Factors affecting the differential epithelial cell count in preputial cytology of healthy intact dogs.

Information is limited on the factors that may affect the preputial differential epithelial cell count in healthy intact dogs. Our objectives were to establish RIs of the preputial differential epithelial cell count in dogs and investigate the potential impact of signalment, presence of gross preputial discharge or neutrophils, preputial cleaning, and normal estrogen variation on the differential cell count. We enrolled prospectively 50 client-owned, healthy dogs in our study. Preputial cytology smears were obtained, and we performed a 4-part (parabasal, intermediate, superficial, cornified) differential cell count, before and after gentle preputial cleaning. We found higher counts of fully cornified cells (median: 11-12%) compared to previous studies. The cleaning procedure significantly decreased the intermediate (p = 0.002) and increased the superficial (p = 0.006) cells. Age was positively associated with intermediate (p = 0.007) and negatively with superficial (p = 0.01) and cornified (p = 0.02) cells. The concentration of estrogens was negatively associated with the percentage of parabasal cells (p = 0.04). In healthy dogs, a variable impact may be expected in the preputial differential epithelial cell count, by the cleaning of the prepuce before sampling, the age of the dogs, and the normal variation of estrogen concentration.

An immersive simulation strategy to teach canine vaginal cytology: A multi-centre study.

Vaginal cytology (VC) is an essential technique for monitoring the bitch's estrus cycle. Currently, animal-free teaching methodologies have not been investigated for VC. Hence, this study aimed to evaluate an immersive simulation with a VC model and augmented reality tools. Students (n = 219) from four universities were enrolled, having learning stations with models for practising VC that provided immediate feedback on the technique. Augmented reality tools comprised QR codes that endorsed students to short videos of owners' avatars reporting the clinical reproductive story of the simulated animals and slides with QR codes leading to microscopy slide navigation videos. Proestrus, estrus, diestrus, anestrus and vaginitis were identified in the learning stations. The students' perceptions were evaluated through questionnaires assessing satisfaction, motivation, confidence, impact on learning and diagnostic accuracy. Before the immersive simulation, students had no experience with VC, being afraid of doing a VC with a live dog. Almost all the students considered practicing VC as essential and 94% reported that repeating the procedure (>2 times) was the most important parameter for learning. The simulation activity lasted ≈3 h and significantly improved the confidence of students, being less afraid of doing a VC in a live animal. Slide navigation videos improved the diagnostic accuracy of the estrus cycle stage, and students diagnosed the estrus and vaginitis cases more accurately. The immersive simulation strategy allowed repeated practice in a safe, motivated and standardized environment, being appraised by students as an essential strategy for learning VC.

An immersive simulation strategy to teach cytology sample collection methods and basic diagnosis skills: A two academic center study.

BACKGROUND: Collecting cytology samples and making simple diagnoses are skills taught in veterinary universities, mostly in a passive way. Simulators enhance practical skills learning, increasing student engagement through immersive activities. These strategies have not been carefully assessed in veterinary cytology. OBJECTIVES: This study aimed to describe a simulator developed for training cytology sample collection methods and assess the utility of an immersive simulation strategy to learn and practice the collection of cytology samples. METHODS: A flipped classroom with a station design was followed. Students first watched video tutorials on sampling collection, listened to brief cases' clinical histories, and moved to immersive simulator stations. There, they practiced imprints, swabs, and fine-needle aspiration (FNA). Microscopic observation of the material was available through augmented reality tools. Students were evaluated by Objective Structured Clinical Examination (OSCE) tools on their ability to perform FNA on stuffed animal models. Students answered two questionnaires addressing their learning outcomes. RESULTS: Second- and third-year students from two centers (n = 129) practiced cytologic collection methods in simulators which significantly changed their willingness to perform FNA in live animals after the class activities. OSCE pass rates over 90% were obtained for most steps of FNA, and students rated the activity as essential/very relevant for learning. CONCLUSIONS: Immersive simulation strategies were effective at increasing student comfort with cytologic sampling techniques. This approach should be included in the veterinary curriculum as it can increase the quality of cytology samples and could potentially improve the cytologic diagnosis of a submitted sample.

