In sebaceous cysts, echoes may be clumped within or dispersed throughout the hypoechoic mass. The contiguity with the skin and dramatic posterior acoustic enhancement are characteristic features. Patients and referring physicians are frequently aware of sebaceous cysts. Often, they are noted as incidental findings, but growth or inflammation may require their excision.

Sebaceous cysts are frequently located in the inframammary fold, axillary, and medial areas of the breast. When complicated by infection, the margins of these masses may become irregular and shaggy with thickening of the overlying skin. Neoplasm may be difficult to differentiate.