Objectives:Upon the completion of this CME article, the reader will be able to
1. Identify the sonographic appearance of the pertinent musculoskeletal anatomy of the normal hand and wrist.
2. Identify the sonographic appearance of benign soft tissue tumors.
3. Describe the risk factors for carpal tunnel syndrome and identify it sonographically.
Benign Soft Tissue Tumors
There are many different types of benign soft tissue tumors of the hand, including ganglions, giant cell tumors of the tendon sheath, hemangiomas, glomus tumors and nerve tumors. Ganglions are the most common soft tissue tumor of the hand and account for 70% or more of masses. The pathogenesis of these mucin-filled, fibrous-lined cysts is unknown, but at least 10% of the patients have a history of previous trauma, leading to the possibility that trauma is a cause, at least in some cases. Also, it recently has been reported that ganglions are associated with internal derangements of the wrist, particularly, scapholunate ligament tears. Ganglions are more common in women than in men and usually occur between 10 and 40 years of age. Most ganglions present as firm masses that either may be asymptomatic (especially when large) or might cause pain and tenderness (especially when small). At sonography, ganglions are non-compressible, well defined and anechoic with acoustic enhancement. Occasionally, debris is present within the cyst, and they may be multiloculated as well. The most common location for a ganglion is at the dorsum of the wrist, at the level of the scapholunate ligament. This type of ganglion actually arises from the radio-carpal joint capsule, where it attaches to the scapholunate ligament. The cyst penetrates the ligament to communicate with the scapholunate joint through a tortuous duct-like system. Dorsal wrist ganglions may be very small and non-palpable (occult) or may be located remotely from the scapholunate ligament due to a long pedicle (figures 1 and 2).
Volar (palm side) wrist ganglions represent approximately 18% to 20% of wrist ganglions, and are usually located at the level of the radioscaphoid or scaphotrapezial joint. The former is located between the flexor pollicis longus and abductor pollicis longus tendons and the latter is palpable over the scaphoid tubercle and often surrounds the flexor carpi radialis tendon.
Another common site for a ganglion is the flexor tendon sheath at the level of the A1 pulley (metacarpophalangeal joint) or A2 pulley (proximal phalanx). Flexor tendon sheath ganglions (also called volar retinaculum ganglion cysts) represent approximately 10% to 12% of wrist ganglions. This type of ganglion penetrates through the pulley and is tethered; thus, it does not move with flexor tendon motion.
A much less common location for a ganglion is the distal interphalangeal joint. This type of ganglion is referred to as a mucous cyst and is associated with osteoarthritis of the distal interphalangeal joint. Usually it is located to one side of the terminal tendon between the dorsum of the distal joint and the nail bed. Nail deformities often occur in association with this type of cyst.
Asymptomatic wrist ganglions are treated conservatively. Symptomatic ganglions can be injected with steroids (although there is an increased frequency of recurrence) or they may be surgically resected.
Giant cell tumor (GCT) of the tendon sheath, also called nodular synovitis, is the second most common hand tumor. It is a localized extra-articular form of pigmented villo-nodular synovitis and essentially is considered a benign proliferative disorder of the synovium. GCT of the tendon sheath is more common in women than in men and usually occurs between 20 and 40 years of age. Patients usually present with a painless, slowly enlarging, firm nodule, but approximately 20% of patients complain of pain or tenderness. Treatment is surgical resection. Most giant cell tumors of the tendon sheath are located along the volar surface of the thumb, index, and middle fingers at the distal interphalangeal joint level, but dorsal and more proximal involvement of the flexor tendon sheath is not uncommon. At sonography, these tumors are hypoechoic and solid. They have well defined margins, but may have an irregular shape. Occasionally pressure erosions can be seen in the adjacent bones. GCTs are intimately related to tendons, and in some cases may partially surround them (figure 3). Because they arise from the sheath and not from the tendon, they do not move with tendon motion. Giant cell tumors almost always have detectable internal vascularity on color and power Doppler and are sometimes hypervascular, as seen with high resolution transducers and Doppler.
