Rosen's Breast Pathology, 4e

900

Chapter 33

breast tissue in about half of the cases. Nearly 20% had DCIS (Figs. 33.3 and 33.4). IDC accounted for 20% of the cases (Fig. 33.5), and about 10% had invasive lobular carcinoma (ILC) (Fig. 33.6). The IDCs have well-differentiated to mod­ erately differentiated lesions. It is exceedingly unusual for special types of duct carcinoma to arise in a FA or PT. Atypi­ cal epithelial lesions in fibroepithelial tumors are prone to having a conspicuous myoepithelial component, and are associated with a variety of findings, including sclerosing adenosis (SA), cysts, apocrine metaplasia, and calcifica­ tions, which constitute the so-called complex FA. Petersson et al. 111 described a complex FA that gave rise to a low-grade in situ and invasive ductal carcinoma (IDC) associated with columnar cell change. The probability of finding carcinoma in breast tissue out­ side a FA that is involved by carcinoma has been difficult to determine on the basis of published reports, because many patients were treated only by excisional biopsy. A literature review of 62 published cases found extra-fibroadenomatous carcinoma in 42% of patients. 104 Diaz et al. 99 reported that the type and amount of carcinoma in a FA and the age at diagnosis were not significant predictors of the likelihood of finding carcinoma in the surrounding breast tissue. Among

women treated by mastectomy, carcinoma was limited to the FA in one-third to one-half of cases that had LCIS, DCIS, or ILC. 101,104 IDC that arose in a FA involved the surrounding breast tissue in at least 50% of cases. With rare exceptions, the same type of carcinoma has been found in the FA and in the breast tissue. LCIS may be detected in multiple FA in one breast or in bilateral FA. 100 ALNmetastases have arisen from invasive carcinoma present exclusively within a FA in two cases. 97,112 Ten percent to 15% of patients with carcinoma in a FA have had contralateral carcinomas concurrently or pre­ viously treated. 96,100,101 The opposite breast contained IDC in the majority of these cases. Subsequent contralateral carci­ noma has been described in about 6% of cases. 99 Phyllodes Tumor Florid hyperplasia involving epithelial and myoepithelial cells is often encountered in PT. The degree of atypia in the epithelial hyperplasia parallels that of the stromal compo­ nent in some but not all cases. Mitoses may be seen in hyper­ plastic epithelial and myoepithelial cells. Carcinomas arising in PT are histologically similar to carcinomas developing in FA. LCIS (Fig. 33.7) is less

FIG. 33.3.  Fibroadenoma, intraductal carcinoma. A: Crib- riform growth pattern. B: Apocrine cytology. C: Cribriform and solid types of DCIS involving a FA and glands within its vicinity.

C