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Definition

Cysts within the breast are fluid-filled, epithelium-lined cavities that may vary in size from microscopic to large, palpable masses containing as much as 20 to 30 mL of fluid.

Clinical Manifestation

· A palpable cyst develops in at least 1 in every 14 women, and 50% of cysts are multiple or recurrent. The pathogenesis of cyst formation is not well understood. However, cysts appear to arise from destruction and dilation of lobules and terminal ductules.

· Cysts are influenced by ovarian hormones, a fact that explains their variation with the menstrual cycle. Most cysts occur in women older than 35. The incidence of cyst development steadily increases until menopause and sharply declines thereafter. New cyst formation in older women is generally associated with exogenous hormone replacement.

Laboratory Findings

· A palpable mass can be confirmed to be a cyst by aspiration or ultrasound. Cyst fluid can be straw colored, opaque, or dark green and may contain flecks of debris. Given the low risk for malignancy within a cyst, if the palpable mass disappears completely after aspiration and the cyst contents are not grossly bloody, the fluid need not be sent for cytologic analysis.

· If the cyst recurs multiple times (more than two times is a reasonable rule), cytology is justified.

· Microscopic studies have shown that fibrosis at or near the lobule, combined with continued secretion, results in unfolding of the lobule and expansion of an epithelium-lined cavity containing fluid.

Treatment

· Aspiration

· Surgery

Surgical removal of a cyst is usually indicated if the cytologic findings are suspicious or the cyst recurs multiple times.