Cytopathology of non-invasive follicular thyroid neoplasm with papillary-like nuclear features: A comparative study with similar patterned papillary thyroid carcinoma variants.

OBJECTIVE: Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a recently described, indolent thyroid tumor, with well-defined histopathological diagnostic criteria. Cytology features are not well documented. We reviewed cytology of histologically proven cases of NIFTP and some of its common differentials to look for salient diagnostic features. METHODS: Cases reported on histopathology as follicular variant of papillary thyroid carcinoma (FVPTC), or NIFTP between July 2015 and April 2017 having available cytology smears were retrieved and reclassified as NIFTP, FVPTC, and classical papillary thyroid carcinoma with predominant follicular pattern (PTC-FP). Cytological features were assessed, classified as per The Bethesda System for Reporting Cytopathology and compared. RESULTS: There were 23 NIFTP cases, 18 FVPTC and 8 PTC-FP. A microfollicle-predominant pattern was seen in all. Nuclear score was 2 in most NIFTP cases (61%). Pseudoinclusions were absent. NIFTP showed features of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) (III) in 61%, follicular neoplasm/suspicious for a follicular neoplasm (FN/SFN) (IV) in 35% and suspicious for malignancy (SFM) (V) in 4%. Most of the FVPTCs were also called FN/SFN (IV) (56%) or AUS/FLUS (III) (22%). Nuclear features did not statistically differ from NIFTP. PTC-FP showed high-grade cytology in 75%, and higher nuclear score (3 in 75%) in contrast to NIFTP (P = .003). CONCLUSION: NIFTP and FVPTC show a similar distribution among the Bethesda categories hence precluding conclusive distinction on cytology. PTC-FP, in contrast, was found to have a statistically significant higher nuclear score and more commonly showed malignant cytology.

Adenocarcinoma predominant pattern subtyping and nuclear grading in cytology: Is there a role in prognostication of advanced pulmonary adenocarcinomas?

INTRODUCTION: Primary lung adenocarcinomas (ADs) show varied architectural patterns, and pattern-based subtyping of ADs is currently recommended due to prognostic implications. Predicting AD patterns on cytology is challenging; however, cytological nuclear features appear to correlate with histological grade and survival in early stage lung ADs. The feasibility and value of AD pattern prediction and nuclear grading on cytology in advanced lung ADs is not known. We aimed to predict patterns and analyse nuclear features on cytology and evaluate their role in prognostication. METHODS: One-hundred patients of Stage III/IV lung AD with available matched cytology and histology samples were included. Cyto-patterns based on cell arrangement patterns (flat sheets vs three-dimensional clusters vs papillae) and cyto-nuclear score based on nuclear features (size, shape, contour), nucleoli (macronucleoli vs prominent vs inconspicuous), and nuclear chromatin were determined, and correlated with predominant histological-pattern observed on the matched small biopsy and outcome. RESULTS: Higher cyto-nuclear scores were observed with high-grade histo-patterns (solid, micropapillary and cribriform), while the predicted cyto-patterns did not correspond to the predominant pattern on histology in 77% cases. Highest cyto-histo agreement was observed for solid pattern (72%). High grade histo-patterns and cyto-nuclear scores > 3 showed a trend towards inferior survival (not significant). CONCLUSIONS: Nuclear grade scoring on cytology is simple to perform, and is predictive of high grade patterns. Its inclusion in routine reporting of cytology samples of lung ADs may be valuable.

An institutional experience with The Paris System: A paradigm shift from ambiguous terminology to more objective criteria for reporting urine cytology.

BACKGROUND: Urine cytology is a highly specific modality for diagnosing high-grade urothelial carcinoma (HGUC), but plagued by low sensitivity and wide inter-observer variability mainly ascribed to the lack of an established template of reporting. The Paris System (TPS) working group proposed such a template at the 2013 International Congress of Cytology, replete with objective criteria for categorising specimens into one of the seven categories: non-diagnostic, negative for HGUC, atypical urothelial cells, suspicious for HGUC, HGUC, low-grade urothelial neoplasm and others (including non-malignant entities). This study was undertaken to determine the impact of TPS criteria in the morphological interpretation of urine samples. METHODS: A total of 255 voided urine specimens from 97 patients who had follow-up biopsies were re-assessed according to TPS criteria and correlated with the final histological diagnosis. RESULTS: Sixty-three patients were diagnosed with HGUC, and 34 had low-grade papillary UC on biopsy. Earlier samples from 40 (41.2%) patients were categorised as merely "atypical" wheereas the "positive for malignancy" category was assigned to 33 (34%) patients. After re-evaluation of the same cases using TPS criteria, cytological features in 44 (69.8%) out of 63 HGUC patients were correctly recognised as HGUC and samples from additional seven patients were re-categorised as suspicious for HGUC (total 81%). The sensitivity of the HGUC category in predicting HGUC was 69.8% which rose to 81% when HGUC was grouped with suspicious for HGUC category. CONCLUSION: The criteria outlined by TPS facilitated the standardisation of urine cytology reporting and significantly increased the sensitivity of diagnosing HGUC.

