Melanonychia
| Melanonychia | |
|---|---|
| Specialty | Dermatology |
Melanonychia is a black or brown pigmentation of a nail, and may be present as a normal finding on many digits in Afro-Caribbeans, as a result of trauma, systemic disease, or medications, or as a postinflammatory event from such localized events as lichen planus or fixed drug eruption.[1]: 790 [2]: 665
There are two types, longitudinal and transverse melanonychia.[2]: 671
Signs and symptoms
[edit]Melanonychia is defined by a darkening of the nail plate that is brown to black; the pigment in question is typically melanin. It can affect one or more fingernails as well as toenails.[3]
Causes
[edit]Melanocytic activation and melanocyte proliferation are the two primary processes of melanonychia.[3] Increased melanin production from a typical number of activated melanocytes in the nail matrix is referred to as melanocytotic activation. Increased melanin pigment results from a greater quantity of melanocytes within the nail matrix, which is known as melanocyte proliferation.[4]
Both pregnancy and racial melanonychia are physiological causes of longitudinal melanonychia. People with dark skin tones, including African Americans, Asians, Hispanics, and people from the Middle East, often exhibit harmless longitudinal pigmented stripes.[5]
It is important to investigate the possibility of onychotillomania, nail-biting, frictional trauma, and even carpal tunnel syndrome if melanonychia is linked to anomalies of the nail plate or the periungual tissues.[6] A common cause of symmetric melanonychia that affects the great toe, the lateral and external portion of the fourth or fifth toenail, is recurrent trauma from overriding toes or poorly fitting shoes.[5][7]
Skin disorders such onychomycosis, paronychia, psoriasis, lichen planus, amyloidosis, and chronic radiodermatitis can cause inflammation, which can activate melanocytes and result in the formation of a light-brown band. Melanonychia frequently develops after the inflammatory process has resolved.[5] Nonmelanocytic tumors such as subungual linear keratosis,[8] verruca vulgaris, subungual fibrous histiocytoma, basal cell carcinoma, myxoid pseudocyst,[9] Bowen's disease,[10] and onychomatricoma have also been shown to induce melanocytic activation, which leads to longitudinal melanonychia.[11]
Systemic-related melenonychia sometimes presents as numerous bands including the fingernails and toenails. Interestingly, cutaneous and mucosal pigmentation are frequently seen in conjunction with melanonychia linked to nutritional problems, AIDS, and Addison's disease.[12] Alcaptonuria, hemosiderosis, hyperbilirubinemia, and porphyria have all been linked to melanonychia.[5][9]
Medication (particularly chemotherapy drugs), phototherapy, radiation exposure from X-rays, and electron beam therapy are examples of iatrogenic causes of melanocytic activation.[13][14]
Melanonychia linked with syndromes, such as Peutz-Jeghers, Touraine, and Laugier-Hunziker, usually affects numerous digits and is accompanied by mucosal pigmented macules including the lips and oral cavity.[5]
The most frequent cause of brown-black coloration on nails is hematomas. It can be chronic (repeated, tiny trauma) or acute (after a single large trauma).[3]
Both dematiaceous and nondematiaceous fungi can induce fungal melanonychia; the most prevalent ones are Trichophyton rubrum and Scytalidium dimidiatum, followed by Alternaria and Exophiala.[15]
Mechanism
[edit]While melanocytes are found in the nail bed and matrix, most of them are dormant or quiescent.[3] Melanocyte activation in response to trauma, infection, or inflammation starts the manufacture of melanin. Then, melanin-rich melanosomes are transported by dendrites to the developing matrix cells.[16] The nail plate becomes visibly pigmented when these matrix cells migrate in a distal direction and mature into nail plate onychocytes.[5] Melanonychia can also be caused by proliferation of melanocytes in the nail matrix, either with or without the formation of a nest (nevus)[3]
