Faculty Bibliography

Immunohistochemistry (IHC), also referred to as immunocytochemistry in cytology literature, has revolutionized the practice of cytopathology. Because of the complexity of cytology preparation and limited diagnostic material, performing IHC remains a challenge. Formalin-fixed paraffin-embedded (FFPE) cell block (CB) is the optimal choice for IHC. In this review, the approaches for improving CB preparation will be discussed. When CB material is not available, various cytology specimens can also be used for IHC. With the utilization of Antigen Retrieval (AR) technique, these nonformalin-fixed cytology specimens can achieve successful IHC staining, comparable with the results from FFPE tissue sections. In the last part of this review, we will discuss the use of positive controls and the important role of AR in standardization of IHC in cytology.

Myoepithelial carcinoma (MEC) of soft tissue, also known as malignant myoepithelial tumor, is an uncommon malignancy. Cytologic diagnosis of this entity is challenging due to its rarity and heterogeneous morphology. We report a case of MEC in a 22-year-old man, who presented with a 6.5 cm soft tissue mass on his right distal forearm that has been enlarging over the past 3 months. Ultrasound-guided fine-needle aspiration (FNA) revealed abundant isolated neoplastic cells ranging from spindled cells to epithelioid and plasmacytoid morphology in a myxoid background. These cells showed moderate cytologic atypia characterized by high-nuclear/cytoplasmic ratio, irregular nuclear contours, and prominent nucleoli. The cytoplasm varied from dense to vacuolated and occasionally rhabdoid with intracytoplasmic inclusions. Scattered bi- and multinucleated cells were identified. A diagnosis of high-grade malignancy was made with the differential diagnosis including rhabdomyosarcoma and melanoma. A subsequent core biopsy of the tumor showed immunoreactivity for pan-cytokeratins, calponin, p63, and smooth muscle actin. INI-1 was lost. SOX-10 and Melan-A were negative. Molecular studies showed loss of SMARCB1 (INI-1) and CDKN2A. Gene fusion studies did not detect any fusion. A diagnosis of soft tissue MEC was made which is a challenge on FNA due to several cytologic mimickers including rhabdomyosarcoma, epithelioid sarcoma, extrarenal rhabdoid tumor, extra-axial chordoma and melanoma. Recognition of the biphasic cell population in a myxoid background and a battery of immunohistochemical stains are crucial for accurate diagnosis.

INTRODUCTION/BACKGROUND:The American College of Radiology (ACR) Thyroid Imaging Reporting and Data Systems (TI-RADS) was developed to standardize thyroid ultrasound reports and predict the likelihood of malignancy. In our study, we aimed to correlate indeterminate thyroid fine needle aspiration cytology cases with preceding ultrasound (US) ACR TI-RADS scores and concurrent molecular testing results to examine how well the use of the ACR TI-RADS in our institution predicted which patients with indeterminate cytology might harbor molecular alterations. MATERIALS AND METHODS/METHODS:We performed a retrospective review of thyroid nodules. Patients with US reports that included TI-RADS scores, fine needle aspiration specimens with indeterminate cytology (Bethesda class III-V), and molecular testing results were included. RESULTS:A total of 46 indeterminate cytology cases had had preceding US reports with TI-RADS scores and molecular testing (Bethesda class III, n = 37; Bethesda class IV, n = 6; Bethesda class V, n = 3). Most of the indeterminate cases had had a TI-RADS score of TR4 (31 of 46; 67.39%) or TR5 (9 of 46; 19.57%). RAS mutations were the most common alteration (n = 12). Of the 46 cases, 22 (47.85%) showed no alterations. Ten cases proceeded to surgery, of which seven displayed malignancies. CONCLUSIONS:Molecular testing in cytologically indeterminate thyroid nodules provided valuable information for TR4 and TR5 lesions; however, the TR2 and TR3 lesions often had no molecular alterations. These findings highlight the potential value of including US imaging features when assessing the significance of indeterminate cytology findings.

