False-positive cytopathology results for papillary thyroid carcinoma: A trap for thyroid surgeons

OBJECTIVES

Current preoperative diagnosis of thyroid nodules remains imperfect despite recent advances in cytopathology and molecular diagnostics. False positivity in preoperative fine-needle aspiration cytology (FNAC) may lead to overtreatment of patients, including total thyroidectomy, and sometimes to lawsuits for misdiagnosis and malpractice. In this study, we analysed clinical characteristics and pathologic findings in patients with false positivity for papillary thyroid carcinoma (PTC) in FNAC.

METHODS

We retrospectively reviewed permanent pathology results from 3788 patients who underwent thyroid surgery. Among them, 48 patients had lesions that were deemed suspicious or positive (Bethesda class V or VI) for PTC in preoperative FNAC. We reviewed clinic-pathologic data, radiologic findings and surgical planning in these patients.

RESULTS

The prevalence of pathologic thyroiditis was significantly higher among patients with false-positive FNAC results than in those with confirmed PTC (54.2% vs 9.2%, P<.001). The analysis of the permanent pathology reports showed that 26 patients had chronic lymphocytic thyroiditis and 22 patients had no evidence of thyroiditis. Among the patients without pathologic thyroiditis, 19 patients (86.4%) had nodular hyperplasia and three (13.6%) had follicular adenoma, while among the patients with pathologic thyroiditis, seven (26.9%) had no nodule, 14 (53.8%) had nodular hyperplasia, two (7.7%) had hyalinized nodules, two (7.7%) had follicular adenoma and one (3.8%) had a hyalinizing trabecular tumour. In 42 patients, the extent of surgery (total thyroidectomy or hemithyroidectomy) was to be determined according to the intra-operative frozen section biopsy results. Among them, four (10.5%) had inconclusive frozen section results, and 38 (90.5%) had benign results on frozen section.

CONCLUSIONS

Patient counselling about the possibility of false positivity is still important. And the presence of thyroiditis might create confusion in the interpretation of cytopathologic results.

Generation of RUNX3 knockout pigs using CRISPR/Cas9-mediated gene targeting

Pigs are an attractive animal model to study the progression of cancer because of their anatomical and physiological similarities to human. However, the use of pig models for cancer research has been limited by availability of genetically engineered pigs which can recapitulate human cancer progression. Utilizing genome editing technologies such as CRISPR/Cas9 system allows us to generate genetically engineered pigs at a higher efficiency. In this study, specific CRISPR/Cas9 systems were used to target RUNX3, a known tumour suppressor gene, to generate a pig model that can induce gastric cancer in human. First, RUNX3 knockout cell lines carrying genetic modification (monoallelic or biallelic) of RUNX3 were generated by introducing engineered CRISPR/Cas9 system specific to RUNX3 into foetal fibroblast cells. Then, the genetically modified foetal fibroblast cells were used as donor cells for somatic cell nuclear transfer, followed by embryo transfer. We successfully obtained four live RUNX3 knockout piglets from two surrogates. The piglets showed the lack of RUNX3 protein in their internal organ system. Our results demonstrate that the CRISPR/Cas9 system is effective in inducing mutations on a specific locus of genome and the RUNX3 knockout pigs can be useful resources for human cancer research and to develop novel cancer therapies.

Treatment Strategy for Persistent Sciatic Artery and Novel Classification Reflecting Anatomic Status

BACKGROUND

Persistent sciatic artery (PSA) is a relatively rare congenital variant of the lower limb vasculature and can have highly variable clinical presentations. The purpose of this study was to analyze the relationship between PSA anatomy and clinical presentation, and to suggest an optimal management strategy.

METHODS

Between 2001 and 2014, 24 PSAs in 19 patients were diagnosed by computed tomography and referred to the vascular surgery department. Patient demographics, types of PSA and femoral artery, aneurysmal changes, symptoms, and treatment methods were assessed. Additionally, all English literature from 1964 to 2014 was reviewed and compared using the PubMed database (224 PSAs in 171 patients).

RESULTS

PSA was diagnosed in 10 men (52.6%) and nine women (47.4%). PSAs were bilateral in five patients (26.3%) and symptomatic in 12 patients, while in seven patients PSA was found incidentally. According to the Pillet-Gauffre classification, Type 2a was the most common variant (n = 15/24, 62.5%), with unclassifiable types in two limbs. Compared with cases in the literature, the PSA occlusion rate in this study was higher (n = 10/24, 41.7% vs. n = 54/224, 27.5%), but aneurysm incidence was higher in the literature cases (n = 5/24, 20.8% vs. n = 112/224; 50.7%). In this study, 16 limbs (66.6%) were treated conservatively, and six limbs were treated by open surgery, including four bypasses, one amputation, and one thrombo-embolectomy. Endovascular coil embolization was performed in one limb, and a hybrid procedure with stent graft was performed in one limb with PSA aneurysm. Based on the present series and the literature review, a new classification system and treatment option is proposed according to the anatomic status and the presence of aneurysm. According to the new classification, class III was the most common in both the present study (18/24; 75%) and the literature review, and the presence of aneurysm was the most important determinant of surgical treatment.

CONCLUSIONS

The new classification system is simple and provides guidance for management. Limb anatomy of the femoral artery system and the presence of PSA aneurysm should be considered when selecting the optimal treatment. The risk of embolism from the presence of aneurysm is an important factor for treatment, and bypass surgery is mostly required in classes III and IV.