Hemangiomas represent approximately 10% of benign hand tumors. They are found with equal frequency in men and women and occur most commonly in young adults. Patients usually present with a slowly growing, painless mass that has the consistency of soft rubber. The overlying skin may be discolored (raspberry appearance) and thinned. At sonography, hemangiomas are solid and either hypoechoic or hyperechoic. Occasionally, phleboliths (a calculus or stone within a vein) may be detected. Because hemangiomas have a tendency to infiltrate soft tissues, their margins may be somewhat ill defined. Detectable vascularity is variable but some hemangiomas may appear hypervascular on color Doppler examination. Hemangiomas may be treated conservatively or surgically excised.
Glomus tumors represent less than 5% of all hand tumors. They arise from the neuromyoarterial apparatus in the dermis and are located either in the subungual region (beneath the nail) or the volar surface of the fingertip. Patients with these tumors are exquisitely hypersensitive to cold and touch and experience paroxysmal pain. There also may be a bluish discoloration of the nail bed when the tumor is subungual in location. Surgical excision is required to alleviate symptoms. At sonography, glomus tumors are hypoechoic and solid but may show slight acoustic enhancement. Although they may be only a few millimeters in size, the margins of these tumors are well defined. Subjacent cortical bony erosion may also be noted. Glomus tumors appear very hypervascular by color Doppler sonography.
There are many different types of neurogenic tumors that can involve the upper extremity, but schwannomas are the most common among these. They arise from the Schwann cell and are eccentric in relation to a peripheral nerve. Schwannomas occur with equal frequency in men and women, and are frequently located along the flexor surface of the forearm or hand. The peak incidence is between 30 and 60 years of age. Schwannomas usually present as painless masses, but rarely can present as a neurologic deficit.
Neurofibromas are benign tumors that arise within the nerve fasciculi and are inseparable from normal nerve tissue. As compared with schwannomas, they occur in a slightly younger age group (20 to 30 years). They are equal in incidence in men and women, and most present as slow growing, painless lesions. Traumatic neuromas are histologically similar, but arise at the severed end of a proximal peripheral nerve stump within 1 to 12 months after transection. Only neuromas arising from sensory nerve fibers are painful.
At sonography, neurogenic tumors may appear hypoechoic and show slight acoustic enhancement. Their margins are well defined and the nerve of origin can frequently be seen entering and or exiting the tumor. A traumatic neuroma is located at the end of the severed nerve; whereas a Schwannoma is eccentric in relation to the involved nerve and a neurofibroma is central in relation to the involved nerve. This may be difficult to determine at sonography in smaller lesions. Neurogenic tumors are treated by surgical excision; however, neurofibromas are very difficult to excise and attempted removal may result in a neurological deficit.
Lipomas are benign tumors that can occur in the hand. Most are subcutaneous or intramuscular, but these lesions have been reported to arise in the carpal tunnel, deep palmar space, and in tendon sheaths. Lipomas usually present as a soft or rubbery painless mass, however, if they arise in the deep palmar space or are adjacent to a major nerve, symptoms may occur secondary to nerve compression. If a lipoma is large, liposarcoma must be ruled out, and therefore, should be removed surgically for pathologic evaluation. On the other hand, small asymptomatic lipomas are usually managed conservatively. At sonography, lipomas are well-demarcated lesions that may be hypoechoic, hyperechoic, or isoechoic. Depending on their location, they may assume an elongated shape.
Epidermal inclusion cysts result from traumatic implantation of epithelial cells into underlying soft tissues. These lesions occur most commonly in the fingertips and present as a firm, slow-growing, and usually painless masses, although a minority of patients may complain of pain. At sonography, epidermal inclusion cysts are well-circumscribed lesions that are homogeneous, and somewhat hyperechoic. Epidermal inclusion cysts may be surgically excised or managed conservatively.
Carpal Tunnel Syndrome
Carpal tunnel syndrome (CTS) is the most common compressive peripheral neuropathy of the upper extremity and is being diagnosed with increasing frequency in patients with occupations that require repetitive motion or produce mechanical stress on the median nerve. Examples of such occupations include typists, transcriptionists, musicians, jackhammer operators, and carpenters, etc. However, other risk factors unrelated to occupation, including pregnancy, rheumatoid arthritis, chronic renal failure, diabetes mellitus, amyloidosis, and tenosynovitis have also been associated with carpal tunnel syndrome.
