Squamous metaplasia of lactiferous ducts
Squamous metaplasia of lactiferous ducts - abbreviated SMOLD is a change where the normal double layer cuboid epithelium of the lactiferous ducts is replaced by squamous keratinizing cell layers. The resulting epithelium is very similar to normal skin, hence some authors speak of epidermalization. SMOLD is rare in premenopausal women (possibly 0.1-3%) but more frequent (possibly up to 25%) in postmenopausal women where it does not cause any problems at all. SMOLD appears to be a completely benign lesion and may exist without causing any symptoms. In principle it ought to be completely reversible as the classification as metaplasia would suggest. Because of difficulties in observing the actual changes and rare incidence of the lesion this does not appear to be documented. The last section of the lactiferous ducts is always lined with squamous keratinizing epithelium which appears to have important physiological functions. For example, the keratin forms plugs sealing the duct entry and has bacteriostatic properties. In SMOLD the keratinizing lining which is supposed to form only the ends of the lactiferous ducts extends deep into the ducts. SMOLD is distinct from squamous metaplasia that may occur in papilomatous hyperplasia. It is believed to be unrelated to squamous cell carcinoma of the breast which probably arises from different cell types. The keratin plugs (debris) produced by SMOLD have been proposed as the cause for recurrent subareolar abscesses by causing secretory stasis. The epidermalized lining has also different permeability than the normal lining, hindering resorption of glandular secretions.
Also called Zuskas disease (only nonpuerperal case), subareolar abscess is a subcutaneous abscess of the breast tissue beneath the areola of the nipple. It is a frequently aseptic inflammation and has been associated with squamous metaplasia of lactiferous ducts. The term is usually understood to include breast abscesses located in the retroareolar region or the periareolar region but not those located in the periphery of the breast. Subareolar abscess can develop both during lactation or extrapuerperal, the abscess is often flaring up and down with repeated fistulation. Pathophysiology
90% of cases are smokers, however only a very small fraction of smokers appear to develop this lesion. It has been speculated that either the direct toxic effect or hormonal changes related to smoking could cause squamous metaplasia of lactiferous ducts. It is not well established whether the lesion regresses after smoking cessation. Extrapuerperal cases are often associated with hyperprolactinemia or with thyroid problems. Also diabetes mellitus may be a contributing factor in nonpuerperal breast abscess. Treatment
Treatment is problematic unless an underlying endocrine disorder can be successfully diagnosed and treated. A study by Goepel and Panhke provided indications that the inflammation should be controlled by bromocriptine even in absence of hyperprolactinemia.Antibiotic treatment is given in case of acute inflammation. However, this alone is rarely effective, and the treatment of a subareaolar abscess is primarily surgical. In case of an acute abscess, incision and drainage are performed, followed by antibiotics treatment.