The clinical value of image cytometry DNA analysis in distinguishing branchial cleft cysts from cystic metastases of head and neck cancer

OBJECTIVES/HYPOTHESIS: A branchial cleft cyst presents as a lump in the neck that, generally, is easily cured by surgical excision. The preoperative diagnosis is based on clinical examination and, especially in the Scandinavian countries, fine-needle aspiration cytology. However, at times, the histopathological analysis of the excised cyst reveals a cystic metastasis of squamous cell carcinoma of the head and neck. If adequate diagnosis could be obtained preoperatively, patients would most likely fare better. The study was performed to investigate whether the diagnostic accuracy for these lesions could be improved preoperatively by image cytometry DNA analysis of the fine-needle aspiration cytology specimen. STUDY DESIGN: Image cytometry DNA analysis was performed on the preoperative fine-needle aspiration cytology specimen and the surgical specimens from 51 patients with solitary cysts in the lateral region of the neck. Thirty-six patients were selected because there was a discrepancy between findings on fine-needle aspiration cytology and the final histopathological diagnosis or an uncertain cytological diagnosis. There were 25 metastatic squamous cell carcinomas and 3 thyroid cancers, there was 1 lymphoma and 1 sialoadenitis, and there were 21 branchial cleft cysts. METHODS: The cytodiagnostic Giemsa-stained slides were destained in Methanol and then stained with Schiff's reagent. The paraffin-embedded material from excised cysts were cut and deparaffinized and then stained with Schiff's reagent. Ahrens image analysis was used for DNA analysis and lymphocytes were used as control cells. DNA valves exceeding 5c was regarded as aneuploid. RESULTS: Image cytometry DNA analysis of the preoperative cytological specimen was possible in 41 of 51 patients. We found that in 53% of the cases with cystic metastasis, image cytometry DNA analysis, when possible, revealed aneuploidy, thus indicating malignancy. DNA analysis showed diploidy in all benign cases. CONCLUSIONS: Aneuploidy is highly specific for malignancy. Image cytometry DNA analysis increases the diagnostic sensitivity for malignant cystic metastasis and therefore is a valuable supplement to conventional cytological study for these lesions.