Cystic lesions of the breast: sonographic-pathologic correlation.

PURPOSE: To understand the pathologic basis for sonographic features of cystic lesions of the breast and determine appropriate assessment and management recommendations for these lesions based on sonographic appearance.

MATERIALS AND METHODS: From a database of 2,072 image-guided procedures performed from July 1995 through September 2001, 150 cystic lesions were identified. Diagnosis was established with fine-needle aspiration (n = 55), 14-gauge core-needle biopsy (n = 81), or both (n = 14). Excision was performed for all malignant (n = 18) and atypical (n = 2) lesions and for 11 benign lesions, which recurred or enlarged at follow-up. Imaging follow-up was available for 92 of 119 benign lesions. Targeted sonography was performed with high-frequency (10-MHz center frequency) transducers. Imaging and histopathologic, cytologic, and/or microbiologic findings were reviewed. Lesions were categorized as simple cysts, complicated cysts (imperceptible wall, acoustic enhancement, low-level echoes), clustered microcysts, cystic masses with a thick (perceptible) wall and/or thick (> or =0.5 mm) septations, intracystic or mixed cystic and solid masses (at least 50% cystic), or predominantly solid masses with eccentric cystic foci.

RESULTS: Of 150 lesions, 16 were simple cysts aspirated for symptomatic relief. Of 38 lesions characterized as complicated cysts and one cyst with thin septations, none proved malignant, nor did any of 16 lesions characterized as clustered microcysts. Of 23 masses with thick indistinct walls or thick septations, seven proved malignant. Of 18 intracystic or mixed cystic and solid masses, four proved malignant. Of 38 predominantly solid masses with eccentric cystic foci, seven proved malignant.

CONCLUSION: Symptomatic complicated cysts generally warrant aspiration. All clustered microcysts were benign, but further study is required. Cystic lesions with thick indistinct walls and/or thick septations (> or =0.5 mm), intracystic masses, and predominantly solid masses with eccentric cystic foci should be examined at biopsy; 18 of 79 of such complex cystic lesions proved malignant in this series.