While there are several different methods that may be used to biopsy skin, punch biopsy has the ability to sample the subcutaneous fat. This is a simple office procedure that employs a punch instrument that may range in size from 2 to 8 mm. After adequate local anesthesia is infused, the physician simply holds the skin taught and twists the instrument perpendicular to the skin until it has penetrated the dermis to reach the subcutaneous tissue. The wound may be closed with either adhesive strips or a non-absorbable suture.

Surgical excision for the purposes of obtaining a tissue diagnosis should only be performed when there is no access via image guidance. The technique performed is the same as for an image localized lumpectomy. The goal should not only be to obtain a tissue diagnosis but to also completely excise the lesion with clear margins. For a complete description of the procedure, please see the chapter of this book on breast lumpectomy.

As compared to open biopsy, an image-guided minimally invasive approach offers similar accuracy with lower complication rates. While adverse outcomes such as a seroma or hematoma may occur, adequate compression is often all that is necessary following the procedure to ensure hemostasis. More serious complications, including pneumothorax and retained wire fragments, have been described but are quite rare [7].

After any biopsy of a breast lesion, the pathologic findings largely determine next steps in follow up. Patients with benign pathologic findings that are concordant with imaging should be followed with physical exam and regularly-scheduled imaging, if age-appropriate. For lesions that are found to be malignant, planning for surgical excision versus neoadjuvant therapy should be employed. For patients with indeterminate pathology, atypical ductal hyperplasia, lobular carcinoma in situ, flat epithelial atypia, benign pathology with discordant imaging, intraductal papillomas or otherwise pathologically concerning lesions, an open surgical excision for a representative sample of tissue may need to be performed.