Corns (Clavus) Workup

Updated: Jan 10, 2019
  • Author: Nanette B Silverberg, MD; Chief Editor: Dirk M Elston, MD  more...
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Workup

Laboratory Studies

No routine laboratory tests are necessary to evaluate a patient with corns (clavus). [6] Diabetes mellitus, tertiary lues, and other causes of neuropathy should be excluded.

Blood glucose testing is required when paring of a clavus reveals an ulcer or when diabetes mellitus is suspected. In the setting of neuropathy, neuroborreliosis should be considered, and testing is performed with Lyme titers. Rheumatoid factor testing for deformities consistent with rheumatoid arthritis may be indicated. Also see Lyme Disease and Rheumatoid Arthritis.

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Imaging Studies

Imaging studies are required in clavus patients only to detect underlying bony abnormalities. Studies may include radiography and, occasionally, CT scanning of the affected area with bone window settings. [51] Radiographs of the feet in a weight-bearing position are useful for identifying bony prominences and the presence of underlying pathology contributing to foot pain. [34] However, a physical examination may be sufficient to evaluate smaller toe abnormalities. [34]

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Other Tests

Pedobarographic studies are pressure assessments that may be used in clavus patients to detect an altered distribution of foot pressure.

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Procedures

Dermoscopic examination before and after trimming can be helpful with the differential diagnosis of plantar warts, corns, calluses, and healed warts. The translucent central core known as a nucleus may be visualized more easily in a corn using dermoscopy. [49]

Biopsy of the lesions reveals hyperkeratosis and, occasionally, mucin deposition. Paring of the corn can relieve pressure temporarily. Biopsy may be helpful in considering some of the other differential diagnoses, such as warts. Additionally, biopsy can be performed to differentiate clavus from porokeratosis palmoplantaris et disseminatum or discreta. These disorders occur in those aged 20-40 years who have hyperkeratotic plaques on the palms and soles. Biopsy shows a cornoid lamella.

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Histologic Findings

Corns demonstrate epidermal hyperplasia with a thick and compact stratum corneum. Whereas calluses demonstrate only orthokeratosis, parakeratosis may be present in corns, and biopsy specimens demonstrate an endophytic cup shape. The granular cell layer may be decreased or absent. [8, 9] The dermis may occasionally show fibrosis with hypertrophied nerves and scar tissue replacing subcutaneous fat. [8]

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