Lymph node cytology: lymphoma or reactive hyperplasia
6-year-old Rottweiler with painless enlargement of all peripheral lymph nodes. Fine-needle aspiration of the popliteal node is performed.
| Parameter | Result | Reference |
|---|---|---|
| Large lymphocytes (> 2 RBC diameters) | 80 % | < 10% in normal node |
| Small mature lymphocytes | 15 % | > 75% in normal node |
| Plasma cells | Few | — |
| Mitoses | Frequent | — |
What is the most likely cytological interpretation?
chevron_right Show answer and explanation
A. Large cell (high-grade) lymphoma
Correct. A monomorphic population with more than 50% large lymphocytes, few plasma cells and frequent mitoses is diagnostic of high-grade lymphoma. Immunophenotyping (flow cytometry or PARR) adds prognostic information.
B. Reactive lymphoid hyperplasia
In a reactive node small lymphocytes predominate, with increased intermediate and large lymphocytes and plasma cells: a heterogeneous population. Here it is almost monomorphic.
C. Neutrophilic lymphadenitis
This would require a clear increase in neutrophils, often with bacteria or necrosis. No neutrophils are described, but a large lymphoid population is.
D. Metastatic carcinoma
Carcinoma metastases appear as cohesive clusters of epithelial cells foreign to the node, not as discrete large lymphocytes.
lightbulb Key takeaway
Avoid aspirating the mandibular nodes (often reactive from the oral cavity); the popliteal or prescapular nodes are more representative. If there are many small and intermediate lymphocytes and low-grade lymphoma is suspected, cytology is not enough: request histopathology, flow cytometry or PARR.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.