Ganglion Cyst

a) Ganglions, Ganglion Cysts –

 Account for 60-70% of soft-tissue tumours of the hand.
 The disease is common in females in their third and fourth decades.
 Usually arise adjacent to tendons. May also be intraosseous or intratendinous


Aetiology (theories):

– Formed by herniation of the synovial lining in which a one-way valve mechanism is created
– benign tumors of synovial origin
– A rent in the joint capsule or tendon sheath allows leakage of synovial fluid, which irritates surrounding tissue. This local tissue reacts by forming a pseudocapsule and subsequent ganglion
– Mucoid degeneration of connective tissue, with breakdown products of collagen collecting in pools, which coalesce to form large cysts.

Usual Sites
• Dorsum of the wrist (70%): in this location the origin is Scapholunate ligament. The dorsal ganglia are usually painless and they are found between the EDC and the EPL tendons.
• Volar wrist (20%): Deriving their origin from the radiocarpal (2/3rd) or STT (1/3rd) joints.
• Dorsum of the distal interphalangeal (DIP) joint-mucous cyst
• Volar aspect of a digit at the metacarpal phalangeal flexion crease (volar retinacular ganglion cyst). Arise from the A1 or A2 pulley of the flexor tendon sheath

Cyst fluid is gelatinous (apple jelly-like) with a high concentration of hyaluronic acid.
Microscopy: ganglia develop in stages as follows
1. First stage characterised by large number of spheroidal cells that are closely packed with a periphery of spindle cells
2. The second stage consists of spheroidal cells and spindle cells but with a central cavity filled partly with secretion from the spheroid cells.
3. Third stage, here the ganglion is well developed with a smooth wall resembling synovial membrane of joints. The walls of the larger cyst are poorly vascularised and the vessels show fibrosis of their wall suggesting a vascular aetiology for the development of these cysts.

Clinical Features:
Dorsal ganglion
• The mass is compressible, subcutaneous, transilluminating, slightly mobile, and without skin changes.
• Wrist extension often elicits pain at the site.
• Small dorsal ganglions may be palpable only in full wrist flexion.
• Occult ganglions are not palpable but may be quite painful.
• wrist pain, tenderness, and interference with activity

Volar ganglion:
• The mass is usually palpable between the radial artery and the flexor carpi radialis (FCR) tendon, or
• Adjacent to the scaphoid tubercle in the anatomic snuffbox or more distal in the palm.
• May arise ulnarly from the pisotriquetral joint and are palpable adjacent to the flexor carpi ulnaris (FCU) tendon.
• May compress the palmar cutaneous branch of the median nerve, median nerve or the deep branch of the ulnar nerve

Volar Retinacular Ganglion Cyst:
• Present as a small, very firm, minimally mobile mass near the proximal digital crease or metacarpophalangeal joint.
• do not move with flexor tendon excursion
• They are painful only when gripping a firm surface.
• Volar retinacular ganglions do not cause digital triggering, nor are they associated with trigger digits
• Can compress the digital nerve causing sensory disturbance.

Mucous Cyst:
• Gradually enlarging subcutaneous mass develops over the dorsal DIP joint.
• The lesion is firm and minimally mobile and can be transilluminated
• Lies typically lateral to midline, being displaced by the extensor tendon.
• Associated with osteoarthritis
• May rupture and get infected
• Nail deformity may develop from pressure on the germinal matrix.

Ganglions maybe associated with tendons, they are typically located in the dorsal wrist, extensor apparatus or the FCR in the volar wrist

Intraosseous ganglions of the hand and wrist: most common in the scaphoid and lunate.
On X-rays: The lesions appear radiolucent with a sclerotic border and frequently contact a joint surface without causing cortical expansion. Diagnosis is mainly of exclusion.



