Impacts of the American Joint Committee on Cancer (AJCC) 8th edition tumor, node, metastasis (TNM) staging system on outcomes of differentiated thyroid cancer in Thai patients.

BACKGROUND: In 2018, the American Joint Committee on Cancer (AJCC) 8th edition (AJCC8) was introduced to replace the previous version (AJCC7) due to superiority of AJCC8 over AJCC7 for better prediction of survival from thyroid cancer. AIM: To compare AJCC staging systems with the American Thyroid Association (ATA) risk classification for the prediction of 5-year disease-free survival (DFS), and 5-year disease-specific survival (DSS) in Thai patients. METHODS: We retrospectively reviewed all patients with histopathologic diagnosis of DTC who were treated at Theptarin Hospital, Bangkok, Thailand from 1987 to 2019. RESULTS: The study cohort included 262 differentiated thyroid cancer (DTC) patients (papillary thyroid cancer 89.7% with a median time of follow-up 7.8 years). The number (%) of patients within each stage group by AJCC7 and AJCC8 respectively are as follows: Stage I: 173 (66.0%) vs. 232 (88.5%), Stage II: 33 (12.6%) vs. 24 (9.2%), Stage III: 36 (13.7%) vs. 2 (0.8%), Stage IV: 20 (7.7%) vs. 4 (1.5%). The ATA high risk group was found in 24.3% of AJCC7 Stage I compared with 23.7% of AJCC8 Stage I. The 5-year DFS rates in patients classified as stages I, II, III, and IV by AJCC8 were 87.9%, 45.8%, 0% and 25%, respectively. The 5-year DSS rates in patients classified as stages I, II, III and IV by AJCC8 were 98.7%, 100%, 100% and 0%, respectively. AJCC8 was more predictive of DFS rate than AJCC7. CONCLUSIONS: Our study is in accord with previous studies that AJCC8 downstage a significant percentage of patients with DTC and correlated with better prognostic validity. However, even a person at low risk for mortality can be at high risk for recurrence.

Epidermoid cyst abscess of the neck masquerading as a thyroid abscess.

SUMMARY: In this case report, we describe a 37-year-old male who presented with fever and tender neck mass. Neck ultrasonography revealed a mixed echogenic multiloculated solid-cystic lesion containing turbid fluid and occupying the right thyroid region. Thyroid function tests showed subclinical hyperthyroidism. The patient was initially diagnosed with thyroid abscess and he was subsequently treated with percutaneous aspiration and i.v. antibiotics; however, his clinical symptoms did not improve. Surgical treatment was then performed and a pathological examination revealed a ruptured epidermoid cyst with abscess formation. No thyroid tissue was identified in the specimen. The patient was discharged uneventfully. However, at the 3-month and 1-year follow-ups, the patient was discovered to have developed subclinical hypothyroidism. Neck ultrasonography revealed a normal thyroid gland. This report demonstrates a rare case of epidermoid cyst abscess in the cervical region, of which initial imaging and abnormal thyroid function tests led to the erroneous diagnosis of thyroid abscess. LEARNING POINTS: Epidermoid cyst abscess at the cervical region can mimic thyroid abscess. Neck ultrasonography cannot distinguish thyroid abscess from epidermoid cyst abscess. Thyroid function may be altered due to the adjacent soft tissue inflammation.

De-differentiation of papillary thyroid carcinoma into squamous cell carcinoma in an elderly patient: A case report.

RATIONALE: The unpredictability of thyroid cancer can be striking, as the disease may rapidly progress to death in some individuals. Herein, we reported a rare case of aggressive papillary thyroid cell carcinoma (PTC) in an elderly patient de-differentiated into squamous cell carcinoma (SCC). PATIENT CONCERNS: We describe a case of a 79-year-old Thai woman presented with hoarseness and neck mass for 2 months and she had been diagnosed with a 3-cm papillary thyroid carcinoma (PTC) in the right side of the thyroid gland. Later on PTC de-differentiated into SCC within 3 years after initial presentation. DIAGNOSIS: De-differentiation from papillary thyroid carcinoma to squamous cell carcinoma. INTERVENTIONS: The patient underwent a total thyroidectomy at the initial hospital and received high dose radioactive iodine (RAI) treatment at our hospital 1 month following the surgery and then was lost to follow-up. Two years later she came back with new development of right solid-cystic neck mass which was found to be recurrent PTC. A radical neck dissection was done and another high dose RAI treatment was given. However, she developed recurrent mass with tenderness at the site above previous solid cystic mass 6 months later. Re-exploration of the neck mass revealed an inflamed midline mass 2 cm with enlarged right lateral cervical lymph nodes. OUTCOMES: A histopathological examination of the midline neck mass showed poorly differentiated SCC with lymphatic invasion. The intermingling of two morphologically distinct tumors, a typical PTC and a poorly differentiated SCC, had been identified in 1 out of 14 excised cervical lymph nodes. The patient underwent external beam radiation without chemotherapy. She is still in stable condition at 18 months post-treatment. LESSONS: This case clearly demonstrated that SCC transformed from a pre-existing PTC. The clinician should consider a possible transformation of papillary thyroid cancer into more aggressive histological types in elderly patients who present with rapidly progressive clinical behavior. However, some patients could have long-term survival if the tumor did not transform into anaplastic thyroid cancer.