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CORRESPONDENCE |
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| Year : 2013 | Volume
: 58
| Issue : 2 | Page : 150-151 |
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| Onychoheterotopia: A unique case |
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Kingshuk Chatterjee1, Anita Chaudhuri1, Gautam Chatterjee2
1 Department of Dermatology, Burdwan Medical College and Hospital, Burdwan, West Bengal, India
2 Consultant Surgeon, Khosbagan, Burdwan, India
| Date of Web Publication | 5-Mar-2013 |
Correspondence Address:
Kingshuk Chatterjee
Department of Dermatology, Burdwan Medical College and Hospital, Burdwan, West Bengal
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0019-5154.108064
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How to cite this article:
Chatterjee K, Chaudhuri A, Chatterjee G. Onychoheterotopia: A unique case. Indian J Dermatol 2013;58:150-1 |
Sir,
Onychoheterotopia (syn: Ectopic nail) was first reported by Ohya in 1931. [1] It is defined as growth of nail tissue in any site other than the classical nail unit areas. [2] It is an extremely rare entity with about 55 published cases in the available literature, mostly from Japan, and only few from India. [3]
A 26-year-old male presented to us with a slowly growing, painless, hard projection on the inner left thumb, over the distal phalanx, following a vegetable thorn prick 8 years ago [Figure 1]. There was no sign of spontaneous regression. Neither was it present since birth nor was there any family history of a similar disorder. The patient received no earlier treatment for this disorder. On examination, there was a well-defined, shiny keratotic plaque, 2 × 3 mm in size that morphologically mimicked nail structure, with a depression over the proximal end [Figure 2]. There was no tenderness and the surrounding skin was unremarkable. Radiograph (AP and oblique view) of the left hand revealed neither any bony abnormality of the left thumb distal phalanx nor was there any connection between the abnormal structure and the underlying soft tissue or bone. There was no visible rudimentary or supernumerary structure [Figure 3]. Under ring block anesthesia, using 2% lignocaine without adrenaline, the nail-like structure was completely excised and the gap was closed with interrupted sutures. On histopathological examination, a fully developed nail unit was visualized with the nail matrix and nail bed [Figure 4]. Based on the clinical findings, corroborated with radiologic and histopathologic observations, a diagnosis of acquired onychoheterotopia was made. | Figure 1: Shiny, keratotic, nail - like tissue over the dorsal aspect of the left thumb
Click here to view |
 | Figure 2: Presence of a hard keratotic mass with a proximal depression, resembling nail fold over the dorsomedial aspect of the left thumb
Click here to view |
 | Figure 4: Histopathology showing thick keratinous layer, overlying a squamous epithelium, conforming to nail unit (H and E, ×10)
Click here to view |
The exact pathogenic mechanism of onychoheterotopia still remains obscure. Most of the reported cases are congenital. Various hypotheses have been made to explain this aberration. They include:
- Presence of ectopic germ cells. [3]
- Ectopic nail tissue representing a type of teratoma.
- Dyskeratotic skin growing into a nail. [4]
- Visible portion of the nail plate of an occult polydactyly. [5]
- A component of other inherited syndromes like Pierre-Robin syndrome or Congenital Palmar nail syndrome. [6]
An autosomal-recessive mode of transmission has been suggested but not proved. [7],[8]
The acquired variety develops either after a single overwhelming trauma or after chronic repetitive injuries, which lead to both splitting and implantation of the germinal matrix or heterotopic inoculation of the oncocytes (nail bed cells). Such cases occur predominantly over the dorsal aspect of the hand. [2] Feily, et al. Have reported a case of congenital ectopic nails, where the medial aspects of the index fingers were affected. [9] Osseous defects may occur from the contact of the ectopic matrix with the underlying bone. [7] A keratotic squamous epithelium of mature nail unit, including a corneous nail plate and nail matrix, confirms the diagnosis histopathologically. [2],[10] Our case was unique because the non-dominant hand was involved in the uncommon site of the medial aspect of the distal phalanx of the left thumb after a single minor trauma.
 References | |  |
| 1. | Tomita K, Inoue K, Ichikawa H, Shirai S. Congenital ectopic nails. Plast Reconstr Surg 1997;100:1497-9. 
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| 2. | Riaz F, Rashid RM, Khachemoune A. Onychoheterotopia: Pathogenesis, presentation, and management of ectopic nail. J Am Acad Dermatol 2011;64:161-6.
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| 3. | Narang T, Kanwar AJ. Ectopic nail with polydactyly. J Am Acad Dermatol 2005; 53:1092-3.
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| 4. | Goikoetxea X, Etxebarria I, Careaga M. Posttraumatic ectopic nail: Case report. J Hand Surg Am 2006;31:819-21.
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| 5. | Mahdi S, Beardsmore J. Post-traumatic double fingernail deformity. J Hand Surg Br 1997;22:752-3.
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| 6. | Ena P, Mazzarello V, Dessy LA. Ectopic plantar nail: A report of two cases. Br J Dermatol 2003;149:1071-4.
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| 7. | Rajashekar M, Bhandary S, Shenoy M, Sali AR. Post traumatic ectopic nail. J Postgrad Med 2006;52:218.
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| 8. | Al-Qattan MM, Hassanain J, Hawary MB. Congenital palmar nail syndrome. J Hand Surg Br 1997;22:674-5.
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| 9. | Feily A, Ayoobi A, Yaghoobi R, Kheradmand P. A case of congenital ectopic nails on the bilateral second fingers without bone deformity. Indian J Dermatol Venereol Leprol 2009;75:525-7.
[PUBMED] |
| 10. | Kopera D, Soyer HP, Kerl H. Ectopic calcaneal nail. J Am Acad Dermatol 1996;353:484-5.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4] |
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