Diagnosis
[edit]It is important to get a complete history, paying close attention to the beginning, development, and potential causes of melanonychia. All twenty nails, skin, and mucous membranes should be examined during the initial physical examination, bearing in mind all possible causes of brown-to-black nail coloration. It is best to rule out the possibility that an exogenous substance on top of or beneath the nail plate is the cause of the linear nail coloring.[17]
Using a dermoscopy can help determine whether a biopsy is required. Because melanonychia is typically difficult to diagnose clinically, a biopsy is usually required to rule out melanoma.[18]
Classification
[edit]Longitudinal melanonychia or melanonychia striata is distinguished by a longitudinal brown-black/grey band that runs from the cuticle or nail matrix proximally to the nail plate's distal free edge. Diffuse or total melanonychia involves the entire nail palate. Transverse melanonychia is characterized by a transverse band across the nail plate's breadth.[3]
Treatment
[edit]The underlying cause of melanonychia determines how to treat it. Regression of pigmentation may be brought on by the management of related systemic or locoregional diseases, the stopping of the offending medication, avoiding trauma, treating infections, or correcting nutritional inadequacies. Benign causes can be monitored and do not require treatment.[3]
Epidemiology
[edit]About half of instances of chromonychia are caused by melanonychia. The most prevalent morphological pattern is longitudinal melanonychia.[19]
See also
[edit]References
[edit]- ^ James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0-7216-2921-0.
- ^ a b Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.
- ^ a b c d e f g Singal, Archana; Bisherwal, Kavita (2020). "Melanonychia: Etiology, Diagnosis, and Treatment". Indian Dermatology Online Journal. 11 (1). Medknow: 1–11. doi:10.4103/idoj.idoj_167_19. ISSN 2229-5178. PMC 7001389. PMID 32055501.
- ^ Tosti, Antonella; Baran, Robert; Piraccini, Bianca Maria; Cameli, Norma; Fanti, Pier Alessandro (1996). "Nail matrix nevi: A clinical and histopathologic study of twenty-two patients". Journal of the American Academy of Dermatology. 34 (5). Elsevier BV: 765–771. doi:10.1016/s0190-9622(96)90010-9. ISSN 0190-9622.
- ^ a b c d e f André, Josette; Lateur, Nadine (2006). "Pigmented Nail Disorders". Dermatologic Clinics. 24 (3). Elsevier BV: 329–339. doi:10.1016/j.det.2006.03.012. ISSN 0733-8635.
- ^ Aratari, Ester (1984-04-01). "Carpal Tunnel Syndrome Appearing With Prominent Skin Symptoms". Archives of Dermatology. 120 (4): 517. doi:10.1001/archderm.1984.01650400099023. ISSN 0003-987X. PMID 6703757.
- ^ Baran, Robert (1987). "Frictional Longitudinal Melanonychia: A New Entity". Dermatology. 174 (6). S. Karger AG: 280–284. doi:10.1159/000249199. ISSN 1018-8665. PMID 3622879.
- ^ Baran; Perrin (1999). "Linear melanonychia due to subungual keratosis of the nail bed: a report of two cases". British Journal of Dermatology. 140 (4). Oxford University Press (OUP): 730–733. doi:10.1046/j.1365-2133.1999.02780.x. ISSN 0007-0963.
- ^ a b Baran, Robert; Kechijian, Paul (1989). "Longitudinal melanonychia (melanonychia striata): Diagnosis and management". Journal of the American Academy of Dermatology. 21 (6). Elsevier BV: 1165–1175. doi:10.1016/s0190-9622(89)70324-8. ISSN 0190-9622. PMID 2685057.
- ^ Sass, U.; André, J.; Stene, J.-J.; Noel, J.-Ch. (1998). "Longitudinal melanonychia revealing an intraepidermal carcinoma of the nail apparatus: Detection of integrated HPV-16 DNA". Journal of the American Academy of Dermatology. 39 (3). Elsevier BV: 490–493. doi:10.1016/s0190-9622(98)70331-7. ISSN 0190-9622. PMID 9738788.
