🎓 Clinical Note: How not to confuse oncocytoma with carcinoma?
Diagnosing salivary gland tumors with a predominance of oncocytic cells is a challenging task even for experienced cytologists. The main difficulty when examining fine-needle aspiration (FNA) material lies in the morphological similarity between benign oncocytoma and acinic cell carcinoma. Errors in this matter are critical, as they determine the treatment strategy: from observation to radical surgery. 🏥
A group of researchers (Ahn et al., 2024) drew attention to an important detail that is often overlooked. This refers to the structure of connective tissue in the sample.
🔍 Key Diagnostic Feature
During a retrospective analysis of 11 cases, it was established that oncocytoma is characterized by the presence of large arborizing fragments of fibrovascular tissue, densely populated by monomorphic (“bland”) oncocytes.
How it looks: Tree-like structures of vessels and connective tissue are visible in the cytological preparation, serving as a kind of “framework” for the tumor cells. 🌳 Statistics: This feature was found in 5 out of 6 cases of confirmed oncocytoma. For comparison: among cases of acinic cell carcinoma, such a picture was encountered only once.
💡 Why is this important for the clinician?
- Differential Diagnosis: If you see arborizing vascular fragments in the smear in combination with cells without signs of atypia, oncocytoma should be your primary working diagnosis. 📋
- Prevention of Overdiagnosis: The presence of such structures helps to avoid a false-positive conclusion of malignancy (acinic cell carcinoma) in situations where other criteria are not pronounced.
- Limitations: Although this feature is not absolutely specific (100%), its manifestation is a strong argument in favor of a benign process.
Summary for practice: A thorough search for arborizing fibrovascular fragments when examining oncocytic neoplasms of the salivary glands increases the accuracy of the cytological diagnostic stage. This is a simple but effective marker that helps distinguish a “quiet” benign process from a hidden threat. ✨
Source for citation: Ahn J, Holmes MP, Zhao P. Fine Needle Aspiration of Oncocytic Neoplasm of the Salivary Gland: Prominent Arborizing Fibrovascular Tissue Fragment With Bland Oncocytes Is an Underrecognized Characteristic Feature of Oncocytoma. Journal of the American Society of Cytopathology. 2026.
