Pathologists and clinicians have been taught for decades that atypical lobular hyperplasia (ALH) and atypical ductal hyperplasia (ADH) of the breast are fundamentally different lesions. ALH has been viewed as a marker for subsequent carcinoma of lesser predictive power than lobular carcinoma in situ (LCIS), and associated with increased risk of carcinoma in either breast (although Page and colleagues did show that 2/3rds of subsequent carcinomas occur in the ipsilateral breast).
ADH has been viewed traditionally as a precursor lesion with more power than ALH to predict subsequent carcinoma, predominantly in the same breast. Surgeons will often do reexcisions when ADH is present at the margin but almost all will ignore margins positive for ALH (or even LCIS).
A recent article published in Cancer Prevention Research
based on a large study from the Mayo Clinic calls these assumptions into question. I recommend reading it and passing it on to your colleagues, both in pathology and the clinical specialties involved in breast disease management. There are a LOT more data in the text than are briefly discussed here.
The study involved almost 700 women with atypical hyperplasias, 330 with ADH, 327 with ALH, and 32 with both. This is by far the largest follow-up study in the literature on atypical hyperplasias of both types. To cut to the chase, the conclusion can be summarized in the following quote from the manuscript, "Our observations do not support present assumptions that ADH and ALH have substantively different behaviors. More DCIS may occur in women with ADH than ALH (25% vs. 13%, p=0.07), but numbers are small and this was not statistically significant."
Both ALH and ADH have features suggestive of precursor lesions and risk indicators. When carcinoma arises (either in-situ or invasive) both are predominantly associated with ductal as opposed to lobular carcinomas (ALH -> 77% ductal, 17% lobular; ADH -> 78% ductal, 8% lobular). Two-thirds of subsequent carcinomas arose in the ipsilateral breast in both ALH and ADH patients. Both ALH and ADH showed a tendency for contralateral carcinomas to develop later in life.
This is an valuable study that is packed with information, presented in a well-written format. Table 2 is especially data dense.
The authors conclude with the following:
"In summary, these findings underscore the importance of both ADH and ALH as premalignant lesions arising in an
altered tissue bed. The affected breast is at especially high risk for breast cancer in the first 5 years after diagnosis of breast cancer, with risk remaining elevated in both breasts long term. Both ADH and ALH portend risk for DCIS and invasive breast cancers, predominantly ductal, with two thirds moderate or high grade. These longitudinal data can help to inform clinical management strategies."
Although I think this is a very good study, I do have concerns that clinicians will interpret it to mean that ALH should treated more aggressively. I would argue that it rather suggests that ADH be treated more like ALH. The other problem(s), of course, are the distinctions between ALH & LCIS, and ADH & DCIS. A topic we've dealt with before.