CSF from a puppy with a cerebral vascular hamartoma.

A 9-week-old puppy with refractory seizures and a dome-shaped head presented to the Mississippi State College of Veterinary Medicine Specialty Center for suspected hydrocephalus. Computerized tomography (CT) findings included transtentorial herniation and an intra-axial mass with dystrophic mineralization. Cerebrospinal fluid analysis revealed an increased nucleated cell count of 1100/µl (RI < 5/µl), erythrocyte count of 2.2 × 106 /µl, and markedly increased microprotein of 1939 mg/dl (RI < 30 mg/dl). On cytologic examination of the CSF, numerous erythrophagocytic, and hemosiderin-laden macrophages were observed, which indicated chronic active hemorrhage. Many neutrophils, macrophages, and lymphocytes that contained numerous intracytoplasmic, pleomorphic, bright yellow crystals were observed. Considering the ongoing hemorrhage, the crystals were presumed to be hematoidin. A biopsy with histopathology was performed on the intra-axial mass, and the results were consistent with a vascular hamartoma. We speculate that the formation of these crystals was related to the ongoing hemorrhage associated with the vascular hamartoma. Identification of these crystals may be useful to aid in the identification of chronic hemorrhage associated with vascular malformations or lesions within the central nervous system.

Usefulness of squash preparation cytology in the diagnosis of canine urinary bladder carcinomas.

BACKGROUND: Epithelial cells show varying degrees of cytologic atypia in dogs with nonmalignant lesions (NML) and carcinomas (ubC) of the bladder, making histopathologic examination necessary for a definitive diagnosis. OBJECTIVES: This study aimed to investigate the diagnostic performance of squash preparation cytology and identify several cytomorphologic features of ubC to assist in diagnoses. METHODS: Squash preparations were made and reviewed in dogs that underwent transurethral cystoscopy. The results were compared with histopathologic diagnoses. Two cytopathologists performed blinded assessments using a scoring system established for 11 cytologic features, including the presence of macronuclei, abnormal nucleoli, atypical mitoses, signet ring cells, multinucleated cells, nuclear molding, anisokaryosis, cytoplasmatic microvacuolization, cell arrangements, and neutrophil and lymphocyte infiltrations. Based on cytologic and histopathologic diagnoses, dogs were divided into ubC and NML groups. Associations between cytologic and histopathologic diagnoses were investigated, and agreement between the cytopathologists was calculated. Cytologic features were analyzed with multivariate logistic regression models. The performance of predictors in the final model was evaluated in terms of Sensitivity (Se), Specificity (Sp), accuracy, positive predictive value (PPV), negative predictive value (NPV), likelihood ratio positive (LR+), and negative (LR-) values, and the diagnostic odds ratio (DOR). RESULTS: Forty-four dogs diagnosed with ubC, and 17 with NML were included in the study. Cytologic and histopathologic diagnoses were significantly associated with each cytopathologist. There was an almost perfect agreement between cytopathologists (κ = 0.88). The absence of neutrophilic infiltration, the presence of multinucleated cells, and nuclear molding were associated with ubC; using a combination of these features in parallel testing resulted in Se = 0.98, Sp = 0.65, accuracy = 0.89, PPV = 0.88, NPV = 0.92, LR + =2.77, LR- = 0.04, and DOR = 7.7. CONCLUSIONS: Squash preparation cytology could be a reliable technique to diagnose ubC in dogs. The best diagnostic combination was the absence of neutrophilic infiltration, multinucleated cells, and nuclear molding.

Diagnostic accuracy of cytology for the detection of bacterial infection in fluid samples from veterinary patients.

