Fine-Needle Aspiration with Immunohistochemistry Using a Modified Scrape Cell Block Technique for the Diagnosis of Thyroid and Parathyroid Nodules

Immunohistochemical Profile of Parathyroid Tumours: A Comprehensive Review

Immunohistochemistry remains an indispensable tool in diagnostic surgical pathology. In parathyroid tumours, it has four main applications: to detect (1) loss of parafibromin; (2) other manifestations of an aberrant immunophenotype hinting towards carcinoma; (3) histogenesis of a neck mass and (4) pathogenetic events, including features of tumour microenvironment and immune landscape. Parafibromin stain is mandatory to identify the new entity of parafibromin-deficient parathyroid neoplasm, defined in the WHO classification (2022). Loss of parafibromin indicates a greater probability of malignant course and should trigger the search for inherited or somatic CDC73 mutations. Aberrant immunophenotype is characterised by a set of markers that are lost (parafibromin), down-regulated (e.g., APC protein, p27 protein, calcium-sensing receptor) or up-regulated (e.g., proliferation activity by Ki-67 exceeding 5%) in parathyroid carcinoma compared to benign parathyroid disease. Aberrant immunophenotype is not the final proof of malignancy but should prompt the search for the definitive criteria for carcinoma. Histogenetic studies can be necessary for differential diagnosis between thyroid vs. parathyroid origin of cervical or intrathyroidal mass; detection of parathyroid hormone (PTH), chromogranin A, TTF-1, calcitonin or CD56 can be helpful. Finally, immunohistochemistry is useful in pathogenetic studies due to its ability to highlight both the presence and the tissue location of certain proteins. The main markers and challenges (technological variations, heterogeneity) are discussed here in the light of the current WHO classification (2022) of parathyroid tumours.

Major Clues and Pitfalls in the Differential Diagnosis of Parathyroid and Thyroid Lesions Using Fine Needle Aspiration Cytology

Background: It is difficult to distinguish parathyroid lesions (PLs) from thyroid lesions using fine needle aspiration cytology (FNAC) because of their proximity and their similar cytomorphological features. Methods: FNAC smears of 46 patients with pathologically proven PLs that were histologically diagnosed as parathyroid adenoma (PA, n = 35), parathyroid hyperplasia (PH, n = 3), atypical parathyroid adenoma (APA, n = 1), and parathyroid carcinoma (PC, n = 7) were retrospectively reviewed and analyzed. Results: Our initial cytological diagnoses indicated correct diagnoses in 31 of 46 PL patients (67%). The 15 erroneous diagnoses were 5 patients with non-specific benign disease (11%), 4 with nodular hyperplasia of the thyroid (9%), 5 with atypical cells (11%), and 1 with a metastatic papillary thyroid carcinoma (2%). Follicular pattern, papillary structures, colloid-like material, and macrophages, which often suggest thyroid lesions, were also present in some PLs. We found that branching capillaries along the papillary structures, stippled nuclear chromatin, and frequent occurrence of naked nuclei were useful for determining a parathyroid origin. Conclusions: It is important to be aware that PLs are frequently mistaken for thyroid lesions based on FNAC. The specific and unique characteristics of PLs identified here may be helpful in diagnosis.

Manufactured Cell Blocks: Turning Smears into Sections

Whilst cytological smears are still the basis of cytodiagnosis, there is an increasing role for ancillary testing. Specimens obtained are not always optimal, often with limited material for ancillary studies. Several reports have described the utility of scraping material from cytological smears to manufacture cell blocks to provide material for ancillary studies. Our objective was a retrospective review of the PathWest (QE2) experience with manufactured cell blocks (mCB) over the last 10 years. A total of 178 fine-needle aspiration cases with mCB were extracted from the PathWest database. Data were subdivided into: lymph node (89), breast (31), thyroid (23), soft tissue (13), liver (11), and other sites (11) and were analysed. All available material was reviewed. Diagnostic material was identified in 163 mCB (91.6%). Immunohistochemistry (IHC) was performed on 149 cases. Positive IHC staining was seen in 139 cases (93.3%) and advanced the diagnosis in 119 cases (79.9%). Molecular studies were performed on 38 mCB with adequate DNA obtained in 37 cases (97.3%). Our review has demonstrated that cellular material scraped from air-dried or prefixed smears can be made into cell blocks. Antigen preservation is adequate to provide diagnostically useful results with IHC whilst DNA integrity is preserved to allow molecular analysis.

Diagnostic validity of fine-needle capillary cytology in palpable tumours at the Oncology Institute of Peru

Objective

To evaluate the diagnostic validity of fine-needle capillary cytology (FNCC) in palpable tumours.

Material and methods

A retrospective, single-tray, cross-sectional diagnostic test study was carried out. We reviewed the cytological reports of the case files of the Cytology Unit of the Northern Regional Institute of Neoplastic Diseases (IREN) from January 2012 to December 2016.

Results

A total of 332 patients were selected, with an average age of 54.77 years (range 13-90 years); 61.4% of patients were female. The most frequent anatomical sites were lymph nodes (49.7%), thyroid (13.3%), breast (12.3%) and soft tissues (11.4%). Twenty-five cytologies did not have a histological correlation and six showed an atypical result. In the lymph node study, the most frequent pathology was metastatic carcinoma (49.7%), followed by lymphoma (13.3%). The FNCC had a sensitivity of 99.55%, a specificity of 98.77%, a positive predictive value of 99.55% and a negative predictive value of 98.77%. The positive likelihood ratio was 80.63%.

Conclusions

FNCC is a useful, safe, reliable and economical ambulatory technique with minimal complications and high diagnostic accuracy.