- Email: [email protected]
Retronychia: Proximal ingrowing of the nail plate
Retronychia: Proximal ingrowing of the nail plate David A. de Berker, MRCP,a Bertrand Richert, MD, PhD,b Edith Duhard, MD,c Bianca Maria Piraccini, MD, PhD,d Josette Andre´, MD,e and Robert Baran, MDf Bristol, United Kingdom; Lie`ge, Belgium; Tours and Cannes, France; and Bologna, Italy Background: Proximal nail fold inflammation can be caused by many diseases and has not previously been recognized as a result of posterior embedding of the nail. We describe a new pattern of ingrowth that we have termed retronychia (‘‘retro’’—Latin for backwards; ‘‘onychia’’—Greek for nail). The term describes a combination of proximal nail plate ingrowth into the proximal nail fold which is associated with multiple generations of nail plate misaligned beneath the proximal nail. Objective: To describe a new pattern of nail ingrowth which causes a specific form of proximal nail fold paronychia. Methods: Collective cases were reported to a European Nail Society expert group. Results: Persistent proximal nail fold inflammation can result from an episode of trauma that disturbs longitudinal nail growth and results in reverse embedding of the nail plate. This can cause pain, inflammation, and granulation tissue formation, and is typically relieved by avulsion and antiinflammatory treatment. Limitations: We cannot demonstrate causality between the proposed precipitants and the clinical features. Conclusion: Retroncyhia represents proximal ingrowth of the nail that occurs when the nail embeds backwards into the proximal nail fold. Nail plate avulsion with supplementary medical management is curative. ( J Am Acad Dermatol 2008;58:978-83.)
he lateral ingrowth of nails is well described.1 Distal ingrowth into the nail bed is largely a temporary disease of infants or related to regrowth of a nail after it is shed or surgically removed. It may also occur via longitudinal
T
From the Bristol Dermatology Centre,a Bristol Royal Infirmary; the Dermatology Department,b University of Lie`ge, Belgium; Service de Dermatologie,c Centre Hospitalier Re´gional Universitaire, Tours; Department of Dermatology,d University of Bologna; Department of Dermatology,e Centre Hospitalier Universitaire St-Pierre, Universite´ Libre de Bruxelles, Lie`ge, Belgium; and the Nail Disease Centre,f Cannes, France. Funding sources: None. Conflicts of interest: None declared. Presented at the European Nail Society meeting of the 16th Annual Meeting of the European Academy of Dermatology and Venereology, Vienna, Austria, May 16-20, 2007. Reprints not available from the authors. Correspondence to: David de Berker, MRCP, Bristol Dermatology Centre, Bristol Royal Infirmary, Bristol, BS2 8HW, United Kingdom. E-mail: [email protected]. Published online March 31, 2008. 0190-9622/$34.00 ª 2008 by the American Academy of Dermatology, Inc. doi:10.1016/j.jaad.2008.01.013
978
overcurvature, where nails are not cut and the free edge embeds into the digital pulp.2 Other than in abstract form,3 proximal ingrowth has not been previously reported. We present a series of 19 cases described in meetings of the European Nail Society. The entity has emerged as a collective observation of leading nail expert members of the society and adds to our understanding of the concept of onychomadesis and paronychia of the proximal nail fold.
METHODS All cases were contributed and discussed by members of the European Nail Society expert group over a period of 8 yean 8-year period. Patients were managed in five different dermatology units, representing centers of nail disease management in Europe. Patients were followed for sufficient time to document complete nail regrowth. Each case was documented photographically, ensuring corroboration within the authorship.
RESULTS Three illustrative case histories are given in detail below.
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Fig 1. Case 1. A, Both great toes are affected by retronychia. B, The nail is thickened, yellow, and higher proximally than distally. Proximal ingrowth can be seen with swelling most prominent at the interaction of the lateral horns and proximal nail fold (A and B). The nail can be avulsed using a proximal approach (C). Both the old and new nails can be seen (arrows). A third layer of nail remains attached (D) with a residual point of ingrowth. E, Twelve months later, all features are resolved.