BACKGROUND: Bacterial sepsis is a relatively common, life-threatening condition with a high case fatality rate. The current primary diagnostic tools for detecting bacterial infection in fluids are bacterial culture and fluid cytology. While culture is the gold standard, it can take up to several days for results to be made available to clinicians, which can delay recognition of bacterial sepsis and negatively impact patient outcomes. OBJECTIVES: The aim of this study was to evaluate the diagnostic accuracy of cytology for detecting bacterial infection in body fluids. METHODS: We retrospectively reviewed 10 years of medical records at the Ohio State University's Veterinary Medical Center for mammalian patients with both cytology and bacterial culture of fluid samples, including body cavity fluids (abdominal and thoracic effusion), blood, joint fluid, and CSF. The overall sensitivity and specificity of cytology relative to the reference method of bacterial culture was recorded, as well as among the subcategories of fluid type. RESULTS: The overall sensitivity and specificity of cytology for the diagnosis of sepsis were 42.6% and 93.0%, respectively. Individual sensitivities and specificities were also calculated for each fluid type. Thoracic fluid cytology had relatively high sensitivity and low specificity, in contrast to the other fluid types analyzed. CONCLUSIONS: Overall, cytology is poorly sensitive but highly specific for the detection of bacterial infection in fluid samples. The results from this study will allow a better comparison between the diagnostic accuracy of cytology and emerging diagnostic tests for the detection of bacterial sepsis in mammalian patients.

A comparison of cytologic quality in fine-needle specimens obtained with and without aspiration from superficial lymph nodes in the dog.

OBJECTIVES: To assess the impact of aspiration on cytologic quality of fine-needle specimens obtained from lymph nodes of dogs and to compare the level of agreement of the cytologic diagnosis between the two sampling techniques. MATERIALS AND METHODS: Fifty-three client-owned dogs were prospectively enrolled. Client-owned dogs were prospectively enrolled in the study if cytologic examination of lymph nodes was indicated in the course of their clinical diagnostic work-up. In each dog, two superficial, palpably accessible lymph nodes were sampled: one by fine-needle aspiration and the other by fine-needle non-aspiration, using a 21-Gauge needle with or without a 5-mL syringe. Cytologic quality was assessed in duplicate smears assessed by two observers who rated cellularity, blood contamination, thickness, cell preservation and cytoplasmic fragmentation using a predefined scoring system. RESULTS: Fifty-three client-owned dogs were included in the study. No significant difference was found in rating scores between the two sampling techniques for any of the cytologic quality parameters assessed. Cohen's kappa coefficient was 0.84 (95% confidence interval 0.68-1.00), indicating diagnostic agreement between the sampling techniques. CLINICAL SIGNIFICANCE: In this study, both fine-needle aspiration and fine-needle non-aspiration techniques yielded lymph node specimens of comparable cytologic quality and with acceptable agreement in cytologic diagnosis.

Canine mast cell tumors: utility of stereologic tools in cytology.

Quantitative morphologic parameters assessed in cytologic samples of canine cutaneous mast cell tumors (ccMCTs) may assist with surgical planning and prognostication. Robust cutoffs can be defined, with high reproducibility, for parameters such as the nuclear area (NA). The NA may be determined by morphometry (image analysis, NAI) or by stereology, such as the 2D-nucleator method (NAN); stereologic techniques have not been applied to cytologic specimens of ccMCT, to our knowledge. We retrospectively selected routine cytology smears from 51 ccMCT cases and screened them to determine the percentage of neoplastic mast cells with indistinct nuclear borders; this was repeated after the slides were restained with H&E. The NAI and the NAN were estimated in 100 mast cells per animal in H&E-stained slides. All nuclei were visible in H&E smears, and unbiased quantification was feasible. The NAN was similar to NAI, but less time-consuming. Both the NAN and NAI determined by cytology differed in histologic low- and high-grade ccMCTs, and in histologic grade I plus II versus grade III ccMCTs. Stereologic parameters such as the NAN could be considered as complementary techniques for the cytologic evaluation of ccMCTs.

A reliable method using the cytobrush for diagnosis of subclinical endometritis in dairy cattle during the late lactational period.

