Manual of Diagnostic Cytology of the Dog and Cat

John Dunn

• Publisher: Wiley-Blackwell
• Year: 2014
• Print ISBN:
  9780470658703
• eBook ISBN:
  9781118783108
• Edition: 1
• Topic: Medicine
• Subtopic: Veterinary Medicine

Wish you could interpret cytological specimens in practice rather than paying a lab to do it for you?  Want to provide your clients with a faster service?

Manual of Diagnostic Cytology of the Dog and Cat is the ideal quick reference for the busy veterinarian in first opinion practice. It describes techniques for obtaining good quality cytological diagnostic specimens, and guides you through the interpretation of cytological findings.

Created to be used alongside the microscope, hundreds of high quality colour photos will help you to identify normal cell types and abnormal cytology, including both non-neoplastic and neoplastic lesions. It describes in a clear and concise manner the most common lesions and related disorders encountered in a practice setting. The concise format means that you can quickly find exactly what you're looking for.

Covering indications for cytological investigation, collection techniques and the evaluation and interpretation of findings, this concise manual will be your go-to resource.

1

Cytological Collection Techniques and Sample Preparation

Natali Bauer

Department of Clinical Sciences, Faculty of Veterinary Medicine, Clinical Pathophysiology and Clinical Pathology, Justus-Liebig University Giessen, Giessen, Germany

Acquisition of a fine-needle aspirate for cytological examination is a fast and easy, minimally invasive technique which can be performed in every practice or clinic. The advantages are that generally no anaesthesia or sedation is required and the risk of haemorrhage is minimal while the technique provides an excellent evaluation of single cell morphology. In contrast to histology, however, it has to be kept in mind that the tissue architecture is not preserved and cannot be evaluated. Histopathological examination of biopsy specimens allows the assessment of growth patterns and the margins of the lesion can be visualised if necessary, but surgical biopsy is associated with a higher risk of haemorrhage and anaesthesia (local or general) is necessary.

Adequate techniques of sample preparation and staining are mandatory for the optimal interpretation of cytological specimens. Moreover, correct interpretation of any cytological specimen requires correct microscopic examination and recognition of common artefacts. This chapter describes the practical approach to optimal sampling, routine staining techniques and the systematic microscopic evaluation and detection of common artefacts.

Sampling techniques

Fine-needle aspiration

Fine-needle aspiration cytology is a useful technique for the investigation of soft tissue masses (cutaneous lesions, lymph nodes, intra-thoracic or intra-abdominal masses) and effusions from body cavities. The technique can be easily performed in a practice setting. The following basic equipment is required:

• Glass slides with a frosted end which can be easily labelled.
• 5 ml syringe (if required also a 2 ml or 10 ml syringe; a 10 ml syringe might be advantageous for aspirating very firm masses),
• 20–22 G needles.
• A pencil for labelling the slides with the date and localisation of the lesion as well as the patient´s name. Note: Labels written with a ballpoint pen or marker may be washed away with alcohol-based stains (e.g. Diff-Quik, Wright’s, May–Grünwald–Giemsa).

Figure 1.1 Fine-needle aspiration using a needle and syringe.

For organs such as the liver or spleen, longer needles are usually required especially in large dogs. Here, a spinal needle with a stylet is recommended to avoid contamination by tissues adjacent to the mass or organ (with softer tissues smaller needles and syringes can be used).

Fine-needle aspirates can be taken with an ‘aspiration technique’ or a ‘non-aspiration technique’. The non-aspiration technique is preferred for sampling of all masses or organs which are highly vascular (e.g. spleen, liver) in order to minimise blood contamination. Overall, the sampling procedure should take no longer than 5–10 s, and several smears should be prepared.

• Aspiration technique:
  • The mass or organ (e.g. a peripheral lymph node) is immobilised with one hand and the needle is inserted with the other (Figure 1.1). Wherever possible, fine-needle aspiration of abdominal organs or masses is best performed under ultrasound guidance.
  • The skin is disinfected as for venipuncture.
  • The needle with attached syringe is inserted into the lesion.
  • The plunger is withdrawn, and while maintaining negative pressure, the needle can be redirected to aspirate different regions of the mass or organ.
  • The needle with attached syringe is removed after releasing the plunger.
  • The syringe is filled with approximately 3–5 ml air and reattached to the needle to expel the aspirate gently on the glass slide.
  • Note: To facilitate pulling the plunger, commercial aspiration guns may be useful when aspirating masses or organs which are difficult to immobilise since the vacuum can be easily maintained with one hand (Figure 1.2).
• Non-aspiration technique: Two methods of this technique can be used for sampling.
  • ‘Needle-alone technique’: The needle without the syringe attached is inserted into the lesion after disinfection of the skin (Figure 1.3). The needle is then rapidly moved back and forth in the tissue approximately ten times before it is withdrawn. A syringe already filled with 3–5 ml air ensures a rapid expulsion of the aspirated material onto the slide.
  • Alternatively, the needle is inserted with a syringe already filled with 2–3 ml of air attached (Figure 1.4). The needle and syringe are then rapidly moved back and forth in the tissue before the needle with syringe attached is removed. The aspirated material is then ejected onto the slide, and smears are prepared immediately.

Figure 1.2 Fine-needle aspiration using an aspiration gun, e.g. ‘Zyto-Gun^®’ (Scil animal care company GmbH, Viernheim, Germany).

Figure 1.3 The non-aspiration technique using a ‘needle-alone technique’ is useful for obtaining samples from small lesions such as pustules or bullae.

Figure 1.4 The non-aspiration technique with the syringe attached to the needle is used here to sample the spleen of a dog with ascites and icterus under ultrasonographic control. Note the syringe is prefilled with air and is held between the thumb and forefinger.

Cytological smears can be prepared using the blood sm...

Table of contents

• Cover
• Title page
• Copyright page
• Contributors
• Preface
• Editor’s Note
• 1 Cytological Collection Techniques and Sample Preparation
• 2 General Principles of Cytological Interpretation
• 3 Cytology of the Lymphoid Tissues
• 4 Cytology of Cutaneous and Subcutaneous Lesions
• 5 Cytology of the Respiratory Tract
• 6 Biochemical and Cytological Evaluation of Body Cavity Effusions
• 7 Cytology of Synovial Fluid
• 8 Biochemical and Cytological Examination of Cerebrospinal Fluid
• 9 Cytology of the Eye and Adnexal Structures
• 10 Cytology of the Urinary Tract
• 11 Cytology of the Liver, Exocrine Pancreas and Gastrointestinal Tract
• 12 Cytological Examination of the Endocrine Glands
• 13 Cytology of the Male and Female Genital Tracts
• 14 Cytology of Mammary Gland Lesions
• 15 Cytology of Selected Infectious Organisms
• Further Reading
• Index