Patients typically present with pain and parasthesias in the distribution of the median nerve, often worse at night and reproducible with certain repetitive activities. Whereas electromyography (EMG) has long been considered the gold standard for the diagnosis of CTS, it is invasive, very operator dependent, and the result may be normal in the presence of nerve compression. Recently, the in vitro and in vivo sonographic characteristics of the normal and abnormal median nerve were elucidated by Lee, et al. Measurements of the median nerve were obtained from axial images using the wrist crease as an anatomic landmark. The cross-sectional area of the median nerve was calculated using the equation for an ellipse (area = π (D1xD2)/4). (D1 and D2 refer to the anteroposterior and transverse dimensions of the median nerve). Lee, et al showed that the mean cross-sectional area of the normal median nerve was 8.3 mm2 in men and 9.3 mm2 in women. In patients with CTS, the median nerve was noted to be enlarged. When EMG findings were correlated with median nerve cross-sectional area, Lee, et al noted that a cross-sectional measurement of 15mm2 or greater corresponded to a moderately-to-severely abnormal EMG that indicated the need for surgical intervention (carpal tunnel release). A cross-sectional area less than 15mm2 corresponded to a normal-to-mildly abnormal EMG that indicated conservative management (such as splinting, non-steroidal anti-inflammatory drugs, warm soaks, and steroid injections). Based on these results, Lee, et al recommend ultrasound as the first step in the diagnostic evaluation of the patient who clinically is suspected of having carpal tunnel syndrome.
As can be seen, sonography is very useful in diagnosing pathologic conditions of the hand and wrist. Even though many of the described conditions have similar sonographic appearances, knowledge of the patient’s sex, age, clinical history, and signs and symptoms, and an understanding of the most common location and sonographic features of these lesions will often assist in narrowing the differential diagnosis.
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About the Author
Sharlene A. Teefey, M.D. is currently an Associate Professor of Radiology at the Mallinckrodt Institute of Radiology at Washington University School of Medicine in St. Louis Missouri. She is a member of numerous societies and organizations including the American College of Radiology, the Society of Radiologists in Ultrasound, and the American Institute of Ultrasound in Medicine.
She is a reviewer of manuscripts for Radiology, the American Journal of Roentgenology, and Radiographics. She has more than 45 publications in peer review medical journals and has been a speaker at numerous institutions and conferences across the country.
1. There are many different types of benign soft tissue tumors of the hand, but the most frequent is
A. nerve tumors
B. giant cell tumors of the tendon sheath
C. ganglion cysts
D. glomus tumors
2. Regarding ganglion cysts,
A. At least 50% of patients have a history of previous trauma.
B. They account for about 90% or more of masses of the hand and wrist.
C. They usually occur between the ages of 40 and 60.
D. The pathogenesis of these mucin-filled, fibrous-lined cysts is unknown.
E. Ganglions are more common in men than in women.
E. not associated with having debris present within the cyst
4. The most common location for a ganglion is at the dorsum of the wrist at the level of the
A. radioscaphoid joint
B. scapholunate ligament
C. scaphotrapezial joint
D. A1 pulley (metacarpophalangeal joint)
E. A2 pulley (proximal phalanx)
5. Volar (palm side) wrist ganglions are usually located
A. at the level of the proximal interphalangeal joint
B. at the level of the distal interphalangeal joint
C. on the dorsum of the wrist at the level of the scapholunate ligament
D. in the subungual region
E. at the level of the radioscaphoid joint
6. The type of ganglion cyst that is referred to as a mucous cyst and is associated with osteoarthritis of the joint is located at the ________ joint.
