Villonodular synovitis is a type of synovial swelling. Types include:

Pigmented villonodular synovitis
Giant cell tumor of the tendon sheathThough they have very different names, they have the same histology, and stain positive for CD68, HAM56, and vimentin. They are sometimes discussed together. == References ==
Chemistry
Crisaborole (chemical name: 4-[(1-hydroxy-1,3-dihydro-2,1-benzoxaborol-5-yl)oxy]benzonitrile) is a member of the class of benzoxaboroles characterized by the presence of a boronic acid hemiester with a phenolic ether and a nitrile. Crisaborole crystallizes into two polymorphs that differ in the conformation of the oxaborole ring. A cocrystal with 4,4-bipyridine has been prepared and studied by X-ray crystallography. History
Crisaborole was developed by Anacor Pharmaceuticals for the topical treatment of psoriasis. During preclinical and clinical development, crisaborole was called AN2728 and PF-06930164. The drug was assumed to be potential $2bn-a-year blockbuster, when Pfizer acquired Anacor Pharmaceuticals. However, the drug was commercially not successful, reaching only US$147 million in sales in 2018, and US$138 million in sales in 2019.Crisaborole was approved for use in the United States in December 2016 and for use in Canada in June 2018.The safety and efficacy of crisaborole were established in two placebo-controlled trials with a total of 1,522 participants ranging in age from two years of age to 79 years of age, with mild to moderate atopic dermatitis. In both trials participants received treatment with either crisaborole or placebo twice daily for 28 days. Neither the participants nor the health care providers knew which treatment was being given until after the trials were completed. Overall, participants receiving crisaborole achieved greater response with clear or almost clear skin after 28 days of treatment. The trials were conducted in the US.Crisaborole, approved for the treatment of mild to moderate atopic dermatitis in the European Union, has been rapidly withdrawn from the European market (March 2020 - February 2022).