Pregnancy-like (Pseudolactational) hyperplasia: A primary diagnosis in mammographically detected lesions of the breast and its relationship to cystichypersecretory hyperplasia

Pregnancy-like (pseudolactational) hyperplasia (PLH) has long been recogniz ed as an incidental finding in breast biopsies per formed for various clini cally detected benign and malignant conditions. The histologic features of PLH have been well described, including some instances exhibiting cytologic and structural atypia. The presence of calcifications in these lesions was rarely mentioned and was considered to be of little consequence. More rece ntly, however, calcifications in PLH have become the target of needle local ization and needle core biopsies. The authors report 12 instances in which PLH was the primary diagnosis in biopsy specimens obtained for radiographic abnormalities, usually calcifications. Six of 12 procedures (50.0%) were p erformed for mammographically detected calcifications, four cases for a mas s, one for an "abnormal mammogram," and one for galactorrhea. Calcification s were present in PLH in 10 biopsies, in benign terminal ducts in one speci men, and were not identified histologically in the remaining Specimen. In m ost instances, calcifications associated with PLH had smooth round or lobul ated contours and distinctive, internal, unevenly spaced laminations. Cysti c hypersecretory hyperplasia (CHH) was present in five specimens. In four o f the five specimens, CHH merged with PLH (PLH/CHH). Four of 12 specimens ( 33.3%) showed atypia within foci of PLH/CHH. PLH should be recognized as a primary diagnosis in breast biopsies for mammographically detected abnormal ities such as calcifications. Some calcifications associated with PLH have a distinctive histologic appearance, and their recognition can aid in the d iagnosis of PLH. Additional cases of PLH/CHH must be studied to ascertain t he clinical significance, if any, of this previously undescribed entity. Th e precancerous significance of PLH/CHH and of PLH with atypia has not been determined. In most instances, surgical excision would be prudent if PLH/CH H or PLH with atypia is present in a needle core biopsy specimen.