Diagnostic pitfalls in the evaluation of fine needle aspiration cytology of the thyroid: correlation with histopathology in 260 cases

Objectives:  Fine needle aspiration cytology (FNAC) of the thyroid is a non-invasive, cost-effective screening procedure that is valuable for distinguishing neoplastic lesions from non-neoplastic nodules. The aim of this study was to determine the diagnostic accuracy of FNACs performed at our institution by correlating FNAC results with histopathological diagnoses.
Methods:  Two hundred and seventy-one aspiration cytology specimens followed by thyroidectomy were included in the study, and the results of 260 adequate FNACs were compared with their histological diagnoses.
Results:  The sensitivity and specificity of thyroid FNAC for detecting neoplasia were 92.6% and 91.6%, respectively. There were 15 (5.7%) false positives and six (2.3%) false negatives.
Conclusions:  The results showed that follicular cells that exhibit some of the features of papillary carcinoma could be observed in a cytology slide of Hashimoto's thyroiditis, leading to a diagnostic pitfall. In addition, cellularity and overlapping cytological criteria in hyperplasia might lead to a false diagnosis.     

Intraoperative cytology (squash smear) in neurosurgical practice – pitfalls in diagnosis experience based on 3057 samples from a single institution

OBJECTIVES: The smear technique is challenging for a neuropathologist where rapid and accurate diagnosis is to be given on small biopsies. The present study, a large retrospective analysis of squash smears in neurosurgical practice, was conducted to assess the usefulness, accuracy and the diagnostic pitfalls of smear diagnosis. METHODS: The authors analysed 3057 central nervous system (CNS) lesions sent for intraoperative cytology (IC) during the years 1988-2005. The stain used was 1% alcoholic toluidine blue. The smear diagnosis was compared with the histological diagnosis to evaluate the diagnostic accuracy. RESULTS: Diagnostic accuracy irrespective of lesion and site ranged from 83.0% to 86.0% per year (mean=85%). The highest rate of correlation among common brain tumours was noted in schwannoma (96.6%) and pituitary adenoma (92.2%), followed by meningiomas (88.9%), astrocytomas (88.4%), chordomas (86.4%) and neurocytomas (86.9%). Infections as a whole contributed 380 cases. The most common infection was tuberculosis. CONCLUSION: This is the largest series reported from India to the best of our knowledge. Squash smear technique is a very reliable and rapid method of intraoperative diagnosis. Knowledge of clinical and neuroimaging details helps the experienced neuropathologist to improve the diagnostic accuracy.     

Determination of pyrimidine phosphoribosyltransferase and uridine kinase activities by an assay with DEAE-paper discs

Rapid (6 min washing step) and reliable methods for determining uridine kinase and pyrimidine phosphoribosyltransferase activities were devised. These procedures, consisting of a spotting technique on DEAE-discs followed by washing and elution, permitted the consistent recovery of about 90% of the nucleoside 5'-phosphate esters formed from radioactive precursors, either uridine or 5-fluorouracil, respectively. Of these precursors, less than 2% were retained on the discs. Direct counting of the discs (without elution), filtration by either gravity or suction, and the use of so-called activation of discs have not proved advantageous.     

Thyroid Bethesda reporting category, ‘suspicious for papillary thyroid carcinoma’, pitfalls and clues to optimize the use of this category

