Internal Medicine Specialist Evidensia Södra Djursjukhuset Kungens Kurva Södertälje , Stockholms Lan, Sweden
Disclosure(s):
Cameron Prior, BVSs MSc CertAVP ECVIM-CA MRCVS: No financial relationships to disclose
Fine-needle aspiration (FNA) cytology may be used to characterise adrenal masses. However, only a few studies have compared the sensitivity/specificity of adrenal cytology in cats and dogs with histopathological assessment. Cases were included if both adrenal cytology and histopathology reports were available. Data was collected using CastorEDC, and results from ancillary tests were recorded. Sensitivity and specificity were calculated using histopathology as the reference standard. Data from 70 cases (64 dogs, 6 cats) across 17 centres were included. Adrenal histopathology identified phaeochromocytomas in 37/70 (53%) and adrenocortical tumours in 31/70 cases (44%). The remaining diagnoses were neuroblastoma and mixed neuroendocrine carcinoma. Cytological assessment correctly identified adrenal cortical or medullary tumours in 61/70 cases (87%). Cytology was non-diagnostic in 7% of cases (n = 5). Sensitivity and specificity for phaeochromocytomas were 73% (95% CI: 56%–86%) and 91% (95% CI: 76%–98%), respectively. Sensitivity and specificity for adrenocortical tumours were 77% (95% CI: 59%–90%) and 87% (95% CI: 73%–96%), respectively. Multivariable binary logistic regression identified markedly vacuolated cytoplasm (OR 0.06, p = 0.001, 95% CI: 0.01–0.28) and uniform naked nuclei (OR 8.41, p = 0.001, 95% CI: 2.44–34.82) as significant cytological predictors of phaeochromocytoma. Among the 50 cases with documented complications, 4% (n = 2) involved cortical adenomas with post-FNA bleeding. One dog required surgical intervention, while the cat recovered without treatment. This study demonstrates that cytological findings may complement the diagnostic investigation of adrenal masses. Although the sensitivity of adrenal cytology was moderate, its specificity for phaeochromocytomas was high. While cytology cannot be relied upon as the main diagnostic modality for adrenal masses, the absence of markedly vacuolated cytoplasm and presence of uniform naked nuclei are independent predictors of phaeochromocytoma
Learning Objectives:
Describe the diagnostic performance (sensitivity and specificity) of fine-needle aspiration (FNA) cytology for adrenal masses in dogs and cats compared with histopathology.
Interpret cytological features that differentiate adrenocortical tumours from phaeochromocytomas, including the significance of markedly vacuolated cytoplasm and uniform naked nuclei.
Evaluate the clinical utility and limitations of adrenal FNA cytology in the diagnostic work-up of adrenal masses.
Recognise potential complications associated with adrenal FNA and incorporate risk assessment into clinical decision-making.