- ^ Fayol, R. Baran, C. Perrin, F. Labr, J. (2000-10-01). "Onychomatricoma with Misleading Features". Acta Dermato-Venereologica. 80 (5). Medical Journals Sweden AB: 370–372. doi:10.1080/000155500459330. ISSN 0001-5555. PMID 11200837.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Cribier, Bernard; Mena, Marcello Leiva; Rey, David; Partisani, Maria; Fabien, Vincent; Lang, Jean-Marie; Grosshans, Edouard (1998-10-01). "Nail Changes in Patients Infected With Human Immunodeficiency Virus". Archives of Dermatology. 134 (10). American Medical Association (AMA). doi:10.1001/archderm.134.10.1216. ISSN 0003-987X.
- ^ O'Branski, Erin E.; Ware, Russell E.; Prose, Neil S.; Kinney, Thomas R. (2001). "Skin and nail changes in children with sickle cell anemia receiving hydroxyurea therapy". Journal of the American Academy of Dermatology. 44 (5). Elsevier BV: 859–861. doi:10.1067/mjd.2001.113471. ISSN 0190-9622. PMID 11312437.
- ^ Quinlan, Kathryn E.; Janiga, Jennifer J.; Baran, Robert; Lim, Henry W. (2005). "Transverse melanonychia secondary to total skin electron beam therapy: A report of 3 cases". Journal of the American Academy of Dermatology. 53 (2). Elsevier BV: S112 – S114. doi:10.1016/j.jaad.2004.11.020. ISSN 0190-9622.
- ^ Finch, Justin; Arenas, Roberto; Baran, Robert (2012). "Fungal melanonychia". Journal of the American Academy of Dermatology. 66 (5). Elsevier BV: 830–841. doi:10.1016/j.jaad.2010.11.018. ISSN 0190-9622.
- ^ Perrin, Ch.; Michiels, J. F.; Pisani, A.; Ortonne, J. P. (1997). "Anatomic Distribution of Melanocytes in Normal Nail Unit". The American Journal of Dermatopathology. 19 (5). Ovid Technologies (Wolters Kluwer Health): 462–467. doi:10.1097/00000372-199710000-00005. ISSN 0193-1091.
- ^ Jefferson, Julie; Rich, Phoebe (2012). "Melanonychia". Dermatology Research and Practice. 2012. Hindawi Limited: 1–8. doi:10.1155/2012/952186. ISSN 1687-6105. PMC 3390039. PMID 22792094.
- ^ Jellinek, Nathaniel (2007). "Nail matrix biopsy of longitudinal melanonychia: Diagnostic algorithm including the matrix shave biopsy". Journal of the American Academy of Dermatology. 56 (5). Elsevier BV: 803–810. doi:10.1016/j.jaad.2006.12.001. ISSN 0190-9622.
- ^ Bae, S; Lee, M; Lee, J (2018). "Distinct Patterns and Aetiology of Chromonychia". Acta Dermato Venereologica. 98 (1). Medical Journals Sweden AB: 108–113. doi:10.2340/00015555-2798. ISSN 0001-5555.
Further reading
[edit]- Jin, Hyunju; Kim, Jeong-Min; Kim, Gun-Wook; Song, Margaret; Kim, Hoon-Soo; Ko, Hyun-Chang; Kim, Byung-Soo; Kim, Moon-Bum (2016). "Diagnostic criteria for and clinical review of melanonychia in Korean patients". Journal of the American Academy of Dermatology. 74 (6). Elsevier BV: 1121–1127. doi:10.1016/j.jaad.2015.12.039. ISSN 0190-9622. PMID 26830866.
- Tosti, Antonella; Piraccini, Bianca Maria; de Farias, Débora Cadore (2009). "Dealing with Melanonychia". Seminars in Cutaneous Medicine and Surgery. 28 (1). Frontline Medical Communications, Inc.: 49–54. doi:10.1016/j.sder.2008.12.004. ISSN 1085-5629. PMID 19341943.