Case 1 A 69-year-old female with a 6-month history of discharge from the proximal nail fold of both big toes (Fig 1) presented to one of the participating centers. Repeated courses of antibiotics provided no therapeutic benefit. She had suffered thrombophlebitis during the last year, but no other skin disease was noted. She was taking lofepramine, chlordiazepoxide, and amiodarone. There was no history of a traumatic precipitating event. Both great toenails were thickened, profoundly yellow, and elevated at the proximal margin more than distally. Avulsion of the two nails under local anesthetic revealed three layers of nail tiered from the matrix to the dorsal surface of the nail. With routine wound care, normal nails regrew within 12 months. Case 2 A 71-year-old male fell on his outstretched hands 10 weeks before presenting with pain and inflammation of the index finger and thumb on his right
and left hands, respectively (Fig 2). Management was achieved with analgesics and antibiotics, although infection was not a clear feature. The nail plate progressed to push through the proximal nail fold before being shed 6 months later. There was residual scarring of periungual tissues. Subsequent nail growth was normal. Case 3 A 69-year-old female presented with a 6-month history of pain, recurrent ‘‘infection,’’ and discharge from beneath the proximal nail fold of both big toenails (Fig 3). She was an active person whose exercise became limited by pain from her nails. The primary care physician had provided two courses of broad spectrum antibiotics without resolution. Treatment was surgical nail avulsion under local anesthetic, revealing three layers of proximal nail lying tiered from the matrix to the dorsal surface of the nail. Routine wound care resulted in resolution of the proximal nail fold pathology and return of normal toenails.
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Fig 2. Case 2. Trauma from falling on outstretched hands resulted in the nail being pushed obliquely backwards to embed in the proximal nail fold (A) before pushing its way through entirely (B) and being shed with residual nail fold scarring (C).
SUMMARY Nineteen cases are presented in summary (Table I). The mean age was 39 years (range, 14-71 yrs), with a preponderance of women (16/19 patients [84%]). All patients presented with the cardinal features of inflammation of the proximal
Fig 3. Following proximal nail fold embedding (A), the nail plate is avulsed, demonstrating multiple layers of proximal nail (B) and a subsequent return to normal nail growth (C).
nail fold (proximal paronychia) and elevation of the proximal nail plate beneath the nail fold such that it was higher than the distal edge. In most patients, the nail plate was thickened and more yellow than normal. Granulation tissue was common (6/19 patients [32%]) at the most prominent point of
Age (y)
Sex
Digit toes
Digit fingers
Duration (mo.)
Precipitating event
Treatment
Outcome
Comments
1 2 3 4
54 71 69 14
F M F F
R1 1 L1 — R1 1 L1 L1
— R2 1 L1 — —
8 6 6 8
Thrombophlebitis Fall with trauma to hands None Running; kept nail long
Resolution Resolution Resolution Resolution
— — — New nail slightly thicker than normal
5 6 7 8 9
68 48 62 35 44
F M F M F
— R1 — R1 R1
R1 — L1 — —
6 5 3 6 10
Resolution Resolution Resolution Resolution Resolution
Beau’s lines — — — —
10
20
F
R1 1 L1
—
2
Hiking
Resolution
—
11 12 13 14 15
20 41 18 67 43
F F F F F
L1 L1 R1 L1 R1
— — — — —
4 3 4 5 3
None None None Hiking with poor footwear Hiking
Avulsion 1 antibiotics None Avulsion 1 antibiotics Curettage 1 CO2 laser of nail fold granulation tissue; avulsion 1 injected and topical corticosteroids Avulsion 1 antibiotics Avulsion Avulsion Avulsion Avulsion 1 CO2 laser 1 topical corticosteroids Avulsion 1 CO2 laser 1 topical corticosteroids Avulsion 1 topical corticosteroids Avulsion Avulsion Avulsion Avulsion
Resolution Resolution Resolution Resolution Resolution
16
13
F
R1
—
4
Poor footwear
Avulsion
Resolution
17
27
F
R1
—
24
High heels
Avulsion
Resolution
18
19
F
L1
—
6
None
Avulsion
Resolution
19
16
F
R1
—
[3
None
Avulsion
Resolution
Arthritis Trauma Paronychia Jogging None
J AM ACAD DERMATOL
Case no.