This experiment was performed to assess reliability of the cytobrush-cytology method (CCM) in diagnosis of subclinical endometritis (SCE) using the biopsy-histopathology method (BHM) as a reference in late lactating dairy cows. Reproductive organs were collected from 115 slaughtered multiparous crossbred cows culled due to infertility 398 ± 135 days subsequent to parturition. Samples were collected from the dorsal part of the corpus uteri for analyses. Inflammation status was graded histopathologically based on the cell percentages [(neutrophils, eosinophils, lymphocytes (LYM), macrophages (MAC), and plasma cells)]. Data were subjected to Friedman's test for group comparisons (method and diagnosis), concordance correlation and chi-square tests for consistency of results among methods, and the receiver operating characteristics curve analysis for reliability of the CCM. Percentages of LYM (2.67x) and MAC (3.00x) were greater when evaluated using BHM than with CCM (P < 0.05 for both). The agreement (Cohen's κ value) of results among methods was 0.79 ± 0.06. The sensitivity (Se) and specificity (Sp) of the CCM for defining endometrial inflammation were 79.3% and 100%, respectively. Among inflammatory cells, proportions of LYM and MAC in the CCM had merit for evaluation of uterine inflammation, with an Se of 74.1 and 84.5 and an Sp of 93.0 and 75.4 at the cut-off > 4 and > 0, respectively. The results indicate the CCM may be used in the diagnosis of SCE when the LYM and MAC percentages are considered in chronically infertile cows in the later stages of the lactational period.

An uncommon occurrence of bicavitary effusion due to mast cell neoplasia in a 12-year-old mixed breed dog.

A case of bicavitary effusion affecting a 12-year-old female spayed mixed breed dog that was presented to Tuskegee University College of Veterinary Medicine's Emergency Service for abdominal distension and vomiting. Upon physical exam, the patient exhibited signs of pain and sensitivity to touch and pain on abdominal palpation with a positive fluid wave. The patient also had dull mentation and increased respiratory effort with an abdominal component. On labwork, there was a leukocytosis characterized by a mature neutrophilia, monocytosis, and basophilia. A mild thrombocytopenia with low numbers of poorly granulated mast cells were also noted on peripheral blood smear review. Serum biochemistry revealed a mild azotemia and abnormal SNAP cPL test. The patient received a full abdominal ultrasound, which detected bicavitary effusion, hepatomegaly, and splenomegaly. Cytology of the cavitary effusions was moderately cellular with significant numbers of mast cells. The patient was euthanized following a tentative diagnosis of systemic mastocytosis. The clinical signs, in this case, are consistent with published data for systemic mastocytosis, which include organomegaly, abdominal pain, gastrointestinal signs, and hematologic abnormalities. However, this is the first report of bicavitary effusion due to presumed systemic mastocytosis.

Correlation between cytologic features and histologic grades in cutaneous and subcutaneous soft tissue sarcomas in dogs-A pilot study.

Currently, canine soft tissue sarcoma (STS) grading is based on histopathology. In humans, several studies have demonstrated concordance between cytologic grading systems for STS and histologic grade. The aim of this study was to correlate several cytologic parameters (smear cellularity, anisokaryosis, nucleolar malignancy score, multinucleation, and the number of mitotic figures per 200 cells) that form part of a human STS cytologic grading system, with histologic grades of canine cutaneous and subcutaneous STS. Three observers (blinded) reviewed the cytologic preparations independently from cases with confirmed histologic diagnoses of STS. A cytologic grading score was assigned for each parameter. Correlations between cytologic grading scores (averaged between observers) and histologic grades were assessed using Spearman's correlation coefficient, with statistical significance defined as P < .05. Twenty-one cases were included in the study (10 Grade I STS, nine Grade II STS, and two Grade III STS). The number of mitotic figures (≥3) per 200 cells was the only parameter that showed a significant but weak, positive correlation with histologic grade (rs  = .469; P = .032). No Grade I tumors had ≥3 mitotic figures per 200 cells; however, ≥3 mitotic figures per 200 cells were only observed in 33% of Grade II tumors and 50% (one out of two) of the Grade III tumors. This pilot study suggests that an increased number of mitotic figures seen on cytology might correlate with higher grade STS; however, the sensitivity of this parameter for grading STS appears to be low.

Cytology of Feline Nodal Lymphoma: Low Interobserver Agreement and Variable Accuracy in Immunophenotype Prediction.

