Digital Skin Ulceration and Acro-Osteolysis: A Rare Presentation of Severe Carpal Tunnel Syndrome

Dear Editor,

Carpal tunnel syndrome (CTS), an entrapment neuropathy, rarely presents with digital skin ulcers and acro-osteolysis (AO).[1]

A 69-year-old femalenonsmoker presented with a painless skin ulcer on the second left finger for 2 weeks and swelling of the same digit for 6 years duration. She had no symptoms of Raynaud phenomenon and no history of systemic illness, exposure to chemicals, or trauma. There was no family history of AO. Dermatological examination revealed superficial ulceration on the tip of the second distal phalanx of the left hand, Heberden’s nodes, and shortening and swelling of the same digit [Figure 1]. Radial, brachial, and ulnar pulses were normal with cold peripheries. Joint contracture or systemic sclerosis-like skin changes were not detected. The patient did not have any thickened peripheral nerve trunk or tenderness. She had no classic skin lesions of leprosy. The patient’s thermal and touch sensations were normal, yet she had a loss of sensation to pain on the affected finger and surrounding skin. Tinel and Phalen signs were positive. The radiography of the left hand revealed AO of the second left terminal phalanx along with signs of osteoarthritis without calcinosis [Figure 2]. Bone scintigraphy demonstrated degenerative changes without any malignant/metastatic diseases. Histopathological examination revealed findings of wound healing process without evidence of malignancy, sarcoidosis, or leprosy.

Figure 1.

Skin ulceration, shortening, and swelling on the second distal phalanx of the left hand

Figure 2.

Radiography of the left hand revealed acro-osteolysis of the second left terminal phalanx. (a) Anteroposterior view. (b) Oblique view

A blood evaluation revealed a low-titer (<1/320) antinuclear antibody positivity with a nucleolar pattern, negative anti-Sjögren’s-syndrome-related antigen A (SSA), anti-Sjögren’s-syndrome-related antigen B (SSB), anti-Jo1, anti-Scleroderma-70, anti- ribonucleoprotein (RNP), anti-Smith, anti-histone antibodies, rheumatoid factor, and anti-cyclic citrullinated peptide (CCP). Complete blood count, renal and liver function tests, serum glucose and electrolytes, creatine kinase, thyroid-stimulating hormone, erythrocyte sedimentation rate, C-reactive protein, and complete urinalysis were all within normal range. Skin smears were negative for acid-fast bacilli.

Doppler ultrasound scan indicated normal blood flow patterns in axillary, brachial, radial, and ulnar arteries. Electroneuromyography (ENMG) showed a bilateral moderate to severe CTS with bilateral loss of sensory and motor function in the median nerve.

Given the results of work-up, skin ulcers and AO were attributed to underlying CTS after excluding the other well-known causes of AO which are exposure to polyvinyl chloride, repetitive trauma, rheumatic diseases, Raynaud syndrome, leprosy, diabetes mellitus, hyperparathyroidism, sarcoidosis, and genetic disorders.[2] Pure neuritic leprosy (PNL) may also show the same ENMG findings seen in CTS, and positive Tinel and Phalen signs; however, due to the absence of thickened peripheral nerve trunks and tenderness, negative skin smears, and histopathological findings, PNL diagnosis was ruled out. In addition, Turkey is not an endemic region for leprosy, the patient did not have any history of travel to an endemic region or previous residence, or any family history and apparent exposure history to leprosy or hunting.[3]

The skin ulcer improved with topical therapy, yet new digital ulcers were observed on the second and third digits during follow-up visits. The patient was referred to the hand surgery department for surgical decompression.

Skin ulcers and AO due to CTS probably result from compression of the sensory and autonomic fibers of the median nerve in more severe cases.[1] Raynaud phenomenon, color changes of the skin, edema, and swelling of the fingers with subsequent sclerotic skin changes may also be seen due to the impaired vasomotor function.[4] Furthermore, the sensorial deficit can facilitate repetitive physical and thermal microtraumas. The definitive treatment of severe CTS is surgical decompression after which skin ulcers may improve, yet AO is irreversible.[1]

The role of osteoclasts in osteoarthritic bone and cartilage degradation has been shown previously.[5] It has been reported that increased osteoclast formation and higher vascular endothelial growth factor (VEGF) levels may contribute to AO in systemic sclerosis patients representing an association between osteoarthritis and AO.[6] Thus, the coexistence of progressive osteoarthritis may contribute to the occurrence of AO in our patient.

Skin ulceration with AO due to CTS has rarely been reported. Early diagnosis of CTS is vital to prevent irreversible bone damage.

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Conflicts of interest

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