You are in: eMedicine Specialties > Orthopedic Surgery > NEOPLASMS Mucous CystArticle Last Updated: Feb 5, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Divya Singh, MD, Hand and Orthopedic Surgeon, Department of Orthopedic Surgery, Group Health Permanente Divya Singh is a member of the following medical societies: American Academy of Orthopaedic Surgeons Coauthor(s): A Lee Osterman, MD, Director of Hand Surgery Fellowship, Director, Philadelphia Hand Center; Director, Professor, Department of Orthopedic Surgery, Division of Hand Surgery, University Hospital, Thomas Jefferson University Editors: Miguel A Schmitz, MD, Consulting Surgeon, Department of Orthopedics, Klamath Orthopedic and Sports Medicine Clinic; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Sean P Scully, MD, PhD, Professor, Department of Orthopedics, University of Miami; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; Harris Gellman, MD, Consulting Surgeon, Broward Hand Center, Voluntary Clinical Professor of Orthopedic Surgery and Plastic Surgery, Departments of Orthopedic Surgery and Surgery, University of Miami School of Medicine Author and Editor Disclosure Synonyms and related keywords: mucoid cyst, synovial cyst, myxoid cyst, myxomatous cutaneous cyst INTRODUCTIONSection 2 of 12
  Mucous cysts (see Image 1) are ganglions of the distal interphalangeal joint (DIP) of the hand or of the toes. They have had several names, including mucoid cysts, synovial cysts, myxoid cysts, and myxomatous cutaneous cysts.1, 2, 3, 4, 5, 6, 7, 8 History of the ProcedureTreatment options in the past have included aspiration, electrocautery, chemical cautery, steroid injection, and various types of surgical excision. Surgery currently is considered the definitive treatment for mucous cysts. ProblemApart from the cosmetic deformity, patients with mucous cysts may note chronic drainage, infection,9 and pain. The pain may be secondary to the arthritic joint, as well as to the cyst itself. FrequencyMucous cysts are most common in the fifth through seventh decades of life. Mucous cysts are more common in women, who constitute roughly 70% of the patients. EtiologyThe precise etiology of mucous cysts is unclear; theories include synovial herniation, extensor retinacular metaplasia, myxomatous degeneration, and excess hyaluronic production by fibroblasts. PathophysiologyMucous cysts are associated with degenerative joint disease of the DIP joint (see Image 2) in 60-80% of cases. Studies have shown a pedicle between the cyst and the DIP joint capsule.10, 11, 12 ClinicalOn physical examination, the cyst is located between the DIP extensor crease and the eponychium, lateral to the midline, measuring up to 15 mm (averaging 7 mm). The overlying skin can be thick or thin, and the patient may report sporadic drainage of the viscous fluid. Some erythema may surround the ganglion. Eventually, the cyst may result in a grooved deformity of the nailbed, or a nail groove may be present before the cyst is visible. Patients present to their physicians because of the deformity, although some may complain of discomfort.13, 14, 15, 10, 12, 16 Differential diagnoses include Heberden nodes or rheumatoid nodules, epidermoid inclusion cyst, Dupuytren knuckle pad, xanthoma, giant cell tumor of the tendon sheath, and gout. INDICATIONSSection 3 of 12
Surgical excision is indicated in the presence of active infection, drainage, or pain. Patients also may complain of nailbed deformity or extensor lag. RELEVANT ANATOMYSection 4 of 12
See Surgical therapy. CONTRAINDICATIONSSection 5 of 12
There are few contraindications to surgery. Even if the patient has medical comorbidities with concomitant risks with anesthesia, surgery can be performed with a digital block. WORKUPSection 6 of 12
Imaging Studies
Histologic FindingsGrossly, mucous cysts are cystic, smooth, translucent masses with viscous fluid. Histologically, under light and scanning microscopy, mucous cysts share the same ultrastructure as other soft-tissue ganglions. Under light microscopy, ganglions have a smooth collagenous lining. Using scanning electron microscopy, crisscrossing layers of collagen are identified, with areas of elevations hypothesized to be multifunctional mesenchymal cells. No major degenerative or inflammatory changes are seen, nor are bursal or synovial endothelial cells. Multiple cavities may be found coalescing into a larger space. TREATMENTSection 7 of 12
