Digital mucous cysts (DMCs), are also known as myxoid cysts.
DMCs are benign cystic lesions that typically occur on the dorsal aspect of the distal interphalangeal (DIP) joints or the proximal nail fold of the fingers and toes.
DMC commonly presents as a superficial, dome-shaped, shiny, cystic nodule located near the distal interphalangeal joint on the dorsum of the fingers.
Benign ganglion cysts of the digits, typically located at the distal interphalangeal joints or in the proximal nail fold.
They usually occur on the hands, although they uncommonly occur on the toes.
Etiology is uncertain but may involve mucoid degeneration.
Usually asymptomatic and do not require treatment.
Cysts probably arise from mucoid degeneration of connective tissue and that this process, in most cases, involves communication with the adjacent DIP joint and possible coexistence of osteoarthritis.
Osteoarthritis is common at the site of the cysts.
The cyst is commonly diagnosed clinically based on the appearance and the history of intermittent discharge of a mucoid substance.
DMC is more common in people with osteoarthritis and in women.
Such cysts are filled with a clear, viscous, jelly-like fluid rich in hyaluronic acid.
DMCs are often associated with underlying osteoarthritis of the DIP joint.
Some cases arise independently from the joint due to metabolic derangements in fibroblasts.
DMCs present as solitary, clear, or flesh-colored nodules.
DMCs can be asymptomatic or cause pain, tenderness, or nail deformities due to pressure on the nail matrix.
DMCs are typically diagnosed based on their characteristic appearance and location.
Imaging such as MRI can be used to confirm the diagnosis and assess the relationship with the joint.
Treatment options include both conservative and surgical approaches.
Conservative treatments include repeated needling, cryotherapy, and sclerotherapy with agents like polidocanol.
Surgical options, have higher cure rates and include complete excision of the cyst.
Often other procedures are combined addressing underlying joint pathology, such as osteophyte removal or arthroplastic resection.
Surgical deroofing combined with trichloroacetic acid application, have also been explored with promising results.
The choice of treatment depends on the severity of symptoms, the presence of underlying joint disease, and patient preference.
Surgical excision remains the most definitive treatment with the lowest recurrence rates.
Transillumination is a quick and easy way to diagnose DMC.