Fine Needle Aspirates & Cytology

When a mass, swelling, or fluid needs to be evaluated, examining the cells directly can provide valuable information. Cytology allows us to look at a small sample under a microscope to help understand what may be present and guide the next steps in your pet's care.

Some areas can be sampled based on their location and feel, while deeper structures may require ultrasound guidance to help position the needle safely and accurately.

Once collected, the cells are placed onto microscope slides and prepared for cytologic evaluation.

Cytology is the examination of individual cells under a microscope. It can help identify whether a sample appears benign, inflammatory, infectious, or cancerous or it may sometimes reveal the type of tumor present.

Certain cancers, including many mast cell tumors and other round-cell tumors, can often be identified effectively through the needle aspiration and cytology. Other growths may not release enough representative cells to establish a definitive diagnosis this way.

A fine-needle aspirate and cytology may be recommended to:

• Evaluate a new or changing lump
• Examine an enlarged lymph node
• Sample an internal organ or mass identified through imaging
• Investigate an area with fluid accumulation
• Help determine whether a finding may be cancerous
• Assess whether cancer may have spread to another location
• Inform treatment planning or lead to additional testing needs

The value of sampling depends on the location, type of tissue, and clinical question we are trying to answer. Our oncology team will explain what we hope to learn and how the findings may influence your pet’s care.

Many superficial samples can be collected quickly without sedation. Your pet will be positioned carefully, and a small needle will be used to collect cells from the area.

Sedation may be recommended when an area is difficult to reach, when a pet is anxious or uncomfortable, or when a sample needs to be obtained from an internal structure with ultrasound guidance. In these cases, we will explain the recommendation and what the procedure may involve before proceeding. We will also explain any recommendation before the procedure is performed.

Cytology can sometimes provide a diagnosis or strongly indicate the type of process present. In other cases, the results may not be conclusive without a biopsy and providing a complete answer.

A sample may not always release enough cells, or the cells collected may not represent the area completely. When more information is needed, we may recommend repeating the aspirate, submitting additional testing, or obtaining a tissue biopsy for histopathology.

We will explain what the findings tell us, what they do not yet establish, and how they may shape the recommendations that follow.