Fig. 1.24
Fig. 1.25
Fig. 1.26
Fig. 1.27
Fig. 1.28
Fig. 1.29
Fig. 1.30
Fig. 1.31
Fig. 1.32
Some ANDIs represent changes predominantly of the phenotype of the epithelial cells and may lead to accumulation of secretion in the lobule, which in turn may calcify. Other forms of ANDIs represent architectural changes within the lobules, leading to marked enlargement of the TDLUs. The calcifications or the enlarged TDLUs may be mammographically or clinically detected, causing anxiety for the patient and differential diagnostic problems for the radiologist.
Fig. 1.33
Fig. 1.34
The histologically “normal” breast tissue may show numerous aberrations, many of which cannot be detected by clinical or radiologic examination. If these lesions are sufficiently large to be radiologically or clinically detected and, especially when symptomatic, they are more appropriately called “fibrocystic change,” which is still a variation of normal breast morphology.
The difference between ANDIs and fibrocystic change is more quantitative than qualitative. It is impossible to draw a sharp line between microcystic involution and cysts (Figs. 1.33 and 1.34) or between fibroadenomatoid change and fibroadenoma (Figs. 1.35 and 1.36).
Fig. 1.35
Fig. 1.36
The distinction between “normal” or “pathologic” depends on the method of examination. Histology is an extremely sensitive method and may detect many clinically and prognostically unimportant details, which are best characterized as variations and aberrations of the normal breast morphology.
The normal breast tissue contains lobules typical of both the proliferative and secretory and menstrual phases of the menstrual cycle, different combinations of involutional changes, and different ANDIs all at the same time. Consequently, normal breast tissue offers the interested examiner a variable and fascinating picture under the microscope (Figs. 1.37-1.41; Fig. 1.40, thick-section image).
Fig. 1.37
Fig. 1.38
Fig. 1.39
Fig. 1.40
Fig. 1.41
Fig. 1.42
Fig. 1.43
The mammogram represents a black-and-white summation of the morphologic details of the breast. The lobules are visible on a high-quality mammogram as l-to-2-mm nodular densities. Only the silhouettes of the lobules are seen, not the histologic details. A radiologic nodular density may represent a spectrum of histologic changes within the TDLU (Figs. 1.42-1.44). The radiologic linear densities correspond to ducts, fibrous strands, and vessels (Fig. 1.45).
Fig. 1.44
Fig. 1.45
Despite the variability of the histologic picture, the mammographic patterns of the normal breast can be properly classified in only five categories as described by Tabár, Gram and Tot. The basic factor determining the mammographic pattern of the normal breast is the interrelation between the radiopaque fibrous tissue and the radiolucent fatty tissue in the interlobular stroma.
Mammographic pattern I is characterized by Cooper ligaments as well as a harmonic distribution of fatty and fibrous tissue (Figs. 1.46-1.48).
Fig. 1.46
Fig. 1.47
Fig. 1.48
Fig. 1.49
Mammographic pattern II represents breast tissue replaced by fatty tissue with only a few remaining TDLUs (Figs. 1.49 and 1.50).
Fig. 1.50
Pattern I develops over time into pattern II through fatty involution. Hormone replacement therapy may convert pattern II back to pattern I. The mammographic pattern of the normal breast is often characterized as intermediate between patterns I and II or as