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Clinical case: Glomus tumor of the hand misdiagnosed as carpal tunnel syndrome
In this article, we describe a case of a man who complains of stabbing pain in his right palm, together with the presence of a tender nodule. His diagnosis is a tumor, but which type exactly? Stick around to find out what types of tumors grow in places like the palms. You will also learn how the diagnosis was reached, the clinical presentation, and relevant anatomy.
| Carpal tunnel syndrome | It occurs when the median nerve is compressed as it travels through the carpal tunnel, resulting in nerve damage and muscle atrophy. The main causes include swollen tendon synovial sheaths or osteo-ligamentous changes. |
| Thenar eminence | It is the fleshy muscular area at the base of the thumb on the palmar surface of the hand, consisting of the abductor pollicis brevis, flexor pollicis brevis, and the opponens pollicis muscles. |
| Specific tests | 'Rule in a disease' - high true positive and low false positive rates |
| Sensitive tests | 'Rule out a disease' - high true negative and low false negative rates |
After reviewing this case you should be able to describe the following:
- What is meant by carpal tunnel syndrome, what causes the condition and how it is treated? Why, in this case, carpal tunnel syndrome could be confused with a tumor in the thenar eminence?
- What is meant by the thenar eminence, and what vessels and nerves supply the thenar eminence?
- What is meant by specificity versus sensitivity?
This article is based on a case report published in the Journal "Case Reports in Surgery" in 2015, by Caroline C. Jadlowiec, Beata E. Lobel, Namita Akolkar, Michael D. Bourque, Thomas J. Devers, and David W. McFadden.
Case description
History
The patient was a 55-year-old-male with complaints of a stabbing pain in his right palm. He described the pain as a sharp shooting pain that was present while working or handling objects. A neurologist had examined him previously, diagnosed carpal tunnel syndrome and started the patient on medication and physiotherapy, although nerve conduction studies done for the median nerve were normal.
Physical examination
The patient’s symptoms failed to subside and thus he was referred to an orthopedic surgeon. On examination, the right hand appeared normal. There was no discoloration or evidence of any abnormal swelling. However, there was a focal point of extreme tenderness in his right thenar eminence and exposure to cold also caused extreme pain. A small very tender nodule was identified on deep palpation of the thenar eminence.
Imaging and management
An ultrasound scan showed a highly vascularized solitary nodule of about 1 x 1 cm (Figure 1). A provisional diagnosis of hemangioma was made. A 2 cm incision was made over the nodule. Blunt dissection revealed a reddish blue nodule of approximately 1 x 1 x 1 cm in size, which was extirpated (Figure 2).
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Histopathology and final diagnosis
Histopathological analysis showed the nodule to contain multiple blood vessels that were surrounded by tumor cells with dense abundant cytoplasm and multiple nucleoli, indicative of a glomangioma (glomus body tumor) rather than a hemangioma.
Anatomical and surgical considerations
Glomus bodies are plentiful in the fingers and toes. They shunt blood away from the skin surface when exposed to cold temperature, reducing heat loss, but also the converse, which is to allow maximum heat flow to the skin in warm weather to facilitate body cooling. The glomus body is well innervated by sympathetic fibers and stimulation leads to near complete vasoconstriction of cutaneous vessels. The glomus bodies in the skin and elsewhere are atypical in that their “endothelial cells” are found in multiple layers of cells called myoepithelioid cells. The typical age at presentation of a patient with a glomus body tumor is 30-50 years of age, although the condition can occur at any age. Women are affected more than men. In the case described here, the patient was a male aged 55 years, which is unusual.
The patient with a glomus tumor seeks medical attention early because of the pain, but the mass is often too small to be identified on physical examination. However, a series of clinical tests that show severe pain upon probing, temperature sensitivity, and point tenderness have high specificity and sensitivity for the condition. The pain experienced by the patients on blunt probing is described as being similar to being struck by a hammer. Ultrasonography was done to determine the extent of the tumor. It indicated a solid, homogeneous, hypoechoic, hypervascular well-demarcated nodule of about one cm in size. The only treatment that has been advocated for a glomus nodule is complete surgical excision. Histopathology revealed the diagnosis of this tumor. The patient experienced complete pain relief with no recurrence (up to 18 months after surgery).
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Glomus bodies are innervated by the sympathetic nervous system. The sympathetic innervation of the hand is derived from the upper thoracic part of the thoracolumbar outflow through the stellate ganglion and the brachial plexus. The postganglionic sympathetic fibers eventually join the median and ulnar nerves to reach the fingertips (see Reynaud’s case for more details on the sympathetic innervation of the upper limb).
