Digital Mucous Cyst – 3 Interesting Facts
- Digital mucous cysts (DMCs) present as smooth dome-shaped papules, which may be compressible. DMCs are usually located on the dorsal fingers, near the proximal nail fold. Less often, DMCs occur on the toes.
- DMCs are benign, and no treatment is required.
- DMCs usually persist indefinitely, but spontaneous resolution can transpire.
Introduction
Etiology and Risk Factors
- The pathogenesis of DMCs is not fully understood. Evidence suggests they are not true neoplasms but instead are the result of degenerative changes of trauma and aging (e.g., osteoarthritis) at the distal interphalangeal joint. This theory is supported by studies (e.g., surgical dissections and dye studies) that show connections between the joint space and digital mucous cysts. The material in the cysts, like fluid in joints, is composed chiefly of hyaluronic acid that appears clear, with a jelly-like consistency.
- DMCs usually arise in older adults.
Workup
Physical Examination
- The clinical appearance and distribution are often characteristic of digital mucous cysts (DMCs).
- DMCs are usually asymptomatic but can be tender.
- DMCs are usually located on the dorsal fingers, near the proximal nail fold. Less often, DMCs occur on the toes.
- DMCs present as smooth dome-shaped papules, which may be compressible.
- DMCs may be skin-colored or translucent.
- Less common variants may be ulcerated, inflamed, or verrucous.
- Lesions over the proximal nail fold may produce a linear depression or groove in the nail plate.
Imaging Studies
- The cystic nature of DMCs can often be confirmed by compression or via transillumination.
Diagnostic Procedures
- The diagnosis of DMCs can be confirmed by making a small incision with a no. 11 scalpel blade, with expression of a clear, viscous, and gelatinous fluid. However, care should be taken to ensure the joint space does not become infected.
- Rare cases require a shave or punch biopsy for diagnosis. The histologic findings are diagnostic. Again, care should be taken to ensure the joint space does not become infected.
Treatment
Approach to Treatment
- DMCs are benign, and no treatment is required.
Drug Therapy
- Intralesional triamcinolone can be used but with variable success.
Treatment Procedures
- Surgical excision of the cyst is often used, but ablation of the connection to the joint space is required.
- Shave removal of the cyst, with cauterization of the base by electrodessication, or with use of a chemical agent, such as phenol, may be used.
- DMCs can also be treated by supplying the patient with sterile, 27-gauge needles and with instructions to puncture the cyst and forcibly express the contents. This action may be repeated as often as necessary.
- Less common treatment modalities include carbon dioxide laser ablation and cryosurgery.
References
1.Böhler-Sommeregger K, Kutschera-Hienert G. Cryosurgical management of myxoid cysts. Journal of dermatologic surgery and oncology. 1988;14(12):1405-1408.
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2.Karrer S, Hohenleutner U, Szeimies RM, Landthaler M. Treatment of digital mucous cysts with a carbon dioxide laser. Acta dermato-venereologica 1999;79(3):224-225.