Nodal lymphomas are less common in cats than in dogs and, consequently, no specific studies have been published. Cytology is the first step in the diagnosis of nodal lymphoma but is highly subjective. Morphological features have been introduced for the cytological classification of canine lymphomas but not for cats. Therefore, the aim of this study was to evaluate interobserver agreement on various cytological features of feline nodal lymphomas and to investigate the accuracy in predicting B or T immunophenotypes. Four veterinary cytologists examined 25 feline nodal and mediastinal lymphoma cytological samples by adapting the criteria used for the evaluation of canine lymphomas and setting histopathology and immunohistochemistry as the gold standard. High interobserver variability was found in the evaluation of most features except for the presence or absence of cytoplasmic vacuoles, which were more common in B-cell lymphomas. Cytology training centre was the major factor influencing the extent of agreement among evaluators. Diagnostic accuracy in predicting lymphoma immunophenotype varied from 35% to 75% and did not appear to be correlated with the experience of the evaluators. We conclude that cytological criteria, commonly used to describe canine lymphomas, are not adaptable to the counterpart feline neoplasms. Cytology-based immunophenotyping of feline lymphomas from different laboratories, and different cytologists within the same laboratory, differ substantially and should not be considered reliable. Specific cytological criteria are needed to describe feline lymphoma.

Cytobrushing of the oral mucosa as a possible tool for early detection of testudinid herpesvirus in Horsfield's tortoises with nonspecific clinical signs.

Forty-five Horsfield's tortoises (Testudo horsfieldii; syn. Agrionemys horfieldii, Russian tortoise) belonging to different owners had decreased appetite and respiratory issues. Twenty-nine tortoises had epiphora, dyspnea, and white necrotic diphtheroid oral plaques (group G1). Ten of the remaining 16 tortoises had serious dehydration, appetite disorder, and depression (G2). The last 6 tortoises had only decreased appetite and moderate conjunctival discharge (G3). During the physical examination of all 45 tortoises, a cytologic sample and an oral swab for herpesvirus and Mycoplasma agassizii PCR testing were taken. In 20 of 29 specimens from G1, in 8 of 16 from G2, and 0 of 6 from G3, the cytologic exam revealed intranuclear acidophilic inclusion bodies, multinucleate cellular syncytia, and further abnormalities caused by herpesviral infection. Moreover, all 45 tested subjects were found to be positive for testudinid herpesvirus 1; 2 were positive for M. agassizii. This prospective study suggests that Horsfield's tortoises with such signs would benefit from this screening procedure, given that it was effective in a significant proportion of infected and symptomatic animals, and no negative effects were seen.

Myoepithelial cells and extracellular matrix in the cytologic differentiation of canine mammary tumors.

BACKGROUND: Mammary neoplasms are common tumors in intact female dogs. Fine-needle aspiration cytology (FNAC) is a valuable diagnostic tool and has gained some credibility in the diagnosis of mammary tumors in dogs. Prompt classification of canine mammary tumors using cytology would enhance feasibility as a prognostic tool and guide clinical and surgical management. OBJECTIVES: We aimed to examine background elements to differentiate mammary tumors using FNAC. We proposed to distinguish simple from complex and mixed tumors by identifying myoepithelial (ME) cells and different types of extracellular matrix. Additionally, we determined the accuracy of FNAC to differentiate benign from malignant tumors. METHODS: One hundred and one mammary tumors from female dogs were included in this study. We compared FNAC using histopathology as the gold standard. Cellular and background components were evaluated and identified. The cytologic accuracy, sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) for diagnosing malignancy were determined, excluding inadequate samples. RESULTS: The cytologic-histologic agreement was 92.5% for simple carcinomas, 57.9% for complex-type carcinomas, 57.1% for mixed-type carcinomas, 27.3% for carcinosarcomas, and 100% for osteosarcomas. Myoepithelial cells were successfully identified using FNAC. Myxoid and chondroid/osteoid matrix were satisfactorily recognized. Cytologic accuracy, Se, Sp, PPV, and NPV for diagnosing malignancy were 99%, 100%, 83%, 99%, and 100%, respectively. CONCLUSIONS: Chondroid/osteoid matrix was noted in mixed tumors but not in complex tumors. Myxoid matrix, often associated with ME cells, was noted in complex and mixed tumors. Mesenchymal cells were differentiated from ME cells, allowing the distinction of simple carcinomas with scirrhous reaction from complex and mixed tumors.

