Small-Cell Lung Cancer Transformation as a Mechanism of Resistance to Pralsetinib in RET-Rearranged Lung Adenocarcinoma: A Case Report.

The majority of resistance to Rearranged during transfection (RET)-specific tyrosine kinase inhibitors (TKI) described in RET-rearranged non-small cell lung cancer (NSCLC) patients are driven by RET-independent mechanisms. We provide the first case report of a RET-rearranged lung adenocarcinoma (LUAD) transformation into small-cell lung cancer (SCLC) as a mechanism of acquired resistance to pralsetinib. A 43-year-old patient presented with a RET-rearranged LUAD revealed by pleural effusion. After 14 months of response to pralsetinib, biopsy of a progressive pleural lesion found a phenotypic transformation into SCLC. Molecular analysis identified the same RET fusion and TP53 mutation in both primary adenocarcinoma and recurrence as SCLC. The patient achieved partial response after switch to carboplatin and etoposide chemotherapy and presented with progression disease after 6 months. Histological transformation could be a mechanism of resistance to RET-TKIs and rebiopsy should be considered to adapt subsequent treatment.

[Rapid diagnosis for liquid-based fine needle aspiration of thyroid nodules]. / Expérience de diagnostic rapide en cytoponction thyroïdienne monocouche.

INTRODUCTION: The discovery of thyroid nodule can be a source of concern for the patient. Fine-needle aspiration is the gold standard for their evaluation. We establish a new rapid diagnosis procedure for liquid-based fine needle aspiration (LB-FNA) of thyroid nodules. METHODS: Patients were admitted in a day hospital program and a FNA was performed under ultrasound monitoring guidance. The sample followed a dedicated emergency circuit, and the technique was performed within 2 hours. RESULTS: A total of 92 fine needle aspirations were performed between June 2018 and March 2020. Our results showed 21% cases of nondiagnostic, 50% of benign, 21% of atypia of undetermined significance, 2% of follicular neoplasm, 1% of suspicious for malignancy and 5% of malignant. Thanks to these results, 18 patients underwent surgery: 3 benign and 3 nondiagnostic (corresponding to 100% of benign follicular nodules), 2 follicular neoplasm (100% Hürthle cell adenomas), 1 suspicious for malignancy and 3 malignant (100% papillary carcinoma), 6 atypia of undetermined significance (83% of benign lesions, 17% non invasive follicular nodules). CONCLUSION: Rapid diagnosis for thyroid nodules LB-FNA is possible, requiring a specific network involving radiologists, endocrinologists, cytopathologists and surgeons. This is an easy and effective method to improve the quality of patient care.

Poorly differentiated thyroid carcinoma with pleomorphic giant cells-a case report.

Poorly differentiated thyroid carcinoma (PDTC) refers to a malignant tumour that displays an intermediate prognosis between well-differentiated carcinomas and anaplastic thyroid carcinomas (ATC). In the thyroid, pleomorphic giant cells are observed in ATC or in some non-neoplastic thyroid diseases. We described the case of a 43-year-old woman with a 34-mm nodule in her thyroid right lobe. Microscopic examination revealed an encapsulated tumour with a main solid growth pattern and extensive capsular invasion. Multiple images of angioinvasion were observed. There was neither necrosis nor inflammation. Most of the tumour cells were medium-sized and intermingled with pleomorphic giant tumour cells with bizarre features. The immunoprofile (keratins +, TTF1+, Pax 8+) proved their thyroid origin. By NGS, no molecular alteration was identified. The patient was treated by surgery and radioiodine therapy and she has no recurrence after a follow-up of 24 months. Our case meets all the histological criteria of the Turin proposal for PDTC but with pleomorphic giant cells and is very different from ATC according to clinical, histological and immunohistochemical features. Pleomorphic tumour giant cells in thyroid carcinomas could be present in PDTC and do not always represent dedifferentiation and more aggressive carcinoma, thyroid neoplasm.