Cytomorphology of neuroendocrine tumours of the gallbladder.

OBJECTIVE: Gallbladder neuroendocrine tumours (GB-NETs) are rare and account for 0.5% of all NETs. GB-NETs have an aggressive behaviour, which depends on the tumour grade. The cytomorphological spectrum of these tumours has never been described in detail. The present study evaluates the cytological features of GB-NETs and grades them according to the World Health Organization (WHO) classification. Furthermore, the expression of thyroid transcription factor-1 (TTF-1) has not been investigated previously in GB-NETs, although found in a subset of extrapulmonary NETs. METHODS: Twenty cases of GB-NET among 875 gallbladder carcinomas diagnosed by ultrasound-guided fine needle aspiration cytology (FNAC) over a period of nearly 4 years were studied. The following parameters were evaluated: architectural pattern, nuclear chromatin, nucleoli, mitoses, necrosis, moulding, apoptosis and smudge cells. Cases were categorized into well-differentiated (grades 1 and 2), small cell carcinoma (SCC) (grade 3) and mixed adenoneuroendocrine carcinoma. Nuclear positivity for TTF-1 was considered as positive. RESULTS: Morphologically, tumour cells were mainly arranged in rosettes in the well-differentiated category; sudden anisonucleosis and rare nuclear moulding with or without mitotic figures were other features. Eleven cases of SCC showed prominent nuclear moulding with frequent smudge cells, mitoses, apoptosis and necrosis. Three mixed adenoneuroendocrine carcinomas showed papillary fragments and an acinar arrangement of tumour cells. Four of the nine SCCs in which TTF-1 was evaluated on de-stained smears showed nuclear positivity. Histopathology was available in two SCCs and showed morphology similar to FNAC. CONCLUSION: Cytology plays an important role in the diagnosis of GB-NETs for appropriate subtype characterization, which is necessary for the prognostication of these tumours. TTF-1 may not be used for the differentiation of gallbladder SCCs from pulmonary SCCs.

Fine needle aspiration cytology features of poorly differentiated thyroid carcinoma.

BACKGROUND: Poorly differentiated thyroid carcinoma (PDTC) is an uncommon thyroid malignancy with biological behaviour intermediate between well-differentiated and undifferentiated thyroid carcinoma. The cytological diagnosis of PDTC is often difficult as a result of a lack of well-established cytomorphological features and a considerable degree of morphological overlap with other commoner thyroid neoplasms. OBJECTIVE: To review the cytomorphological features of PDTC with the aim of highlighting salient diagnostic morphological features and differential diagnostic problems. METHODS: Seven cases of histologically proven PDTC with available aspiration cytology smears were reviewed for the presence of distinguishing cytomorphological features. RESULTS: The architectural arrangement of tumour cells was the most important diagnostic parameter. Cellular nests, three-dimensional clusters dyscohesive aggregates and singly dispersed cells in the background were present in all cases. A unique 'garlanded appearance', owing to the peripheral orientation of nuclei within the tumour cell clusters, was noted (71.4%) along with the presence of basement membrane-like material (71.4%). Transgressing vessels (85.7%) and endothelial wrapping of cell clusters (71.4%) were also noted. Interestingly, most cases lacked necrosis and mitotic activity that are included in the histological diagnostic criteria for PDTC. CONCLUSION: Although PDTC has considerable cytomorphological overlap with well-differentiated thyroid tumours, this present study highlights certain cytomorphological features that may suggest the correct pre-operative diagnosis, important for the appropriate management.

Differentiation of histoplasma and cryptococcus in cytology smears: a diagnostic dilemma in severely necrotic cases.