Cytobrush cytology patterns of early postpartum dairy cows.

Endometrial cytobrush cytology has been recommended as a reliable method for determining the percentage of polymorphonuclear leukocytes (PMN%) in cattle smears to diagnose cytological endometritis (CE). In this study, the clarity of cytobrush　cytological smears and the influence of different sample evaluation methods (number　and types of cells counted) on CE diagnosis were evaluated. Samples from 28 lactating　Holstein cows were collected weekly between 3 and 7 weeks postpartum. Smear clarity,　based on cell density, quality of cell morphology, and red blood cell contamination,　was significantly poorer at 3 weeks than between 5 and 7 weeks postpartum. Five　different cell counting methods (C100, C200, C300, C400, and C500) were used,　where 100-500 nucleated cells (endometrial epithelial cells, PMN consisting of neutrophils, eosinophils and basophils, lymphocytes, and macrophages) were counted. Agreement of diagnostic results for CE between C300 and C500 and between C400 and C500 was excellent at all observation times. In calculations of the PMN% based on whether the number of lymphocytes and macrophages were or were not excluded in the denominator, exclusion of these cells in the calculations did not affect the diagnosis of CE. While reduced clarity in earlier stage samples might interfere with the accuracy of cytobrush cytology, C300 can be recommended to determine the endometrial PMN%.

Diagnosis of canine renal lymphoma by cytology and flow cytometry of the urine.

Lymphoma is a common hematopoietic neoplasm of dogs. A definitive diagnosis typically requires the collection of samples via fine-needle aspirate or biopsy. A unique case of canine renal T-cell lymphoma diagnosed using urine sediment microscopy with flow cytometry and PCR for Antigen Receptor Rearrangement (PARR) is presented. A fresh urine sample was collected via a urinary catheter and immediately prepared for cytologic examination, flow cytometry, and PARR. The flow cytometric study revealed that 83% of the cells were large CD3+ CD8+ T cells, while PARR identified a clonally rearranged T-cell receptor gene, supporting the flow cytometry findings. Despite supportive care, the patient progressed to anuric renal failure and was humanely euthanized. A necropsy was performed, and tissues from the upper and lower urinary tracts were collected. Histologically, the right and left kidneys were infiltrated by a neoplastic round cell population effacing the cortex and medulla. Immunohistochemistry for the T- and B-cell antigens CD3 and CD20, respectively, revealed that the neoplastic population within the kidney demonstrated diffuse, strong, membranous to intracytoplasmic CD3 expression while lacking CD20 expression. These results confirmed the diagnosis of renal T-cell lymphoma. This is the first known report of canine lymphoma diagnosed using either urine flow cytometry or clonality testing. Therefore, in select cases, urine flow cytometry and/or PARR are feasible to perform on urine-derived cells as a quick and cost-effective means to aid in the diagnosis of urinary tract lymphoma.

Fine-needle aspiration of cutaneous, subcutaneous, and intracavitary masses in dogs and cats using 22- vs 25-gauge needles.

