Carpal tunnel syndrome (CTS), the most frequent type of entrapment neuropathy, is caused by compression of the median nerve inside the tunnel formed by the wrist bones and the carpal annular ligament. This condition affects between 1% and 3% of the population, and it is 4 times more common in women than in men. Incidence peaks between the fourth and sixth decade of life, and more than 50% of cases are bilateral. Although most cases are idiopathic, the compression of the nerve is occasionally due to a combination of factors that increase pressure on this nerve. CTS commonly presents with a triad of nocturnal pain, hypoesthesia, and thenar atrophy. We describe a case of CTS that was diagnosed based on the presence of painless cutaneous ulcers with a characteristic location.

An 86-year-old male nonsmoker with a history of cardiac arrhythmias and lower urinary tract symptoms was referred to our unit with painless ulcers on both hands that had appeared 1 month earlier. He was on treatment with furosemide, acenocoumarol, dutasteride, and tamsulosin. During the physical examination, we observed lesions on several fingers of both hands, bullous lesions on the thumbs, and ulcers on the tips of the index and middle fingers of the right hand and middle finger of the left hand. In addition, a short distal phalanx and a short, wide fingernail were observed in the right index finger (Figs. 1 and 2). Radial and brachial peripheral pulses were normal.

Figure 1.

Bilateral ulcers on the fingers located in the median nerve territory. A short right index finger is observed.

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Figure 2.

Detail of ulcers on the tips of the index and middle fingers of the right hand.

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Based on the loss of sensation to pain and the distribution of the lesions, CTS was suspected and the patient was referred to the neurology department. A neurological examination revealed thenar atrophy and loss of pressure sensation in the median nerve territory, with preserved sensation in the forearms and in the ulnar and radial nerve territories of the hands. Electroneurography showed a bilateral loss of sensory and motor function in the median nerve distal to the carpal tunnel.

Blood tests revealed an elevated erythrocyte sedimentation rate and an immunoglobulin A gammopathy, but further testing by the hematology department ruled out multiple myeloma. Rheumatoid factor, cryoglobulin, cold agglutinin, and autoantibody tests were normal.

Hand radiographs showed bone resorption in the distal phalanx of the right index finger (Fig. 3).

Figure 3.

Bone resorption in the distal phalanx of the right index finger.

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The patient was advised to take measures to avoid mechanical and thermal injury, and the skin lesions healed after several weeks with the use of topical treatment. He refused surgical treatment.

Skin ulcers in CTS are rare. They were first described by Bouvier et al.1 in 1979 and few cases have since been published. The ulcerative and disfiguring form of CTS is characterized by the appearance of painless skin ulcers on the fingertips and under the fingernails, sclerodactyly, and acroosteolysis in the sensory hand area innervated by the median nerve.2 Skin involvement is observed in 20% of CTS cases3 and is caused by the compression of autonomic fibers in the median nerve. This explains why skin manifestations occur in patients with severe CTS.4 Vasomotor dysfunction can lead to Raynaud phenomenon and skin necrosis, and sensory dysfunction can result in mechanical or thermal injury, which may in turn cause necrosis to spread.5 Cutaneous lesions include erythema, edema, blisters, painless ulcers on the fingertips and under the fingernails, nail discoloration, onycholysis, gangrene, autoamputation, and acroosteolysis.6 In most patients, the second and third fingers are involved and the main area affected is the volar side of the distal phalanx.7 These fingers are affected most because the innervation of the fingers is mixed, originating from both median and radial nerve fibers, and because they are more vulnerable to injury.8,9 Acral ulcerations and osteolysis are frequently unilateral, although some bilateral cases have been described. In lesions of this type, the differential diagnosis should include collagenopathies, autonomic neuropathies, hematologic diseases, injuries due to external trauma, metabolic diseases, and vascular pathologies.2,10

Diagnosing CTS is simple if the classic manifestations are present; physical examination is therefore useful. Phalen and Hoffman-Tinel signs are highly suggestive of CTS. Imaging techniques are used to evaluate the stricture of the carpal tunnel and rule out the presence of fractures. However, to confirm the diagnosis and evaluate the degree of median nerve involvement, a neurophysiological examination is required.

It is important for the dermatologist to correctly evaluate these types of lesions because early diagnosis is essential to preventing bone lesions and irreversible deformities.