BACKGROUND:Ultrasound has become the initial approach to evaluating thyroid nodules, facilitating the distinction between benign and malignant nodules based on composition, echogenicity, nodule border or margin, shape, the presence of calcifications, and nodule dimensions. The American College of Radiology (ACR) recommended the Thyroid Imaging Reporting and Data System (TI-RADS) as a classification system to standardize thyroid ultrasound reports and to predict the probability of malignancy in thyroid nodules using a scoring system (TR1-TR5) based on multiple ultrasound characteristics and nodule size. Fine-needle aspiration (FNA) is recommended as the next step for nodules that warrant further workup. The authors assessed the accuracy of the ACR TI-RADS based on the corresponding FNA cytology results (Bethesda system diagnoses I-VI). METHODS:ACR TI-RADS ultrasound reports and corresponding FNA cytology diagnoses from January 1, 2018 to August 30, 2018 were evaluated. RESULTS:From January 1, 2018 to August 30, 2018, 2306 thyroid ultrasound-guided FNAs were performed at our institution. Of 2306 cases, 361 had ACR TI-RADS reports available. The majority of FNAs were TR4 (180; 49.9%) or TR3 (108; 29.9%). No TR2 or TR3 nodules were associated with Bethesda category V or VI diagnoses. The majority of TR4 nodules (142 of 180; 78.9%) and TR5 nodules (42 of 65; 64.6%) exhibited benign (Bethesda category II) cytology. Fourteen TR5 cases (21.5%) had malignant (Bethesda category VI) cytology. CONCLUSIONS:Although there were no TR2 or TR3 malignant (Bethesda category VI) diagnoses, and there were only a few malignancies in the TR4 and TR5 categories, the current results reassert the notion that the ACR TI-RADS scoring system shows at least some correlation between benign or malignant cytology diagnoses, as illustrated by the greater number of malignant cases in the higher ACR TI-RADS categories.

BACKGROUND:Differentiating parathyroid from thyroid lesions can be difficult on fine-needle aspiration (FNA) due to overlapping cytomorphologic features. While the traditional parathyroid hormone (PTH) assays can help in the distinction, these tests may be cumbersome, particularly when the lesion is unexpected clinically and a needle wash is not collected at the time of FNA. Therefore, we chose to investigate the application of immunohistochemical staining (IHC) with GATA 3 and thyroid transcription factor-1 (TTF-1) on air-dried cytology smears to distinguish parathyroid and thyroid lesions. METHODS:Air-dried touch preparation (TP) slides were prepared from consecutively selected parathyroid and thyroid specimens. Thirteen FNA cases with the clinical concern for parathyroid lesions were also included in the study. IHC was performed on unstained and ultrafast Papanicolaou (UFP) stained air-dried slides. RESULTS:On TP slides, GATA 3 expression was observed in all cases of parathyroid origin but no immunoreactivity was present in thyroid lesions. TTF-1 expression was observed in all cases of thyroid origin but not in parathyroid lesions. GATA 3 and TTF-1 expression of 13 FNA cases were consistent with the clinical impression or concurrent PTH tests. CONCLUSIONS:IHC with GATA 3 and TTF-1 on air-dried cytology smears is a simple and effective way to differentiate parathyroid vs thyroid lesions on FNA. Air-dried unstained and UFP-stained slides perform equally well with IHC, but UFP-stained slides provide the added benefit of morphologic evaluation and assessment of smear cellularity prior to IHC.

Fine-needle aspiration biopsies (FNABs) are a common modality used in the evaluation of salivary gland neoplasms. We present the cytologic and histologic features of a rare case of lymphoepithelioma-like carcinoma (LELC) in a 40-year-old Hispanic male with a 1.0-cm painless well-circumscribed parotid mass that had been present for 8 years. FNAB smears showed cohesive groups of intermediate-sized basaloid cells with vesicular nuclei, occasional pleomorphic nuclei and prominent nucleoli, and spindled morphology. Mature lymphocytes were seen in the background, either adjacent to the atypical epithelial cells or dispersed in the background. This lymphoid background raises considerations of salivary gland neoplasms that can have prominent lymphocytic backgrounds, such as acinic cell carcinoma and, more commonly, Warthin's tumor or metastasis involving intraparotid lymph node. Surgical resection of the parotid showed syncytial sheets of predominantly undifferentiated cells with spindled to epithelioid morphology and occasional prominent nucleoli and focal areas of squamous differentiation. The background showed dense areas of lymphocytes with germinal center formation. Immunohistochemical (IHC) stains showed positive reactivity for p63, p40, and EBV in situ hybridization (EBV ISH) in the tumor cells and negative reactivity for p16. The findings were supportive of LELC if a metastasis from the nasopharynx was excluded. A subsequent nasopharyngeal biopsy was benign. Although histologic features of LELC are well established, we identified rare case reports describing the cytomorphology in the literature. Cytopathologists should be aware of this lesion as another salivary gland neoplasm that can show lymphocytes admixed with the tumor cells and a distinct lymphoid background. The basaloid appearance and cytologic atypia should distinguish it from acinic cell carcinoma and Warthin's tumor. However, metastatic lesions should also be considered with a distinct lymphoid background and need to be clinically excluded before establishing the diagnosis of LELC

