Alternatively, ultrasound may be used to identify a subareolar mass (Fig. 7.4); however, one must be cautious in attributing the discharge to it if palpation of the mass does not reproduce the discharge (a “trigger point” as described by Haagensen) [5]. The elegance of the ductogram is that it has the potential to isolate the culprit duct and specifically localize the lesion for a more conservative surgical excision, particularly in the setting of multiple dilated ducts or duct ectasia [1, 4, 6, 7].

Sonographically, a papillary lesion commonly appears as a complex solid and cystic mass with circumscribed margins (Fig. 7.5); a solid mass in the subareolar region may also suggest this histology based on its location, particularly if it can be seen within a duct (intraductal). If seen radiographically without ductography, papillomas can be round to oval with circumscribed or spiculated margins and may have associated calcifications [1, 8, 9].

MRI is also being increasingly studied as a diagnostic tool in the evaluation of spontaneous discharge, with the advantage that it is noninvasive; cannulation and intraductal injection of contrast are avoided since MRI utilizes the intrinsic fluid signal of ducts on T2-weighted images. However, as with sonography, this may be less specific as it demonstrates all major subareolar ducts, not isolating the “culprit” duct contemporaneously with eliciting of discharge. Intravenous gadolinium contrast can increase sensitivity and specificity, since duct ectasia or intraductal debris may not enhance; however, it may not help in distinguishing between benign and malignant papillary lesions since both of these can enhance. Also, given the tiny size of most papillomas, and duct lumens, the use of specialized microscopic coils is advocated in improving image resolution over conventional MRI imaging [10–13]. At this time, all of this may be time- and cost-prohibitive given the more accessible and efficient methods of conventional ductography and sonography [5].

We refer patients for excisional biopsy of lesions found at ductography for alleviation of their symptoms (spontaneous discharge can become quite frustrating) and for confirmation of histology. A preoperative ductogram is done in the morning of surgery to guide the surgeon and the pathologist. After re-cannulating the duct, injecting a combination of radiopaque dye and methylene blue, radiographs are repeated and sent to the operating room with the patient for surgical planning.

Some papillomas are found incidentally at mammography or sonography in asymptomatic patients. We do not routinely recommend excision of core needle biopsy-proven solitary papillomas without atypia in these patients if there is radiologic-pathologic concordance, rather, we follow these patients. This has been controversial as previous data suggested a high rate of upstaging to malignancy on excision of papillomas. However, solitary papillomas without atypia are in fact not associated with an increased risk of malignancy; the upgrade rate has been documented as low as 2.3%—and as high as 36%; however some of the latter studies do not account for radiological-pathological congruence [14–19]. In our own patients, there was an 8.3% rate of malignancy in excised papillomas without associated atypia, compared to a 30–40% of those with atypia [15]. It is widely accepted that papillary lesions associated with atypia on core needle biopsy (termed as such, or as atypical papillomas) require excision, even if solitary. Papillomas that are associated with an increased risk of malignancy, even if atypia is not identified concurrently, are those classified as multiple peripheral papillomas, the appearance, diagnosis, and work-up of which are different than the solitary or central.

Multiple peripheral papillomas may be seen on imaging as similar appearing masses in a segmental or ductal distribution. Patients are typically asymptomatic. Biopsy for tissue diagnosis of representative lesions, if possible at two opposite extents, is sufficient. Excision is usually recommended due to the likelihood of malignancy.

Papillary carcinomas are further divided histologically as invasive or in situ. Typically larger and faster growing than benign papillomas, these may exhibit lager cystic spaces amidst solid components under ultrasound (Fig. 7.6) [1]. As with all papillary lesions, the presence of a fibrovascular core histologically makes these susceptible to bleeding following a needle biopsy.

Chapter 2 of this text contains some discussion on the pathology approach to diagnosis of papillary lesions. Selected radiologic-pathologic correlation of papillary lesions is highlighted below.