Background: Simple and complicated cysts in the breast are most common in women between the ages of 30-50 and can be distinguished from solid masses on ultrasound. However, in real life practice, the differentiation between benign simple and complicated cysts from malignant cystic lesions is not always so straight forward.
The following sonographic criteria must be met in order to characterize a mass as a simple cyst: oval or round shape, anechoic, circumscribed margins, and posterior acoustic enhancement. If one of these characteristics is absent or if there is a co-existing suspicious trait, such as angulated margins, then aspiration with possible conversion to biopsy should be recommended. A complicated cyst has the same features as a simple cyst except that it contains low-level internal echoes due to debris, protein, cholesterol, blood, white blood cells and/or epithelial cells.
The distinction between a simple/complicated cyst and a malignancy, however, can be difficult. In addition, simple cysts are extremely common in the general population and are seen more frequently with screening breast ultrasounds. At our institution, we have encountered 10 cases of cystic lesions that, on preliminary review, were labelled as simple/complicated cysts. Due to the presence of at least one suspicious characteristic, however, these have all underwent aspiration/biopsy and returned as malignancy.
Learning Objectives: 1. Describe the established sonographic criteria for a simple cyst. 2. Recognize subtle findings on ultrasound that are suspicious. 3. Know when to recommend an aspiration/biopsy. 4. Understand the types of malignancies that can mimic a seemingly simple cyst.
Abstract Content/Results: We will present a pictorial review comprising of 10 multi-modality cases showing malignancies that resemble simple cysts on ultrasound. All cases will include ultrasound, but the majority will also include mammography, MRI, and PET-CT. In our cohort, we have 5 cases of IDC, 2 DCIS, 1 ILC, 1 metaplastic, and 1 metastatic melanoma.
Conclusion: Our exhibit shows several cases of seemingly simple or complicated cysts that have either failed to meet all benign criteria or demonstrate a co-existing suspicious feature. These masses have undergone biopsy and returned as malignancy. Additionally, we have learned that although sonography is the modality relied upon to label a lesion as a cyst, it is equally as important to scrutinize the mammographic margins of these lesions, which is feasible with the advent of 3D digital tomosynthesis. It is our hope that others may benefit from our experience, thereby reducing the incidence of missed cancers.
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