OBJECTIVE: The correct identification of fungal organisms is important for the appropriate clinical management of patients. It becomes difficult in necrotic smears when the tissue response is not clearly discernible. It is difficult to distinguish between histoplasma and cryptococcus in severely necrotic cases, where both appear as variably sized clear refractile haloes. METHODS: Four cases of adrenal necrotic histoplasma infection were studied and the morphology was compared with that of non-necrotic histoplasmosis and cases of cryptococcal infection. Eleven cases were analysed in fine needle aspiration cytology (FNAC) smears. Ziehl-Neelsen (ZN) stain was performed to exclude tuberculosis in necrotic smears. A clinical and serology correlation was performed where available. RESULTS: Necrotic cases of histoplasma infection revealed negative refractile clear haloes similar to those of cryptococcus. Histoplasma showed methylene blue-stained organisms in ZN stains, whereas the cryptococcus cases were negative. Similar methylene blue-stained organisms were seen in non-necrotic histoplasma infection. CONCLUSION: As a result of morphological overlap between cryptococcus and histoplasma, the distinction between the two fungi can be difficult in many cases. ZN staining appears to have a role in the differentiation of these fungi in severely necrotic cases. This observation needs to be validated on a larger number of cases with complete correlation with clinical, serology and treatment records.

Cell blocks in cytopathology: a review of preparative methods, utility in diagnosis and role in ancillary studies.

The cell block (CB) is a routine procedure in cytopathology that has gained importance because of its pivotal role in diagnosis and ancillary studies. There is no precise review in the published literature that deals with the various methods of preparation of CB, its utility in diagnosis, immunocytochemistry (ICC) or molecular testing, and its drawbacks. An extensive literature search on CB in cytology using internet search engines was performed for this review employing the following keywords: cell block, cytoblock, cytology, cytopathology, methods, preparation, fixatives, diagnostic yield, ancillary and molecular studies. Ever since its introduction more than a century ago, the CB technique has undergone numerous modifications to improve the quality of the procedure; however, the overall principle remains the same in each method. CBs can be prepared from virtually all varieties of cytological samples. In today's era of personalized medicine, cytological specimens, including CBs, augment the utility of cytological samples in analysing the molecular alterations as effectively as surgical biopsies or resection specimens. With the availability of molecular targeted therapy for many cancers, a large number of recent studies have used cytological material or CBs for molecular characterization. The various techniques of CB preparation with different fixatives, their advantages and limitations, and issues of diagnostic yield are discussed in this review.

Utility and pattern of positivity of p40 in the diagnosis of squamous cell carcinoma of the lung by cytology: the first study on fine needle aspiration smears.

OBJECTIVE: Immunohistochemistry for p40 has emerged as a clinically applicable tool with high sensitivity and specificity to distinguish lung adenocarcinoma and squamous cell carcinoma (SCC). It appears to be an excellent marker for squamous differentiation. Although application of p40 in cell blocks has been reported, its expression has not been described in cytology smears. The aim was to study the expression of p40 in fine needle aspirates of SCC of the lung and to analyse differences in immunoreactivity in variably differentiated SCC. METHODS: The study used aspirates of lung masses diagnosed as SCC over a period of 2 years. p40 immunocytochemistry was performed on destained Papanicolaou smears. Nuclear staining was semi-quantitatively evaluated as 0, 1 + , 2 +  and 3 +  based on the percentage positivity of tumour cells and was correlated with differentiation of the tumour. Adequate unmatched histology (50 biopsies) and cytology (25 smears) controls were taken for comparison. RESULTS: A total of 45 cases of primary and five cases of metastatic pulmonary SCC were identified. There were 17 well, 24 moderately and nine poorly differentiated SCC. p40 immunoreactivity was 2-3 +  in all moderate and poorly differentiated tumours, however, negative to 1 +  in all well-differentiated carcinomas (P < 0.0001). CONCLUSION: p40 immunostain is a valuable stain in identifying lung SCCs and works well in aspiration smears. The pattern of positivity varies with the differentiation of the tumour and is seen prominently in higher grade SCC where in practice the need arises for distinguishing them from either poorly differentiated adenocarcinomas or non-small cell carcinoma, not otherwise specified.

Fine needle aspiration cytology of medullary carcinoma of the thyroid with a focus on rare variants: a review of 78 cases.

