You are in: eMedicine Specialties > Dermatology > DISEASES OF THE DERMIS Knuckle PadsArticle Last Updated: Nov 10, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Cheryl J Barnes, MD, Director of Pediatric Dermatology, Associate Professor, Department of Internal Medicine, Division of Dermatology, Medical College of Georgia Cheryl J Barnes is a member of the following medical societies: American Academy of Dermatology Coauthor(s): Loretta Davis, MD, Professor, Department of Internal Medicine, Division of Dermatology, Medical College of Georgia Editors: Gregory J Raugi, MD, PhD, Professor, Department of Internal Medicine, Division of Dermatology, University of Washington at Seattle; Chief, Dermatology Section, Primary and Specialty Care Service, Veterans Administration Medical Center of Seattle; Michael J Wells, MD, Associate Professor, Department of Dermatology, Texas Tech University Health Sciences Center; Edward F Chan, MD, Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania School of Medicine; Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University; William D James, MD, Paul R Gross Professor of Dermatology, University of Pennsylvania School of Medicine; Vice-Chair, Program Director, Department of Dermatology, University of Pennsylvania Health System Author and Editor Disclosure Synonyms and related keywords: halodermia, subcutaneous fibroma, keratosis supracapitularis, discrete keratoderma INTRODUCTIONSection 2 of 10
  BackgroundKnuckle pads are benign, asymptomatic, well-circumscribed, smooth, firm, skin-colored papules, nodules, or plaques, located in the skin over the dorsal aspects of the metacarpophalangeal (MCP) and interphalangeal (IP) joints. A history of repetitive trauma related to sports or occupation is often present. Garrod first described knuckle pads in the medical literature in 1893, but knuckle pads have been observed since the Renaissance era. Allison et al shows a photo of Michelangelo's statue of David displaying knuckle pads (Florence, Italy) as well as his statue of Moses (Rome, Italy), Victory (Florence, Italy), and Giuliano de Medici (Rome, Italy). The name knuckle pad seems to be a misnomer because in most reported cases, lesions occur over the proximal interphalangeal (PIP) joint, not over the knuckles. PathophysiologyKnuckle pads may be idiopathic, genetic, acquired as a response to repetitive trauma, or associated with several other acquired conditions. FrequencyUnited StatesKnuckle pads are a common occurrence. Measurement of prevalence of knuckle pads is difficult because patients are asymptomatic and do not seek medical attention for them. InternationalKnuckle pads were noted in about 9% of subjects in one survey. Patients with Dupuytren contracture are 4 times as likely as the general population to have knuckle pads. Mortality/MorbidityLittle morbidity is associated with knuckle pads. Patients typically are asymptomatic, but some patients experience pain and difficulty with hand functioning, including writing, as a result of their condition. Cosmetic issues drive most patients to seek attention for knuckle pads. RaceNo racial predilection is associated with knuckle pads. SexPrevalence of knuckle pads is equal for men and women. Even in the presence of Dupuytren contracture, the prevalence of knuckle pads remains equal. AgeKnuckle pads can present at any age. They have been reported in young children who bite and suck their fingers. More commonly, knuckle pads are observed in adults older than 40 years. CLINICALSection 3 of 10
HistoryMost patients are asymptomatic. Firm skin-colored papules appear sequentially in multiple sites overlying the MCP and PIP joints of the hands. Individual lesions enlarge into well-defined plaques and nodules. Though complaints of pain or functional impairment of fine motor skills are rare, cosmetic concerns frequently are raised. A history of repetitive trauma often is elicited. PhysicalKnuckle pads are well-circumscribed firm dermal papules, nodules, or plaques approximately 0.5-3 cm in size, located on the extensor aspect of the PIP or MCP joints. If subjected to repetitive injury, knuckle pads may develop over virtually any bony prominence, but the PIP joint area is affected most commonly. CausesMost knuckle pads are idiopathic or are related to repetitive trauma. Work-related trauma with repeated motions or rubbing of the PIP joints or knuckles, as seen in live-chicken hangers in a poultry processing plant, has been reported. Athletes, such as boxers, have been known to traumatize their knuckles and fingers in a repetitive fashion, causing knuckle pads. Surfers have developed "surfer's knots" from repeated friction between the surfboard and the body part exposed to the repeated trauma. A few cases involving the toes have been reported; these cases were thought to be sequelae of ill-fitting shoes. Psychologically disturbed children who bite and suck their fingers cause thickenings that resemble knuckle pads to occur in the skin in the traumatized areas. Patients with bulimia who use their knuckles or fingers to induce emesis sometimes develop fibrotic papules resembling knuckle pads. Some cases of knuckle pads are familial. They have been associated with the autosomal dominant palmoplantar keratoderma with and without ichthyosis vulgaris. Knuckle pads were found in 2 families with autosomal dominant sensorineural deafness and leukonychia (Bart-Pumphrey syndrome). Knuckle pads also have been reported in pseudoxanthoma elasticum. Dupuytren and Peyronie diseases and Ledderhose disease are at times observed together, and the triad may be associated with knuckle pads. Knuckle pads also have been associated with esophageal cancer, hyperkeratosis, and oral leukoplakia. One case report links phenytoin with polyfibromatous syndrome. DIFFERENTIALSSection 4 of 10
Erythema Elevatum Diutinum Granuloma Annulare Xanthomas
| |||||||||||||||||||||||||||||||||||||||||||||||||||||
| Drug Name | Salicylic acid (Dr. Scholl' s) |
|---|---|
| Description | By dissolving the intercellular cement substance, produces desquamation of the horny layer of skin, while not affecting structure of viable epidermis. |
| Adult Dose | Hydrate skin and enhance effects of medication by soaking the affected area in warm water for 5 min prior to use; remove any loose tissue with brush, wash cloth, or emery board and dry thoroughly; improvement should generally occur in 1-2 wk; maximum resolution may be expected after 4-6 wk, although application for up to 12 wk may be necessary |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity; prolonged use in infants, diabetics, and patients with impaired circulation not recommended; use on moles, birthmarks, or warts with hair growing from them, genital or facial warts, or warts on mucous membranes, irritated skin or any area infected or reddened |
| Interactions | None reported |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Avoid contact with mucous membranes, normal skin surrounding warts, and eyes (immediately flush with water for 15 min if contact with eyes or mucous membranes occurs); avoid inhaling vapors |
| Drug Name | Urea (Ureacin, Ureaphil, Carmol) |
|---|---|
| Description | Promotes hydration and removal of excess keratin in conditions of hyperkeratosis. Available in 10-40% concentrations. |
| Adult Dose | Apply prn to affected areas |
| Pediatric Dose | Apply as in adults |
| Contraindications | Documented hypersensitivity; severely impaired renal function, active intracranial bleeding, marked dehydration, frank liver failure; infusion into veins of lower extremities in elderly may cause phlebitis and thrombosis |
| Interactions | May decrease effects of lithium |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Do not use near eyes; caution if applied to broken or swollen skin |
| Media file 1: Knuckle pad over the proximal interphalangeal joint. | |
 | View Full Size Image | Media type: Photo |
| Media file 2: Multiple knuckle pads on various joints of the hand. | |
 | View Full Size Image | Media type: Photo |
Article Last Updated: Nov 10, 2006