DD for dorsal wrist ganglion:
1. Ganglion of tendon sheath, giant cell tumor of tendon sheath, tenosynovitis of inflammatory or infectious origin, or an extensor digitorum brevis manus muscle belly.
2. The proximal pole of the scaphoid may be prominent dorsally in cases of dorsal intercalated segment instability,
3. The proximal pole of the lunate may be prominent in volar intercalated segment instability.
4. A firm mass more radial and slightly more distal may be an osteophyte from scaphotrapezial arthritis.
5. A compressible mass that decreases in size with elevation of the wrist may be a venous aneurysm

DD for volar ganglion:
1. Aneurysms of the radial or ulnar arteries
2. Intraneural cysts.

DD for volar retinacular ganglion cyst:
1. epidermoid inclusion cyst,
2. giant cell tumor of tendon sheath,
3. foreign body granuloma,
4. lipoma
5. Neurilemoma.

DD for mucous cyst:

1. Heberden’s node
2. Gout
3. Giant cell tumor of tendon sheath.

Diagnosis: is mainly clinical. USG and MRI also help in establishing a diagnosis

Wrist Arthroscopy has potential advantages in both diagnosing and treating an occult dorsal ganglion that is intra-articular and therefore visible from within the radiocarpal joint, and also provides information about other causes of dorsal wrist pain, such as synovitis, chondromalacia,
and scapholunate ligament tears


Treatment
Historical folk medicine has mentioned rupture with a mallet or Bible, methods that need not be considered except for their historical interest
i. cyst puncture and aspiration (High recurrence)

ii. Excision

Dorsal ganglia:



• Surgical treatment can be performed with the use of intravenous regional (Bier block) anesthesia,
• A transverse incision in Langer’s lines leaves a less noticeable scar than a longitudinal one
• The ganglion lies between the second and fourth dorsal extensor compartment
• Dissection is carried down to the joint capsule.
• When they are properly excised with a swath of joint capsule surrounding the stalk of the cyst, recurrence rates are less than 10% for dorsal cysts, and as high as 20% for volar cysts.
• It is important to maintain the overall integrity of the capsule and to not create secondary instability
• This lower recurrence rate may be due to the removal of a valvular mechanism or microcysts in the surrounding capsular tissue.

Volar Ganglia:
• Cyst puncture and aspiration is not recommended due to proximity to radial artery
• Surgical excision is preferred: Longitudinal incision just radial to the FCR tendon
• Branches of the lateral antebrachial cutaneous nerve and superficial radial nerve must be protected.
• The radial artery is carefully dissected free and gently retracted radially.
• If this dissection is difficult due to adherence of the cyst wall to the artery the technique of Lister and Smith maybe used
• According to Lister and Smith: one wall of the cyst is left attached to the artery while the remainder of the cyst and the stalk are excised.
• Ulnar sided volar ganglions are approached with a longitudinal incision along the radial border of the FCU tendon.


Volar Retinacular Ganglion Cyst:
• The mass is excised with a small window of tendon sheath, which is not repaired
• The neurovascular bundle is preserved.

Mucous cyst:
• Excision of the stalk of the cyst, removal of the dorsal capsule and synovium, and debridement of dorsal osteophytes to minimize the risk of recurrence.
• An H-shaped incision with the transverse limb over the DIP joint and the longitudinal
limbs in the midaxillary line
• In an open draining sinus, a rotational flap is done by triangulating the cyst into the incision.

Curettage and bone grafting is done for established ganglion cyst of bone.

Complications:
• Recurrence
• Painful neuroma if the superficial branch of the radial nerve or palmar cutaneous branch of the median nerve is involved
• Intercarpal instability if the intercarpal ligaments are accidentally excised
• Injury to radial artery in the volar radial wrist, ulnar neurovascular injury in the ulnar volar wrist, and digital neurovascular injury in the region of the palmar digital crease.

NB: Turret exostosis – Traumatic subperiosteal haemorrhage in the phalangeal bones that leads to extraperiosteal new bone formation. Excision after the bone matures is curative.