A. Mahajan, X. Lin and R. Nayar Thyroid Bethesda reporting category, ‘suspicious for papillary thyroid carcinoma’, pitfalls and clues to optimize the use of this category Objective: The Bethesda System of Reporting Thyroid Cytopathology classifies the indeterminate categories based on their differing risks of malignancy, as atypia of undetermined significance (AUS), follicular neoplasm/suspicious for follicular neoplasm (FLUS) and suspicious for malignancy. The vast majority of cases of the last category are suspicious for papillary thyroid carcinoma (PTC). The aim of the present study was to identify the pitfalls and clues to improve the usage of the suspicious category as well as improve its outcome of malignancy. Methods: We reviewed the cytological features on air dried Diff‐Quik® and alcohol‐fixed Papanicolaou smears from 54 thyroid fine needle aspirates (FNAs) with surgical follow‐up that were originally diagnosed as suspicious. Procedure data/specimen adequacy was correlated and follow‐up histology reports were reviewed after our cytological review was completed. Incidental PTC that was not the target of the FNA was excluded from the calculations for correlation. Results: In our cytological review, we retained a diagnosis of suspicious in 18 of the 54 cases and the remaining 36 were re‐categorized as follows: 6 malignant, 10 neoplasm (which is used in our centre instead of FLUS) and 20 AUS. The reasons for overcall of suspicious cases included pseudopapillae, syncytial sheets, nuclear grooves and pinpoint nucleoli in chronic lymphocytic thyroiditis and Hürthle cell neoplasms, and intranuclear inclusions in parathyroid adenoma, hyalinizing trabecular adenoma and mesenchymal repair. The primary reasons for undercall of PTC as suspicious included cystic aspirates with minor features of PTC such as histiocytoid cells, bubblegum colloid, syncytial sheets and cellular swirls. Cases with cytoplasm similar to Hürthle cells were also noted to cause difficulty in accurate classification. Conclusions: Recognition of these pitfalls and clues can help improve diagnosis, patient treatment and consequently reduce the number of unnecessary thyroidectomies.     

Usefulness of oral cytopathology in the diagnosis of infectious diseases

P. H. Braz‐Silva, M. H. C. G. Magalhães, V. Hofman, K. L. Ortega, M. I. Ilie, G. Odin, P. Vielh and P. Hofman Usefulness of oral cytopathology in the diagnosis of infectious diseases In recent years, the incidence of oral opportunistic infections has increased, partly due to the widespread implementation of organ and bone marrow transplantation and the increase in the prevalence of human immunodeficiency virus (HIV) infection. Cytology can be used as a rapid, inexpensive and simple routine procedure in diagnosing infectious diseases of the mouth. Moreover, ancillary methods can be applied to cytological samples, increasing the specificity and sensitivity for the diagnosis of infectious diseases. This review describes the cytopathological features of the main viral, fungal, bacterial and parasitic infections of the mouth. Cytological techniques of specimen collection, identification of infectious agents by cytomorphological approaches and ancillary methods, and diagnostic pitfalls will be discussed.     

Characteristic cytological features of histological grade one (G1) breast carcinomas in fine needle aspirates

Objective:  To analyse the spectrum of nuclear features as well as dissociation pattern found in fine needle aspirates (FNAC) from histological grade 1 breast carcinomas and evaluate the critical cytological features of these lesions.
Material and methods:  The material consisted of FNAC smears from 494 histologically confirmed grade 1 breast carcinomas. All smears were revaluated for cell dissociation pattern, nuclear size, cell uniformity, nucleoli, nuclear margin and chromatin pattern. All features were compared with the histological subtype and cytological grading.
Results:  73.9% of the cases were cytological grade 1, 24.3% were grade 2 and 1.8% were grade 3. The majority of the cases had a cell dissociation pattern showing both a population of single carcinoma cells and cell clusters (65.9%). Practically all tumours had a granular chromatin pattern (94.7%) and a slightly irregular nuclear margin with folds and grooves (94%) irrespective of histological subtype and cytological grading. Nucleoli were mostly indistinct or small (74%), whereas 24.3% were noticeable and 1.7% abnormal. Practically all cases revealed some degree of pleomorphism with 74.3% showing mild and 22.4% a distinct pleomorphism. A small subgroup of IDC was classified as monomorphic (3.3%). Almost all tumours had nuclear sizes in the range of 2–4 × RBC (96.9%).
Conclusion:  Not all histological grade 1 carcinomas are cytological grade 1. About 25% were grade 2, and a small subpopulation reached grade 3. The typical/average findings in FNAC from grade 1 breast carcinomas were a population of both groups and single cells showing mild pleomorphism, granular chromatin, slightly irregular nuclear margin, indistinct nucleolus and nuclear size 2–4 × RBC.     

Fine needle aspiration cytology of salivary gland lesions: advantages and pitfalls

Fine needle aspiration cytology (FNAC) was performed on 52 patients with salivary gland lesions. A definitive cytodiagnosis was possible in 45 cases: a sensitivity of 89% and a specificity of 94% was achieved. The pitfalls of FNAC of salivary gland lesions are reflected by the false positive and false negative rates which were 4%. Errors of cytodiagnosis are due to the morphological variability of these tumours which make sampling and interpretation difficult.