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.
Tiopronin, sold under the brand name Thiola, is a medication used to control the rate of cystine precipitation and excretion in the disease cystinuria. Due to the rarity of the disorder, tiopronin falls under the classification of an orphan drug. It is somewhat similar to penicillamine in both chemistry and pharmacology.A generic version of tiopronin is available in the United States as of April 2021. Uses
Tiopronin is used primarily for cystinuria and is well known in the cystinuric community. Depending on the severity of a persons cystinuria, tiopronin may be taken for life, possibly starting in early childhood. The drug works by reacting with urinary cysteine to form a more soluble, disulfide linked, tiopronin-cysteine complex. Side effects
Tiopronin may present a variety of side effects, which are broadly similar to those of D-penicillamine and other compounds containing active sulfhydryl groups. Its pharmacokinetics have been studied. Society and culture
In the U.S., the drug was marketed by Mission Pharmacal at $1.50 per pill, but in 2014 the rights were bought by Retrophin, owned by Martin Shkreli, and the price increased to $30 per pill for a 100 mg capsule.In 2016 Imprimis Pharmaceuticals introduced a lower cost version marketed as a compounded drug. Research
It may also be used for Wilsons disease (an overload of copper in the body), and has also been investigated for the treatment of arthritis, though tiopronin is not an anti-inflammatory.Tiopronin is also sometimes used as a stabilizing agent for metal nanoparticles. The thiol group binds to the nanoparticles, preventing coagulation. References
External links
"Tiopronin". Drug Information Portal.