BACKGROUND: The cytological features of variants of medullary carcinoma of the thyroid (MCT) are sparsely documented in the literature from case reports. Detailed cytomorphological analysis of MCT variants and features helping to distinguish them from usual MCT are presented here. MATERIALS AND METHODS: A total of 78 aspirates with a diagnosis of MCT over a period of 10 years were re-evaluated. Cytomorphological details were reviewed and semiquantitatively analysed. Histology slides were reviewed in 36 cases. RESULTS: Most aspirates showed classical features of dispersed polygonal or plasmacytoid cells with areas of spindling. In 54 aspirates, a definite cytological diagnosis of medullary carcinoma was made, which in 87.1% was based on cytomorphology alone and in 12.9% was based on immunocytochemistry for calcitonin. In 30.1% of aspirates from MCT, a guarded report of tumour was given in the absence of calcitonin immunocytochemistry. Of the 78 cases, nuclear grooves were seen in 5.1%, intranuclear cytoplasmic inclusions in 28.2%, cytoplasmic granularity in 23.1% and bizarre cells with abrupt anisocytosis in 85.9%. A follicular arrangement was seen in 14.1% and was more frequent in the follicular type (one case) and mixed follicular and medullary carcinoma (one case). Melanin production was seen in aspirates from two cases. One case of the giant cell type of MCT was seen, in which background cells showed large pleomorphic nuclei and numerous bizarre tumour giant cells, prompting a differential diagnosis with anaplastic carcinoma. One example each of the small cell type, paraganglioma-like MCT and papillary MCT were seen. CONCLUSIONS: MCT has uniform cytological features in the majority of aspirates, including many of the histological variants. Searching for pigment in every aspirate of MCT may be rewarding. The giant cell type of MCT is rare and has to be differentiated from anaplastic carcinoma.

Cytopathological diagnosis of alveolar soft part sarcoma, a rare soft tissue neoplasm.

OBJECTIVE: Alveolar soft part sarcoma (ASPS) is a rare soft tissue neoplasm, having various morphological mimics, especially on fine needle aspiration cytology (FNAC). Because no definite immunohistochemical markers are available to aid a correct diagnosis, knowledge of the cytomorphological features is essential for correct patient management. Cytological features of five cases of ASPS are discussed, along with the ultrastructural findings available in one of them. METHODS: Cytology records from 1997 to 2009 were reviewed for cases with a diagnosis of ASPS on cytology. The histology slides of the cases were also assessed for confirmation of the diagnosis. All the slides were reviewed by three pathologists. RESULTS: There were five cases of ASPS diagnosed on FNAC. Their cytological features were noted in detail. The diagnoses in all the cases were confirmed on histology, and ultrastructural findings available in one of them were also assessed. CONCLUSIONS: The knowledge of cytological features may aid in diagnosing this rare tumour correctly on FNA smears, thus enabling correct patient management.

Anaplastic large cell lymphoma: a critical evaluation of cytomorphological features in seven cases.

OBJECTIVE: Anaplastic large cell lymphoma (ALCL) is a rare subtype of non-Hodgkin's lymphoma that is difficult to diagnose on fine needle aspiration cytology (FNAC). Detailed descriptions about the cytomorphological features of ALCL are few and do not illustrate the various categories of cells, which we have done in this study. METHODS: Eight FNAC specimens from seven patients with biopsy-proven ALCL over a period of 6 years were reviewed. Cytomorphological details were analysed and the various cell types identified were enumerated on Papanicolaou and May-Grünwald-Giemsa (MGG)-stained smears. RESULTS: Of the seven cases, five were of conventional type, one of the lymphohistiocytic variant and one of the small cell variant. Aspiration from the conventional type showed a mixed population of lymphoid cells with many plasma cells. The tumour cells were intricately admixed within and distributed as single cells without grouping. Distinct hallmark cells, doughnut cells, embryo cells, tennis racket cells, cells with wreath-like nuclei, Reed-Sternberg-like cells and nondescript cells were seen. Nucleoli were rounded, occasionally tubular in shape. The tumour cells showed abundant blue cytoplasm on MGG stain with a perinuclear hoff. Aspiration from the lymphohistiocytic and small cell variants showed a small number of similar characteristic giant cells. All cases were confirmed as ALK-1 positive. CONCLUSIONS: The morphological spectrum of ALCL is wide and it may be misdiagnosed as a metastatic poorly differentiated malignant tumour on FNAC. Identification of unusual giant cells on FNAC helps in establishing a diagnosis on an early lymph node biopsy.