BACKGROUND: Fine-needle aspiration (FNA) is a common procedure as a diagnostic tool in veterinary medicine. However, it is unclear whether the gauge of the needle affects the quality of cytology. OBJECTIVE: This study compared the quality of cytologic samples obtained via FNA using 22- or 25-gauge needles. METHODS: Fine-needle aspiration was performed on 50 masses (cutaneous, subcutaneous, or intracavitary) obtained from client-owned animals. The size of the needle was randomly assigned using either of the following two sequences: 22-25-22 gauge or 25-22-25 gauge. Samples were evaluated by two board-certified clinical pathologists to assess cellularity, blood contamination, amount of cellular debris, degree of cellular trauma, and the overall ability to make a diagnosis for each sample. RESULTS: No significant difference was detected between the 22- and 25-gauge needle samples for cellularity, whereas a significant difference was present for blood contamination, amount of cellular debris, and degree of cellular trauma. The overall ability to make a diagnosis was not significantly affected by the needle gauge. The degree of cellular trauma was significantly increased in intracavitary samples. CONCLUSIONS AND CLINICAL RELEVANCE: Needle gauge is a contributing factor to FNA sample quality. However, it did not affect the overall ability to make a diagnosis. Samples obtained using 25-gauge needles resulted in less blood contamination yet increased cellular trauma compared to 22-gauge needle samples.

The utility of intraoperative impression smear cytology of intracranial granular cell tumors: Three cases.

Two adult male dogs (a 7-year-old shorthaired Chihuahua and 14-year-old Shih Tzu) and one adult female dog (a 9-year-old Maltese) presented for evaluation of new-onset seizure activity. Magnetic resonance imaging of the brain demonstrated a large, poorly marginated T2-weighted hyperintense, and strong contrast enhancing extra-axial mass in each case. A surgical biopsy for histopathologic evaluation was elected in all cases, and intraoperative impression smears were successfully obtained. Intraoperative cytology identified a homogenous population of round to polygonal cells with central to eccentric nuclei, coarse chromatin, and variably amphophilic to eosinophilic granular cytoplasm. Cytologic findings led to a suspected diagnosis of granular cell tumor (GCT) in all cases. Histopathologic review identified a densely cellular, unencapsulated neoplastic mass comprised of sheets of large round to polygonal cells with abundant eosinophilic cytoplasm containing numerous eosinophilic intracytoplasmic granules, confirming the diagnosis of GCT in all cases. The cases reported here are unique in that they reveal an accurate intraoperative cytologic diagnosis of a rare canine central nervous system neoplasm. Intraoperative cytology of the intracranial masses could provide clinicians with important and quick diagnostic and prognostic information; therefore, expediting decisions made intraoperatively. Further research is warranted to determine the diagnostic accuracy of intraoperative cytology for neoplasia in veterinary patients.

Cytology and the cell block method in diagnostic characterization of canine lymphadenopathy and in the immunophenotyping of nodal lymphoma.

Minimally invasive techniques used to evaluate canine peripheral lymphadenopathy (PLN), including fine needle aspiration biopsy with cytological evaluation (FNAB-C) and flow cytometry (FC), have benefits and limitations. The cell block (CB) method is an alternate processing technique in which fine needle aspirate biopsy samples are concentrated, fixed, and embedded in paraffin for routine histological processing/staining. Utilizing three observers, we determined the diagnostic value of the CB in evaluating canine PLN across six categories (non-diagnostic, reactive, inflammatory/infectious, probable lymphoma and lymphoma, metastatic neoplasia) and correlated findings to immunophenotypic and clonal antigen receptor rearrangement results in canine nodal lymphoma. Eighty-five paired FNAB-C and CB samples were evaluated from canine patients presenting to the University of Minnesota Veterinary Oncology or Internal Medicine services. Diagnostic quality samples were obtained in 55/85 (65%) CB and 81/85 (95%) FNAB-C samples, respectively, and nodal pathology impacted CB diagnostic yield. Overall percent agreement between diagnostic-quality FNAB-C and CB samples was 86%, but increased to 95% if the categories of lymphoma and probable lymphoma were combined. There was 100% agreement for both the diagnoses of metastatic neoplasia and reactive lymph nodes and 92% agreement for the diagnosis of lymphoma/probable lymphoma. Using immunohistochemistry (IHC), CB samples correctly immunophenotyped 22/23 (96%) cases of B-cell lymphoma, but only 1/6 (17%) cases of T-cell lymphoma. IHC was not completed on nine cases of lymphoproliferative disease because of insufficient cellularity. When the CB method (CBM) yielded diagnostic quality samples there was good to excellent agreement with FNAB-C samples and CB samples were suitable for some IHC tests.