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.^{[12, 15]}The dermis may occasionally show fibrosis with hypertrophied nerves and scar tissue replacing subcutaneous fat.^[12]

Treatment & Management

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Media Gallery

Hard corn on the lateral surface of fifth toe. Courtesy of James K. DeOrio, MD.
Hard corn over the proximal interphalangeal joint of second toe. Courtesy of James K. DeOrio, MD.
Calluses on the palmar surface of the hands of a body builder. Courtesy of James K. DeOrio, MD.
Screwdriver operator's callus (ie, clavus).

of 4

Table. Clavus Formation Named for Specific Etiology or Location

Table. Clavus Formation Named for Specific Etiology or Location

Vernacular Term	Location	Association
Jeweler's callus, cherry pitter's thumb,^[16]cameo engraver's corn^[17]	Thumb	Digital changes, including callosities related to repetitive use of fine jeweler's instruments, which also may be seen with the use of cherry-pitting tools
Weight lifter's callus^[18]	Callosities over the palmar metacarpophalangeal joints	Caused by the friction of weight-lifting apparatus (This also may be seen in athletes who participate in crew.)
Prayer callus^{[19, 20]}	Callosity on the forehead	From kneeling prayer with the hands on the forehead
Cigarette lighter's thumb^[21]	Hyperkeratosis of the radial aspect of the thumb	Caused by excessive cigarette lighter flicking
Knuckle pads^[22]	Hyperkeratosis over the knuckles	Caused by boxing training
Russell sign^[23]	Callosities of the dorsum of the hand over the metacarpophalangeal and interphalangeal joints	Caused by the friction involved with self-induced emesis in bulimia nervosa
Screwdriver operator's clavus^[24]	Palmar surface of the hand	Occurs at the site of contact with a screwdriver handle
Spine bumps	Hyperkeratosis over the spinal column	Caused by dancing with spinning on one's back
Hairdresser's hand	First finger on dominant hand	Callus formation at the site of friction caused by scissors around the first finger on the dominant hand
Sucking calluses^[25]	Lip, hand, or foot of a newborn	Callus formation at the site of an area of suction on the lip, hand, or foot of a newborn
Vamp disease^[26]	Feet	Clavus formation due to wearing tight high-heeled shoes
Muay Thai kickboxers^[27]	Feet	Callosities on the forefoot (77.5%), on the plantar first metatarsal (55.3%), and on the big toe (33.3%)

Back to List

Author

Nanette B Silverberg, MD Clinical Professor of Dermatology, Icahn School of Medicine at Mount Sinai; Chief of Pediatric Dermatology, Mt Sinai Health Systems, Mount Sinai St Luke's-Roosevelt Hospital and Mt Sinai Beth Israel Medical Centers

Nanette B Silverberg, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Academy of Pediatrics, American Association of University Women, American Medical Association, American Medical Women's Association, Dermatology Foundation, European Society for Pediatric Dermatology, Pediatric Dermatology Research Alliance, Phi Beta Kappa, Sigma Xi, The Scientific Research Honor Society, Society for Pediatric Dermatology, Vitiligo Support International, Women's Dermatologic Society

Disclosure: Received income in an amount equal to or greater than $250 from: Valeant Pharmaceuticals.

Specialty Editor Board

David F Butler, MD Former Section Chief of Dermatology, Central Texas Veterans Healthcare System; Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, Association of Military Dermatologists, Phi Beta Kappa, Texas Dermatological Society

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Additional Contributors

Daniel J Hogan, MD Clinical Professor of Internal Medicine (Dermatology), Nova Southeastern University College of Osteopathic Medicine; Investigator, Hill Top Research, Florida Research Center

Daniel J Hogan, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Contact Dermatitis Society, Canadian Dermatology Association

Disclosure: Nothing to disclose.

Richard K Scher, MD Adjunct Professor of Dermatology, University of North Carolina at Chapel Hill School of Medicine; Professor Emeritus of Dermatology, Columbia University College of Physicians and Surgeons

Richard K Scher, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Physicians, American Medical Association, The Society of Federal Health Professionals (AMSUS), International Society for Dermatologic Surgery, Noah Worcester Dermatological Society, Society for Investigative Dermatology

Disclosure: Nothing to disclose.

Amy Lynn Basile, DO, MPH Sun Coast Hospital/Largo Medical Center

Amy Lynn Basile, DO, MPH is a member of the following medical societies: American Medical Association, American Osteopathic Association, American Osteopathic College of Dermatology

Disclosure: Nothing to disclose.

Acknowledgements

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous authors Ali Hendi, MD; Douglas W. Kress, MD; and Roger Patrick, MD, to the development and writing of this article.

Corns (Clavus) Workup

Histologic Findings

References

Tables

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