Use of the argyrophilic nucleolar region method for cytologic and histologic examination of the lymph nodes in dogs

Cutaneous Canine Mast Cell Tumor: The Use of Proliferative Markers (Ki-67 and Ki-67 × AgNOR) in Cytological Samples for Diagnosis and Prognosis

A cytological grading system for canine mast cell tumors (MCTs) has been developed, but its integration into clinical routine has been hindered due to its diagnostic limitations. The aim of this study was to assess the prognostic value of Ki-67 and argyrophilic nucleolar organizing region (AgNOR) markers in cytological MCT samples and to determine cut-off values for these markers in correlation with histopathological grading. Cytological samples were collected prior to surgical excision, and histopathological samples were obtained postsurgery from 45 dogs diagnosed with cutaneous mast cell tumors (MCTs). The cytological specimens were classified using a two-tier grading system, and their Ki-67 (average immunopositive nuclei per 100 cells) and AgNOR (average AgNOR counts per 100 nuclei) signaling was assessed. Through receiver operating characteristic (ROC) analysis, cut-off values for Ki-67 and Ki-67 × AgNOR were determined to better align with histopathological grading (classified as low or high grade according to Kiupel's scoring system). Without the inclusion of proliferative markers, there was a 73% agreement between cytological and histopathological grading. The prediction of histopathological grade was slightly more accurate when assessing Ki-67 and Ki-67 × AgNOR signaling in cytological specimens (75% and 80%, respectively) compared to the initial cytological grading. The cytological assessment of canine MCTs proves beneficial for the initial evaluation, and the incorporation of the evaluation of Ki-67 and AgNOR markers may assist in identifying diagnostically highly malignant MCTs.

Argyrophilic nucleolar organizer regions staining for cytology smears in dogs and cats

The argyrophilic nucleolar organizer regions (AgNORs) are cellular proliferation markers, crucial for predicting the clinical course and aggressiveness of tumors. The purpose of this study was to establish an easy and practical AgNOR staining method in the cytology of dogs and cats. Air-dried cytological slides were prepared from dogs (n=14) and cats (n=12). Acetone, formalin, ethanol and methanol were tested as fixatives for AgNOR staining. Subsequently, various methods of Romanowsky-based counterstains were tested before and after AgNOR staining. Clear and strong AgNOR spots were observed with all fixatives, and post-May-Grünwald staining was the best counterstaining method. The established method showed clear AgNOR spots even in the long-term storage samples and Romanowsky-stained ones.

Relationship between Canine Lymphocyte AgNOR Counts and Haematological Indices of Health

A modified agyrophil technique was applied to peripheral blood smears to determine the mean AgNOR counts (MAC) of lymphocytes and ultimately assess the state of the lymphoid system in various clinical conditions of dogs. Fifty dogs, from clinically normal to pets with leukaemia, presented to the Veterinary Teaching Hospital, were recruited. Blood smears from each dog were stained with routine Romanowsky and modified agyrophil stains. Signalment, clinical diagnoses and hematologic parameters of the dogs were related to the MAC. An AgNOR proliferative index (AgPI) — percentage of lymphocytes with 3 or more AgNORs, was determined, and correlated with MAC. The statistical significance was determined at P < 0.05. MAC ranged from 1.17 in clinically healthy patients to 6.00 in leukaemic patients. The MAC was 2.00 in patients (n = 26) with lymphocyte counts within reference intervals (900—2400 per microliter); 2.23 in patients (n = 4) with lymphopenia; 2.18 in patients with lymphocytosis (n = 18) and 4.73 in patients (n = 4) with lymphocytic leukemia. Also, the MAC was 2.00 in non-anemic dogs while it was 2.47, 2.49 and 3.06 in patients with mild, moderate and severe anaemia, respectively. The MAC correlated strongly with AgPI (r = 0.91). The ancillary AgNOR technique provides a cheaper, more rapid and sensitive tool than routine lymphocyte counts in assessing the state of lymphoid proliferation in a variety of conditions in the dog.

Adaptation of the agyrophil technique for nucleolar organizer regions to canine peripheral blood smears

Nucleolar organizer regions (NORs) are chromosomal segments which are selectively stained by silver methods and evaluated as agyrophilic nucleolar organizer regions (AgNORs). The evaluation of AgNORs provides an insight into the level of cellular proliferation. This technique has extensively and sparsely been used in human and veterinary histopathology respectively. However, two major drawbacks have been irreproducible results and excessive staining precipitates. This study seeks to adapt the technique to canine peripheral blood smears in order to establish a routine staining protocol. Standardized volumes and concentrations of silver nitrate, gelatin, and formic acid were applied to smears at different temperatures for varying lengths of time. The technique was applied to unfixed and fixed smears. In some cases, a reducing agent (1% potassium iodide) was applied. It was shown that the optimum staining protocol was achieved by applying standardized solutions to a fixed smear at 46°C for 50 minutes. It is concluded that the staining protocol outlined in this study is practicable, and produces excellent and reproducible results that would enhance evaluation of AgNORs in canine peripheral blood cells.

A Case-Control Study of Oral Epithelial Proliferative Markers among Sudanese Toombak Dippers Using Micronuclei Assay, Argyrophilic Nucleolar Organizer Region, Papanicolaou and Crystal Violet Methods

The use of Toombak has been reported to play a major role in the etiology of oral cancer in Sudan. The cellular proliferative activity on the oral epithelium of 210 Toombak dippers was assessed by applying the micronuclei frequency, mean argyrophilic nucleolar organizer region (AgNOR) counts, Papanicolaou method, and 1% crystal violet stain. Participants were divided into 3 groups: 200 were apparently healthy individuals, 100 were Toombak users (cases), 100 were non-tobacco users (control) and 10 were patients with oral squamous cell carcinomas. Cytological atypia was identified among 4 (4%). Toombak users and was not found among the control group (P<0.04). The micronuclei frequencies were higher in Toombak users (1.026) than in the control group (0.356) (P<0.0001). The mean AgNOR counts in Toombak users (2.423) were higher than control group (1.303) (P<0.0001). Neither Toombak users nor control group showed mitotic figures in 1% crystal violet method. The results of this research showed that Toombak dipping is a high risk factor for increase in the cellular proliferation in the oral mucosa. The cytological proliferative marker methods used are useful for screening Toombak users.