Digital Myxoid Cyst and Ganglion

Abstract

Synonyms include mucinous cyst and synovial cyst.

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Synonyms

Synonyms include mucinous cyst and synovial cyst.

Clinical Description

A digital myxoid cyst is a translucent, blue, cystic papule on the digits, especially around the dorsal distal interphalangeal joint or phalanx. A ganglion is a subcutaneous cystic nodule that moves with the attached tendon [1, 2].

Etiology and Pathophysiology

Two subtypes of digital myxoid cysts are seen:

• 1. Traumatic herniation of synovial sac, with extrusion of mucin into dermis

• 2. Overproduction of mucin (hyaluronic acid) by fibroblasts, with underproduction of collagen (focal mucinosis)

A ganglion involves herniation of the synovial lining of a tendon or joint [3].

Histopathology

Mucinous deposits occur in multiple clefts or coalesce into a large cystic mass. No cyst lining is seen in the dermis but a stalk may connect to the joint space.

Differential Diagnosis

Mucinous cyst and ganglion have a distinctive clinical appearance. Eccrine and apocrine hidrocystomas are much smaller and are located periorbitally. Giant cell tumor of the tendon sheath and exostosis are solid, not cystic.

Therapy

• 1. Drainage of mucin followed by injection with triamcinolone acetonide, 4–10 mg/ml. and compression

• 2. Hand surgery with exploration of joint or tendon and excision of cystic pedicle in refractory cases [4, 5]

Prognosis

A digital myxoid cyst or ganglion is stable, with little tendency for spontaneous resolution and no tendency for malignant degeneration.

Figs. 33.1 and 33.2

Digital mucinous cyst. This is a firm, translucent, blue cystic papule overlying the distal interphalangeal joint

Fig. 33.3

Giant cell tumor of the tendon sheath. This is a firm nodule that usually occurs at the distal phalanx. It can be confused with a digital mucinous cyst

Fig. 33.4

Exostosis. This is a bony overgrowth produced by trauma, with reactive hyperplasia of the periosteum and underlying bone

Fig. 33.5

Ganglion of the volar wrist. These lesions have been treated by smashing with the Bible, although surgical techniques have lower recurrence rates

Fig. 33.6

Mucocele of inner lip. This results from a blocked salivary gland, with retention of mucus