cancer ◽

Lymph Node ◽

Papillary Thyroid Carcinoma ◽

Thyroid Carcinoma ◽

Total Thyroidectomy ◽

Papillary Thyroid Cancer ◽

Outpatient Basis ◽

Thyroid Function Tests ◽

Papillary Thyroid ◽

Diffuse Sclerosing Variant

Abstract 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.

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