Hamartomas are encapsulated tumors that con­tain an abnormal mix of normal mammary tissues. They can grow quite large, often pre­senting as a discrete, mobile mass. On mammo­grams, hamartomas often have a distinctive appearance; they are smoothly marginated and separated from the surrounding breast by alucenthalo(Fig. 3–15). This has been described as a “breast within a breast.” If they are asymptomatic and not bothering the patient, and if a definitive diagnosis can be made based on mammography and biopsy, then observation is an option because these are invariably benign. If the diagnosis is uncer­tain or if the patient is bothered, excision is recommended.

Many women will sustain a trauma to the breast that will leave a mass in the breast, either a hematoma or fat necrosis. Hematomas typically present as the result of trauma or iat­rogenic injury. Spontaneous hematomas are extremely rare. The mass is typically painful and associated with ecchymosis. One of the biggest mistakes that can be made is to assume that a mass present in the breast after a trauma is a hematoma and to ignore it. Often a minor trauma will simply alert a patient to the pres­ence of a mass that was there before the event. This is especially true if there is ecchymosis associated with the mass.

If a hematoma is obvious, such as that caused by an iatrogenic injury, the hematoma will resolve with time. Treatment includes a good supportive bra and analgesics. Expanding hema­tomas require surgical evacuation and hemosta­sis. Likewise, conservative management of a hematoma after a reported trauma is reasonable if the storymatches the physicalfindings.Imme­diate imaging can be painful and it is reasonable to avoid it. However, careful follow-up is manda­tory to assure that the hematoma is resolving. If there is any question of a residual mass or a fail­ure to resolve, imaging and biopsy is recom­mended. Likewise, if the story and the findings raise any suspicion of malignancy, a thorough evaluation is warranted.

Papillary lesions of the breast are not well understood because they are relatively uncom­mon and incorporate a spectrum of lesions. These include single benign papillomas, papil­lomatosis, atypical papillomas, papillary DCIS, and invasive papillary carcinoma. Papillomas appear to be formed from hyperplasia of the duct epithelium supported by a fibrovascular core. This results in a pedunculated, friable tumor within the duct. They grow to about 1 cm in size, dilating the duct, and the friable epithelium often bleeds, causing a spontane­ous bloody nipple discharge. Sometimes a pal­pable mass can be felt near the nipple, and gentle pressure on it causes the discharge. They are primarily in one duct, usually in the major ducts beneath or within a few centi­meters of the nipple, but they can be more dis­tant, multiple, or in both breasts. When papillomas are located in the periphery of the breast and are associated with the terminal duct-lobular units, they are usually multiple and are often labeled as diffuse papillomatosis. Whereas papillomas can present clinically as a palpable mass or bloody nipple discharge, they may also be clinically occult, detected as an abnormal density on breast imaging.