C. proximal interphalangeal
D. distal interphalangeal
7. Regarding giant cell tumor (GCT) of the tendon sheath, all of the following are true EXCEPT
A. They are more common in men than in women.
B. They usually occur between 20 and 40 years of age.
C. Patients usually present with a painless, slowly growing, firm nodule.
D. They are the second most common hand tumor.
E. They are considered a benign proliferative disorder of the synovium.
8. Regarding giant cell tumors of the tendon sheath
A. At sonography, these tumors are hyperechoic and cystic.
B. Because they arise from the sheath and not from the tendon, they do not move with tendon motion.
C. At sonography, they have poorly defined margins.
D. They almost never have detectable internal vascularity on color and power Doppler.
E. At sonography, they are essentially round in shape and never appear irregular.
A. occur most commonly in young adults.
B. represent approximately 70% of benign hand tumors.
C. are found more often in men than in women.
D. usually present as fast growing, painful masses.
E. usually have the consistency of a hard rock.
10. The type of hand tumor that may be associated with discolored overlying skin (raspberry appearance) is a (an)
A. giant cell tumor
D. epidermal inclusion cyst
11. Regarding glomus tumors, all of the following are true EXCEPT
A. Patients with these tumors are exquisitely hypersensitive to hot temperatures but they usually have no pain.
B. They are located either in the subungual region (beneath the nail) or the volar surface of the fingertip.
C. There may be a bluish discoloration of the nail bed when the tumor is subungual in location.
D. At sonography, they are hypoechoic and solid but may show slight acoustic enhancement.
E. They appear very hypervascular by color Doppler sonography.
12. Regarding schwannomas, which of the following statements is true?
A. The peak incidence is between 10 and 30 years of age.
B. They are the second most common neurogenic tumor.
C. They occur more commonly in men than in women.
D. They are eccentric in relation to a peripheral nerve.
E. They usually present as painful masses, but neurologic deficits essentially do not occur.
13. Regarding neurofibromas
A. They are inseparable from normal nerve tissue.
B. They are malignant tumors that arise within the nerve fasciculi.
C. They occur in an older age group of 50 to 60 years.
D. They are more common in women than in men.
E. Most present as fast growing, painful lesions.
14. All of the following statements are true EXCEPT
A. At sonography, neurogenic tumors may appear hypoechoic and show slight acoustic enhancement.
B. At sonography, the margins of neurogenic tumors are well defined and the nerve of origin can frequently be seen entering and or exiting the tumor.
C. A traumatic neuroma is located at the end of the severed nerve.
D. Neurofibromas are very difficult to excise and attempted removal may result in a neurological deficit.
E. A Schwannoma is central in relation to the involved nerve.
15. Regarding lipomas, all of the following statements are true EXCEPT
A. They are benign tumors.
B. They are nearly always large; therefore, if they are small, they should be removed surgically to rule out liposarcoma.
C. Most are subcutaneous or intramuscular, but have been reported to arise in the carpal tunnel, deep palmar space, and in tendon sheaths.
D. They usually present as a soft or rubbery painless mass, however, if they arise adjacent to a major nerve, nerve compression symptoms may occur.
E. At sonography, they are well-demarcated lesions that may be hypoechoic, hyperechoic, or isoechoic.
16. Regarding epidermal inclusion cysts
A. At sonography, they are poorly circumscribed lesions that are non-homogeneous, and somewhat hypoechoic.
B. They occur most commonly on the dorsum of the wrist.
C. They present as soft, fast-growing, and usually painful masses.
D. They result from traumatic implantation of epithelial cells into underlying soft tissues.
E. They can only be surgically excised; conservative management is of no benefit.
17. Regarding carpal tunnel syndrome,
A. It is an uncommon compressive peripheral neuropathy of the upper extremity.
B. The diagnosis related to occupation appears to be less common than previously believed.
C. Risk factors unrelated to occupation include such entities as pregnancy, rheumatoid arthritis, and amyloidosis.
D. It is being diagnosed with increasing frequency in patients with occupations that produce mechanical stress on the radial nerve.
E. It is has been discovered that occupations that require repetitive motion also require an underlying genetic factor in order for the syndrome to develop.
18. Patients with carpal tunnel syndrome typically present with parasthesias in the distribution of the ________ nerve.
19. Lee, et al showed that the mean cross-sectional area of the normal median nerve was
A. 6.7 mm2 in men and 7.6 mm2 in women.
B. 7.6. mm2 in men and 6.7 mm2 in women.
C. 8.3 mm2 in men and 9.3 mm2 in women.
D. 8.7 mm2 in men and 7.6 mm2 in women.
E. 9.3 mm2 in men and 8.3 mm2 in women.
20. When EMG findings were correlated with median nerve cross-sectional area, Lee, et al noted that a cross-sectional measurement of _____ mm2 or greater corresponded to a moderately-to-severely abnormal EMG.