The traditional method of obtaining a tissue diagnosis of a palpable breast mass is the EBB. If the practitioner feels a suspicious mass, then the next appropriate step is to obtain diagnostic imaging in the form of a bilateral mammogram and a unilateral ultrasound directed at the suspicious lesion. The ultrasound will distinguish a simple cyst from a complex cyst or solid mass in addition to further characterization of any solid lesion. The bilateral mammogram will effectively screen the contralateral breast and provide comparison in the parenchymal tissue pattern between both breasts.
If the imaging is noncontributory but the practitioner is still concerned about the palpable mass, the option of fine-needle aspiration, percutaneous core biopsy (PCB), or an EBB should be considered. At any time, the patient may opt for EBB rather than observation or PCB.
If an indeterminate solid lesion or calcifications are identified by mammogram or ultrasound, an image-guided PCB is the preferred approach for tissue diagnosis. If the practitioner cannot perform an image-guided PCB personally or does not have a local radiologist who can perform a PCB, then image-guided localization and EBB are indicated.
A radial scar has a very distinct mammographic pattern, characterized by a spiculated density, often with a radiolucent center. An EBB is usually the most efficient means of making the diagnosis of radial scar because a benign result obtained by PCB would be considered discordant with the suspicious imaging characteristics, and an EBB would ultimately be recommended. In addition, occult malignancy has been reported in 4% of patients diagnosed with radial scar by PCB who subsequently underwent EBB.1 A patient who presents with pathologic nipple discharge and has a retroareolar lesion seen by mammogram, ultrasound, or ductogram should also undergo an EBB because the lesion often represents a papillary lesion. The diagnosis of a papillary lesion on PCB should prompt an EBB for definitive diagnosis to rule out a papillary carcinoma, and therefore PCB is often not helpful in establishing a benign diagnosis.
Once a PCB has been performed (either directed by palpation or image-guided), the tissue diagnosis may prompt an EBB. EBB is indicated if the PCB results reveal lobular carcinoma in situ (particularly if the lobular carcinoma in situ is associated with necrosis or calcifications), atypical ductal hyperplasia, atypical lobular hyperplasia, columnar cell lesion with atypia, radial scar, or a papillary lesion. The concern regarding these diagnoses obtained by PCB is that an error in sampling by the radiologist or an error in interpretation by the pathologist may have occurred, which can produce a false-negative diagnosis. The diagnosis of columnar cell lesion with atypia is concerning because of the high association of this lesion with tubular carcinoma. Approximately 80% of patients with tubular carcinoma have associated columnar cell lesions with atypia.2,3
Table 53-1 summarizes recent literature regarding the incidence of carcinoma diagnosed by EBB after atypical results at PCB. These studies are limited by small numbers, retrospective design, a variety of PCB indications, bias regarding which patients were chosen for EBB, and limited discussion regarding satisfaction by the radiologist that the lesion in question was accurately sampled at PCB. Nevertheless, the frequent finding of carcinoma at excision after a PCB diagnosis of atypia warrants consideration.
Any benign diagnosis that is obtained by PCB must be confirmed as a concordant result by the physician who performed the biopsy. Only the physician who performed the biopsy can determine that the lesion was sampled appropriately during the procedure and that a benign diagnosis is a reasonable result. Depending on the level of suspicion by the physician who performed the biopsy, a benign result may be considered discordant with the imaging characteristics, and an EBB is then indicated. For this reason, the clinician should confirm concordance with the radiologist before conveying PCB results to the patient.
There are many situations in which a PCB is not technically feasible, and therefore an EBB is the only means of obtaining a tissue diagnosis of an image-detected indeterminate lesion. Patients with lesions that are too superficial or immediately retroareolar cannot undergo a PCB due to the possibility that the core needle may inadvertently exit the skin after passing through the superficial lesion. The possibility of the core biopsy needle passing into and out of (“through and through”) the breast during the PCB procedure is also a concern in patients undergoing a biopsy that requires breast compression (mammogram or magnetic resonance imaging [MRI]–guided) when the breast itself compresses substantially. The compression of the breast is often noted on the diagnostic mammogram, and a breast that compresses to less than 30 mm can make a PCB very challenging, if not impossible.
Posterior lesions may not be accessible for stereotactic biopsy due to limitations in patient positioning on the stereotactic table. In addition, inadvertent injury to the pectoralis major, intercostal muscles, ribs, or pleura is possible during PCB of extreme posterior lesions in thin women and should be avoided. Care must be taken in performing a PCB in a woman with retroglandular breast augmentation as the core needle can easily damage an implant. The radiologist may decide that the lesion is too close to the implant to perform a PCB safely and request an EBB for tissue diagnosis. Occasionally, PCB will be attempted but deemed unsuccessful by the radiologist due to inadequate sampling. This situation can occur in patients with extremely dense breast tissue or in patients with very faint indeterminate calcifications that are not well visualized during the stereotactic procedure.
Finally, patient compliance and patient habitus may make a PCB unfeasible. An EBB is necessary for a patient who cannot cooperate during a PCB procedure for any number of reasons (ie, anxiety, pain, mental disability). Patients with severe kyphosis or pectus excavatum may find it difficult to be positioned appropriately in the prone position for a stereotactic or MRI-guided PCB. These patients may require an EBB in the supine position for diagnosis.
