Pattern IN is characterized by a relatively fibrotic area behind the nipple when the remainder of the breast has been replaced by adipose tissue (Fig. 1.51). The same pattern can be produced by advanced ductectasia.
Fig. 1.51
Fig. 1.52
Fig. 1.53
Fig. 1.54
Fig. 1.55
Pattern IV is dominated by somewhat enlarged nodular densities, approximately 3 to 5 mm in size (Figs. 1.52 and 1.53). These densities usually represent different ANDIs, but focal involution of the interlobular stroma with small islands of remaining fibrous tissue may present the same picture (see Fig. 1.43).
Pattern V shows a radiopaque density over the entire gland corresponding to a more collagenous interlobular stroma (Figs. 1.54 and 1.55). Radiologic details (nodular or linear densities) are poorly seen; active and/or atrophic parenchyma may be hidden within this density. Patterns IV and V are stable and do not change during the woman's lifetime.
Conclusions
Comprehensive knowledge of the variations of normal breast morphology enables the pathologist to avoid over-diagnosing normal variations as pathologic processes.
Clinical and radiologic diagnoses assist the pathologist in the delineation of normal tissue from fibrocystic change.
The particular mammographic pattern of breast tissue is an important aid for the pathologist. Detection of pathologic changes in breasts with patterns I, II, and III is relatively easy, but a more detailed histologic analysis of macroscopically and radiologically normal breast tissue is necessary in patients with patterns IV and V.
References
1 Vogel PM, et al. The correlation of histological changes in the human breast with the menstrual cycle. Am J Pathol. 1981;104:23–34.
2 Longacre TA, Bartow SA. A correlative morphologic study of human breast and endometrium in menstrual cycle. Am J Surg Pathol. 1986;10(6):382–393.
3 Hughes LE, et al. Aberrations of normal development and involution (ANDI): a new perspective on pathogenesis and nomenclature of benign breast disorders. Lancet. 1987;2(8571):1316–1319.
4 Gram IT, Funkhouser E, Tabár L. The Tabár classification of mammographic parenchymal patterns. Eur J Radiol. 1997;24:131–136.
5 Tot T, Tabár L, Dean PB. The pressing need for better histologic-mammographic correlation of the many variations in human breast anatomy. Virchows Arch. 2000;437:338–344.
6 Tabár L, Dean PB, Tot T. Teaching atlas of mammography. 3rd ed. Stuttgart, New York: Georg Thieme Verlag; 2001.
Chapter 2
General Morphology of Breast Lesions
Most pathologic processes in the breast originate in the terminal ductal-lobular units (TDLUs). The affected TDLUs are distended, distorted, or destroyed by the accumulation of fluid, mucin, cancer cells, necrotic debris, or calcium in the lumina of the acini and of the terminal duct or by the accumulation of collagen, glycoproteins, or stromal cells in the intralobular stroma (Fig. 2.1, thick-section image).
Fig. 2.1
If the pathologic process primarily distends and distorts the TDLU, spherical or oval lesions develop (Fig. 2.2, thick-section image).
Fig. 2.2
If the pathologic process destroys and replaces the pre-existent TDLU, a stellate lesion may develop (Fig. 2.3, thick-section image).
Fig. 2.3
All pathologic processes lead to a considerable enlargement of the TDLU. In neoplasia, the largest diameter of the largest invasive lesion is considered to be the tumor size.
As a result of distension or destruction, or both, most breast tumors are round/oval (Fig. 2.4) or stellate (Fig. 2.5).
Fig. 2.4
Fig. 2.5
By coalescence of the distended, distorted, and destroyed structures and invasion of the tumor into the interlobular stroma, the shape of the lesion may become increasingly complex (Fig. 2.6).
Fig. 2.6
Fig. 2.7
Fig. 2.8
Fig. 2.9
Fig. 2.10
Fig. 2.11
Fig. 2.12
The spherical/oval shape is not tumor-specific and can be seen in different pathologic processes, such as: cysts (Figs. 2.7 and 2.8) and fibroadenomas; medullary (Fig. 2.7), mucinous (Fig. 2.4), and ductal carcinomas (Fig. 2.9); metastases in the breast (Fig. 2.10); and malignant mesenchymal tumors (Figs. 2.11 and 2.12).
On the other hand, stellate lesions are usually carcinomatous, but may seldom be radial scars or fibrous scars (Fig. 2.13, thick-section image).
Fig. 2.13
Fig.