Cyst fluid cytology

Cyst fluid from various sites (eg, thyroid, ovary, breast) should be sent to the laboratory as soon as possible after aspiration.

Optional wet fixed (95% ethanol) and/or air dried direct smears may be made at the time of aspiration.

Refrigerate or add equal volume of 50% ethanol to the fluid if more than 24hr delay to laboratory.

Clinical information may be essential for interpretation of some conditions.

Macroscopic comment.

Microscopic examination of Papanicolaou and Romanowsky stained cellular component of smears and/or centrifuged fluid; measurement of oestrogen levels in ovarian cyst fluids.

Investigation of cystic lesions at various sites to determine the nature of the underlying process.

Identification of the nature of the cystic lesion, especially in the differentiation of benign and malignant processes. 

High levels of oestrogens in an ovarian cyst are indicative of a follicular origin.

Interpretation of borderline and low grade lesions may prove difficult due to minimal morphological changes.

Marked reactive and degenerate changes in benign fluids may show marked nuclear atypia resulting in equivocal diagnosis.