Knuckle pads, also known as heloderma, meaning similar to the skin of the Gila monster lizard for which it is named, are circumscribed, keratotic, fibrous growths over the dorsa of the interphalangeal joints.[1] They are described as well-defined, round, plaque-like, fibrous thickening that may develop at any age, and grow to be 10 to 15mm in diameter in the course of a few weeks or months, then go away over time.[2]
Knuckle pads are sometimes associated with Dupuytren's contracture[3] and camptodactyly,[2]: 595 and histologically, the lesions are fibromas.[2]: 595 [4] Knuckle pads are generally non-responsive to treatment, including corticosteroids, and tend to recur after surgery; however, there has been some effectiveness with intralesional fluorouracil.[5]
Signs and symptoms
Knuckle pads are benign subcutaneous fibrotic nodules that are seen in the finger joints and/or the extensor area of the foot.[6][7][8] From a clinical perspective, these are well-defined, non-compressible, freely moveable lesions that resemble warts and primarily affect the dorsal portion of the proximal interphalangeal (PIP) and, less frequently, the metacarpophalangeal (MCP) joints.[5][9] Knuckle pads are often asymptomatic, painless, and progressive in their growth, reaching their final size of up to 40 mm in diameter. They also do not cause any functional impact on the joints, such as decreased flexibility or altered tendons.[7][5][9]
Causes
Since the pathogenesis is yet unclear, knuckle pads are usually idiopathic.[10] They are a fibromatous illness characterized by fibroblast growth leading to fibrosis.[4]
Knuckle pads can also be acquired subsequent to trauma. In sports like boxers and swimmers, as well as in some occupations like carpet layers, secondary knuckle pads are well-documented.[14][15] Knuckle pads have also been reported in individuals suffering from obsessive-compulsive disorder[16] and bulimia nervosa.[17]
In the lack of targeted and efficacious treatments, a stressful wait-and-see strategy is typically advised.[9] Surgery has also been utilized, though typically without producing a change in appearance. Potential adverse effects include scars, keloids, post-operative loss of joint flexibility, and recurrences.[18][19]
If the insult that caused the acquired knuckle pads is removed, it should heal in a matter of months, similar to what happens in cases of repetitive trauma.[10]
^ abHerold, Manfred; Russe-Wilflingseder, Katharina; Longo, Leonardo (2010). Knuckle Pads—A common problem but good to treat by Laser. AIP Conference Proceedings. pp. 179–183. doi:10.1063/1.3453778.
^ abcdeTamborrini, Giorgio; Gengenbacher, Michael; Bianchi, Stefano (2012-12-30). "Knuckle pads – a rare finding". Journal of Ultrasonography. 12 (51). Medical Communications Sp. z.o.o.: 493–498. doi:10.15557/jou.2012.0037. ISSN2084-8404.
^ abcHasbún, Catalina; Sandoval, Mauricio; Curi, Maximiliano (2019-03-18). "A novel treatment for idiopathic knuckle pads with cantharidin-podophylotoxin-salicylic acid". Pediatric Dermatology. 36 (4). Wiley: 544–545. doi:10.1111/pde.13803. ISSN0736-8046. PMID30883856.
^Kanerva, L. (1998). "Knuckle pads from boxing". European Journal of Dermatology. 8 (5): 359–361. ISSN1167-1122. PMID9683870.
^Calikoğlu, Emel (2003). "Pseudo-knuckle pads: an unusual cutaneous sign of obsessive-compulsive disorder in an adolescent patient". The Turkish Journal of Pediatrics. 45 (4): 348–349. ISSN0041-4301. PMID14768804.
Lu, Yong; Guo, Chenhong; Liu, Qiji; Zhang, Xiyu; Cheng, Lin; Li, Jiangxia; Chen, Bingxi; Gao, Guimin; Zhou, Haibin; Guo, Yishou; Li, Yefu; Gong, Yaoqin (2003-03-21). "A novel mutation of keratin 9 in epidermolytic palmoplantar keratoderma combined with knuckle pads". American Journal of Medical Genetics Part A. 120A (3). Wiley: 345–349. doi:10.1002/ajmg.a.20090. ISSN1552-4825. PMID12838553.
Peterson, Christopher M.; Barnes, Cheryl J.; Davis, Loretta S. (2000). "Knuckle Pads: Does Knuckle Cracking Play an Etiologic Role?". Pediatric Dermatology. 17 (6). Wiley: 450–452. doi:10.1046/j.1525-1470.2000.01819.x. ISSN0736-8046. PMID11123776.