Medical therapyTreatment options in the past have included aspiration, electrocautery, chemical cautery, steroid injection, and various types of surgical excision. Most of these procedures are associated with significant recurrence rates, although these tend to be lower than those of carpal ganglions. Aspiration of digital ganglions was found to have a 65-69% success rate, compared with 27-45% for carpal ganglions. One caveat with aspiration is the risk of infection. In fact, infections of the cyst and subsequently the joint can occur from spontaneous breakdown of the cyst or from iatrogenic aspiration. Promptly treat such infections, as they often lead to septic arthritis and osteomyelitis with disastrous complications. Some early authors proposed that low-voltage radiation is associated with a lower recurrence rate than surgery.17, 18, 19, 20, 21, 22 Surgical therapySurgery currently is considered the definitive treatment for mucous cysts. Surgery is recommended in the presence of ongoing pain, recurrent infection, or chronic drainage. Based on surgeon's preference and locations of the cyst, various surgical incisions can be used, including an H, T, U, or a transverse curving incision shape. After the skin is incised, the dissection is continued around the cyst, tracing the stalk down to the joint. Care must be taken to avoid damaging the terminal extensor tendon, germinal matrix, and the terminal portions of the neurovascular bundles. Depending on the intraoperative findings, a synovectomy, osteophyte resection, and debridement may be performed. A disrupted terminal extensor tendon (whether iatrogenic or cyst related) should be repaired to prevent subsequent extensor lag.8, 18, 20, 23, 24, 25, 26 In the event of significant DIP joint arthritis and pain, an arthrodesis can be performed at the same surgery. Chen advocated radical excision of the attenuating skin overlying the cyst, as this can contain satellite ducts and lakes of mucoid degeneration. The surgeon can obtain the patient's consent preoperatively for a skin graft if skin excision leaves extensor tendon or joint exposed. Rotation flaps have been utilized to compensate for excised or thinned skin overlying the cyst. The decision to use skin graft, a rotational flap, or close primarily is largely surgeon dependent. In the authors' experience, most incisions can be closed primarily without the need for further coverage procedures.27, 28, 29 Preoperative detailsPreoperative planning is limited, as much of the procedure is based on intraoperative findings. In the presence of significant arthritic pain, the patient consent can be obtained for a DIP joint arthrodesis. This can be done with single screw fixation (eg, an Acutrak or Herbert screw) or with Kirschner wires (K-wires) and cables, based on surgeon's preference. The relevant factors to remember preoperatively are to remove the osteophyte and obtain adequate skin coverage postexcision. Patient consent should be obtained for skin graft or rotation flap if needed. Intraoperative detailsStudies have shown the necessity of excising not only the cyst, but also the underlying DIP osteophyte. The recurrence rate with both cyst and osteophyte excision is 3-12%, compared to a 25-50% recurrence rate with cyst excision alone. Care must be taken to avoid injury to the germinal matrix and to prevent further nail deformity. One study described treatment of fingernail deformities secondary to mucous cysts with removal of the osteophyte only, without excision of the ganglion or skin. In this study of 20 ganglion cysts, the ganglion did not recur in any patients and 2 nails had residual grooves. Postoperative detailsUnless an extensor tendon repair or some other procedure requiring joint immobilization is involved, only a light dressing is needed postoperatively. Gentle active range of motion is allowed, and sutures usually are removed after 2 weeks. COMPLICATIONSSection 8 of 12
Infection is a common complication of mucous cysts, either preoperatively or postoperatively. For that reason, prophylactic antibiotics are used intraoperatively and for 3 days postoperatively.30, 9 Complications from surgery include extensor tendon disruption, recurrence, and nail deformity from injury to the germinal matrix. Other potential risks include persistent pain, swelling, stiffness, and infection. If a patient continues to have pain secondary to degenerative joint disease, a DIP joint arthrodesis may be performed later. OUTCOME AND PROGNOSISSection 9 of 12
The recurrence rate with both cyst and osteophyte excision is 3-12%, compared with a 25-50% recurrence rate with cyst excision alone. FUTURE AND CONTROVERSIESSection 10 of 12
Studies have shown the necessity of excising not only the cyst, but also the underlying DIP osteophyte (see Intraoperative details). MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
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