Also known as: digital myxoid pseudocyst, digital synovial cyst.
- Dome-shaped papule or nodule on the dorsal proximal nail fold or over an interphalangeal joint
- Contains viscous mucoid material
- Cystic mucin-containing spaces devoid of a lining epithelium (hence a "pseudocyst") within the dermis
- The cystic spaces begin as dermal clefts between collagen bundles and later coalesce to forms a single cystic space.
- The pseudocysts may occasionally have a synovial lining or a fibrous pseudocapsule.
- There is sometimes hyperplasia of the overlying epidermis.