Explanations to objectives
Objectives
- What is meant by carpal tunnel syndrome, what causes the condition and how it is treated? Why, in this case, carpal tunnel syndrome could be confused with a tumor in the thenar eminence?
- What is meant by the thenar eminence, and what vessels and nerves supply the thenar eminence?
- What is meant by specificity versus sensitivity?
Carpal tunnel syndrome
Carpal tunnel syndrome is a relatively common condition that causes pain, numbness, and tingling in the hand and forearm arm. The condition occurs when the median nerve is compressed as it travels through the carpal tunnel (Figure 3). The carpal tunnel is a narrow passageway on the ventral surface of the wrist. The carpal bones form the floor and sides of the tunnel. The roof of the tunnel is composed of a strong band of connective tissue called the flexor retinaculum (transverse carpal ligament). Because these borders are relatively rigid, the carpal tunnel has little capacity to expand. The nine tendons that flex the fingers and thumb also traverse the carpal tunnel.
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The median nerve provides cutaneous innervation to most of the skin of the thumb, index, middle, and ring fingers. The median nerve also innervates the thenar eminence muscles and the first two lumbricals. Pressure on the median nerve in the carpal tunnel syndrome results when the space within the tunnel decreases in size due to swollen tendon synovial sheaths and/or changes in the osteo-ligamentous elements bordering the tunnel. In most patients, carpal tunnel syndrome becomes progressively worse over time, so early diagnosis and treatment are important. Initially, symptoms can often be relieved with simple measures such as the wearing of a wrist splint or avoiding certain manual activities. If pressure on the median nerve is not relieved, nerve damage and muscle atrophy can result. Some factors that put a patient at increased risk to develop carpal tunnel syndrome are: heredity, repetitive hand use, movements activities that involve extreme flexion or extension of the hand, pregnancy, diabetes, rheumatoid arthritis, and thyroid gland abnormalities.
The initial signs and symptoms include: numbness, tingling, burning, and pain primarily in the thumb and index, middle, and ring fingers, and occasional shock-like feelings in the same digits. Pain or tingling may radiate proximally as far as the shoulder. Subsequently, weakness and clumsiness in the hand will develop so that some activities such as buttoning clothing may be very difficult to perform.
Non-surgical treatments include: bracing or splinting, nonsteroidal anti-inflammatory drugs (NSAIDs), activity changes, nerve gliding exercises, and steroid injections. If nonsurgical treatment does not relieve the symptoms after a period of time, the surgical procedure typically done for carpal tunnel syndrome is called a "carpal tunnel release." This involves cutting the transverse carpal ligament (flexor retinaculum) either via an open or endoscopic procedure. After the ligament is cut there is additional space for expansion within the tunnel and surprisingly this procedure does not cause any noticeable disability. The reason that in our case the patient was initially thought to have carpal tunnel syndrome is that his symptoms were consistent with median nerve compression, and carpal tunnel syndrome is a much more common condition than a thenar glomus tumor. However, this case shows the risk to the clinician of making assumptions. The fact that the median nerve had a normal nerve conduction rate should have clued the original physician to further examine the patient for a cause of his complaint other than carpal tunnel syndrome.
Thenar eminence
“Thenar” refers to the palm of the hand, specifically to the fleshy muscular area at the base of the thumb on the palmar surface of the hand. This area and its muscles are referred to as the thenar eminence. The thenar eminence contains three muscles, the abductor pollicis brevis, flexor pollicis brevis, and the opponens pollicis (Figures 3&4). The bellies of these muscles form a thick, fleshy area on the palmar surface of the hand.
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The recurrent branch of the median nerve innervates all these muscles, but the palmar branch of the median nerve innervates the skin (Figure 5). This latter nerve arises proximal to the flexor retinaculum; thus, the skin of the palm is usually free of symptoms when a patient experiences carpal tunnel syndrome. The thenar eminence is supplied with blood primarily via the princeps pollicis artery, which is a branch of the deep palmar arch. The adductor pollicis muscle is not part of the thenar eminence group, but is an important intrinsic thumb muscle as well (Figure 4B). The adductor pollicis is innervated by the deep branch of the ulnar nerve.
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Specificity vs. sensitivity
A highly sensitive test refers to a clinical test that, if the results are negative, the patient can be assured that they don’t have the disease (low false negative rate). Thus, a test of high sensitivity helps rule out a condition. On the other hand, if a person does not have the disease, how often will a test be negative for that disease in such a patient (true negative rate). That refers to the specificity of a test. In other words, if the test results for a highly specific test is positive you can be nearly certain that they actually have that disease and not some other condition (low false positive rate). A very specific test rules in disease with a high degree of confidence.
Clinical case: Glomus tumor of the hand misdiagnosed as carpal tunnel syndrome: want to learn more about it?
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