3D Virtual Histopathology by Phase-Contrast X-Ray Micro-CT for Follicular Thyroid Neoplasms

Histological analysis is the core of follicular thyroid carcinoma (FTC) classification. The histopathological criteria of capsular and vascular invasion define malignancy and aggressiveness of FTC. Analysis of multiple sections is cumbersome and as only a minute tissue fraction is analyzed during histopathology, under-sampling remains a problem. Application of an efficient tool for complete tissue imaging in 3D would speed-up diagnosis and increase accuracy. We show that X-ray propagation-based imaging (XPBI) of paraffin-embedded tissue blocks is a valuable complementary method for follicular thyroid carcinoma diagnosis and assessment. It enables a fast, non-destructive and accurate 3D virtual histology of the FTC resection specimen. We demonstrate that XPBI virtual slices can reliably evaluate capsular invasions. Then we discuss the accessible morphological information from XPBI and their significance for vascular invasion diagnosis. We show 3D morphological information that allow to discern vascular invasions. The results are validated by comparing XPBI images with clinically accepted histology slides revised by and under supervision of two experienced endocrine pathologists.

Total thyroidectomy can still remain the method of choice in some Bethesda III cases

BACKGROUND

The latest WHO classification of tumours of endocrine organs defines new units of borderline thyroid tumours (BTT). The aim of our study was to evaluate ultrasonographic and cytological features, mutation profile and surgery treatment in rare thyroid tumours.

METHODS

An analysis of 8 BTT out of 487 patients, who underwent thyroid surgery between June 2016 and June 2020. The definitive diagnosis was made postoperatively by extensive histopathological examination. Molecular genetic analysis of genes associated with thyroid oncology (BRAF, HRAS, KRAS, NRAS, TERT, TP53, fused genes) were performed from one FNAB, and 7 formalin-fixed paraffin-embedded (FFPE) samples.

RESULTS

BTT were found in a total of 8 patients (1.6%), with a predominance of men with respect to other operated patients. FNAB samples were classified in the Bethesda system as Bethesda I, Bethesda II and Bethesda III in one, four and three cases, respectively. Hemithyroidectomy and total thyroidectomy were performed equally in four patients. The histopathological diagnosis revealed non-invasive encapsulated follicular neoplasm with papillary-like nuclear features (NIFTP) in three patients, follicular tumour of uncertain malignant potential (FT-UMP) in three patients, well differentiated tumour of uncertain malignant potential (WDT-UMP) in one patient, and hyalinizing trabecular tumour (HTT) in one case. In NIFTP cases mutation in HRAS gene in one patient together with probable pathogenic variant in TP53 gene and in NRAS gene in two patients were detected. In HTT patient PAX8/GLIS3 fusion gene was detected.

CONCLUSION

The surgical treatment of BTT is necessarily individual influenced by preoperative clinical, ultrasonographic, cytological and molecular genetic findings, and the presence of other comorbidities.

Molecular trait of follicular-patterned thyroid neoplasms defined by MALDI-imaging

In the field of thyroid neoplasms, the most interesting recent change regards the introduction of a new terminology for follicular-patterned thyroid tumors, named Noninvasive Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP). This pre-malignant tumor is considered to be the putative precursor of invasive carcinoma. However, given that several issues are still unresolved, the application of ancillary tools, based on omics-techniques, may improve the clinical management of these challenging cases. The present paper highlights the proteomic profiles of a series of NIFTPs submitted to Fine Needle Aspirations (FNAs) and analysed by MALDI-imaging in order to confirm the heterogeneous phenotype of nodules included in the present NIFTP terminology and to underline the necessity of more accurate biomarkers that can be used for their characterization. Ethical and economic implications in terms of healthcare costs, operative risks, morbidity, as well as the potential need for lifelong hormone replacement therapy, seem to be significant reasons to approach the characterization of NIFTPs using alternative tools such as MALDI-MSI.

Practice Paradigms Before and After Introduction of the Diagnosis-Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP): an Institutional Experience

The recently adopted terminology of "Noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) reflects the indolent behavior of these tumors. In contrast to conventional papillary thyroid carcinomas, NIFTP can be managed conservatively. The purpose of this study was to investigate changes in surgical and pathologic practice patterns at our institution since the introduction of the NIFTP diagnosis in 2016. A retrospective analysis of all thyroid specimens received in our laboratory between January 2015 and April 2017 was performed. The final cohort consisted of 1508 thyroidectomy specimens from 1508 patients (1153 (76.5%) women and 355 (23.5%) men), of which 1011 (67%) were total thyroidectomies and 497 (33%) were partial thyroidectomies. There were 558 (69.2%) total thyroidectomies and 248 (30.8%) partial thyroidectomies performed prior to introduction of the NIFTP diagnosis and 453 (64.5%) and 249 (35.5%) total and partial thyroidectomies, respectively, after the change in nomenclature. Within a year following the initial use of this diagnosis, 67 NIFTP cases were identified (9.5% of all thyroidectomies), whereas compared with the year preceding it, malignant diagnoses decreased from 54.5 (439) to 44.6% (313), and the benign category remained unchanged from 44.5 (367) to 45.9% (322). For the entirely submitted 67 NIFTP cases, the mean number of blocks submitted was 14.7 (0.98 blocks/g); for malignant lesions 17.7 (0.92 blocks/g); and for benign lesions 16.6 (0.75 blocks/g). The results of our study suggest that NIFTP are encountered in almost 10% of thyroidectomies at our institution with expected shifts in cytology and surgical pathology diagnoses as a result of the change in nomenclature. During this time period, significant shifts towards less aggressive surgical management were not observed. All 67 NIFTP nodules were submitted entirely with no significant difference in the number of cassettes submitted for NIFTP nodules as compared with follicular variant papillary thyroid carcinoma (PTC), classic variant PTC, or follicular adenoma.