Introduction: TBS diagnostic category rates, ASCUS/(+)hrHPV (high risk HPV) ratio, and cytotechnologist's (CT'S) concordance with the CP's final diagnosis are used as common quality monitors in gyn cytology. Additionally, extending monitoring of the hrHPV (+) rate to NILM and SIL cases has been proposed as quality indicators for cytopathologist's (CP's) performance. At our institution, Pap tests are finalized without the knowledge of hrHPV status. We investigated the impact of known hrHPV status on CPs' interpretation of cases previously screened as NILM, and stipulated its potential consequence on quality metrics. Material(s) and Method(s): 60 Pap tests previously resulted as NILM, half hrHPV (+) and half hrHPV (-), were reviewed blindly by 5 CPs in two rounds at 4 months interval. At first round, correct hrHPV results were provided to the CPs. At second round, incorrect (reversed) hrHPV results were given. McNemar chi-squared test was used to analyze the impact of knowing the hrHPV test result on Pap test interpretation. Kappa coefficient was calculated to test intra-observer agreement between the first and second review of the same slides for each CP. Result(s): ASCUS (13%) was the most upgraded diagnosis followed by 12 LSILs (2%) and 2 HSILs (0.3%). There were no significant differences in Pap test interpretation based on hrHPV status for 3 CPs and marked differences for 2 CPs (Table 1). Intra-observer agreement between round 1 and round 2 diagnoses varied from moderate to poor (Table 2). Conclusion(s): Knowledge of hrHPV status significantly biases some but not all CPs. hrHPV (+) to NILM, ASCUS and SIL ratios may not be the most objective parameters for evaluation of CP performance under these circumstances. This bias has further implications for CT performance evaluation because it impacts CT discordance rate measured against CPs final diagnosis. [Figure presented] [Figure presented]

Introduction: The Thyroid Imaging Reporting and Data System (TI-RADS) was designed to standardize risk stratification of thyroid nodules by ultrasonographic criteria and categorize nodules as TR1-TR5 to designate nodules for fine needle aspiration (FNA) or surveillance. Thyroid FNAs are classified according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) (categories TBS I-VI) with an associated risk of malignancy and management guideline. We utilize Thyroseq-V3 molecular testing for indeterminate cytology cases (TBS III- V). Our aim was to correlate indeterminate thyroid FNAs with TI-RADS scores and molecular results to determine if TI-RADS is accurately identifying nodules for biopsy.
Material(s) and Method(s): A retrospective review of thyroid nodules from 1/1/2018-8/30/2018 was performed. Patients with ultrasound (US) reports including TI-RADS scores, FNA reports with indeterminate cytology (TBS-III, TBS-IV and TBS-V) and molecular testing were included.
Result(s): 370 of 1000 thyroid nodules had US reports with TI-RADS scoring and concurrent cytology. 47 cases had indeterminate cytology (TBS-III n=37, TBS-IV n=7 and TBS-V n=3) and reflex molecular testing. Majority were TR4 (31/47;65.97%) and TR5 (10/47;21.27%) (Table1). 23/47 (48.94%) showed no alteration. NRAS was the most common alteration (8 cases), followed by Copy Number Alterations (CNA) (6 cases) (Figure 1). Three TBS-III cases showed dual alterations (NRAS/CNA x2 and HRAS/CNA). Two TBS-IV cases had multiple alterations (EIF1AX/NRAS/TP53 and NRAS/PTEN).
Conclusion(s): While majority of thyroid nodules had a high TI-RADS score (TR4 or TR5), most cases fell into the atypical category (TBS III). Almost half of the thyroid nodules lacked any molecular alterations thereby suggesting an over-classification by TI-RADS. Further refinement of the TI-RADS criteria may be warranted. [Figure presented] [Figure presented]
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