VOLUME 58, NUMBER 6
Table I. Detail of 19 cases of retronychia
— — — — Raynaud’s, granulation tissue at nail fold Granulation tissue at nail fold Scleroderma and onychomycosis Granulation tissue at nail fold Anorexia nervosa with Beau’s lines on several nails
de Berker et al 981
982 de Berker et al
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Fig 4. The evolution and features of retronychia.
ingrowing. This was typically at the proximal lateral horn of the nail at the junction of the proximal and lateral nail folds (Figs 1, B and 3, A). Toes were affected in 16 of 19 (84%) subjects, where it was always limited to the big toe, bilaterally in 3 of 19 (16%) instances. The hand was affected in 3 of 19 (16%) cases, with the thumb and index finger affected in case 2 and the thumb alone in cases 5 and 7. Inflammation was universal, pain was variable, and purulent discharge with frank infection was uncommon. Most patients (11/19 [58%]) gave a history of a precipitating event. In most cases, it was an episode of trauma; in a minority, it was a systemic illness, giving rise to Beau’s lines. Where trauma was contributory, it was typically from footwear. All were managed with routine wound care following avulsion. Oral antibiotics were used in cases presenting with discharge, pain, or extensive inflammation. Otherwise, local antiseptic ointments and soaks at dressing changes were sufficient for treatment. Curettage (1/19 [5%]) and laser ablation (3/19 [16%]) of granulation tissue was undertaken but was unsuccessful until the avulsion and removal of the ingrown layers of nail. Resolution of inflammatory changes was seen in all cases with avulsion as the definitive procedure. When the proximal margin of the uppermost nail plate was visible at the proximal nail fold, the technique of proximal avulsion was suitable.4 This entails approaching the nail with an elevator or needle holder from the proximal aspect, in contrast to the traditional method of avulsion by lifting the nail from the distal margin. Avulsion of the deepest layer of nail in continuity
with the matrix was not required. In all cases, findings at surgery were the same, with between two and four new nail plates superimposed on each other, creating a multilayer sandwich of proximal nail beneath the nail fold. The oldest, uppermost nail was embedded into the ventral aspect of the proximal nail fold (Fig 4), giving rise to the pain, inflammation, and varying degrees of granulation tissue reaction. The authors observed that the uppermost nail was more adherent to the nail bed and resistant to avulsion than normally encountered. Pain and inflammation subsided rapidly after avulsion followed by normal nail regrowth.
DISCUSSION This series describes a disease termed retronychia, where the nail plate loses continuity with the matrix. In normal circumstances, such as in a Beau’s line, onychomadesis, or crush injury, the original nail would remain aligned in the horizontal axis so that the new, forming nail is able to push the separated original nail out distally. The proximal nail fold plays a part in maintaining this alignment by preventing the old nail from rising up in response to pressure from behind. In retronychia, something disrupts the alignment. The most common scenario is distal trauma from footwear that pushes the nail back and upwards, so that the proximal margin is above the leading edge of the newly forming nail (Fig 4). As this new nail grows forward, it fails to push the old nail plate distally, but passes beneath it and pushes the old nail further upwards. This happens to a minor degree in uncomplicated nail regrowth after trauma,
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where the early stages of new nail growth can be seen beneath the shed nail. However, in retronychia, multiple layers of nail direct the proximal margin of the old nail into the ventral aspect of the proximal nail fold, creating a proximally ingrowing nail. As the proximal nail fold rises and becomes inflamed, footwear presses downwards, exacerbating the trauma between nail fold and nail plate. These features also contribute to the yellow color of the nail, which appears multifactorial. Firstly, the nail is thickened so that it becomes laminated with a further element of nail beneath it. Secondly, there is often an element of onycholysis, and thirdly, there is significant inflammatory exudate which accumulates beneath the nail. Granulation tissue is common; however, treatment of this finding alone did not normalize the nail. In this sense, it is analogous to the exuberant granulation tissue seen in lateral ingrowth.5 None of the patients in our series were taking medication, such as retinoids,6 cyclosporin,7 protease inhibitors,8 or antieepidermal growth factor receptor agents9 that at times are associated with nail fold granulation tissue. For most cases affecting the big toes, it is likely that the precipitating event is a force against the free edge, pushing the nail backwards. Force could be a single episode, or repetitive, as in jogging with cases 4 and 8 or hiking in cases 10, 14, and 15. Poorly fitting or tight-toed footwear, such as high heels, can also be a factor, as seen in cases 16 and 17. In case 2, falling and knocking the nails in the thumb and finger precipitated a similar process. Case 5 illustrates that it is possible for the problem to be initiated by a combination of local distortion associated with arthritis and a systemic event that gives rise to a Beau’s line, representing the break between an old and new nail. In an effort to correlate the experience of surgical avulsion with the pathogenesis, and explain why these nails are not just shed typically following trauma or in instances of onychomadesis, we noted that the uppermost nail appeared to have unusually firm attachment to the nail bed and nail folds. In some cases, this attachment was between the nail plate and distal nail bed; in others, the attachment was between the lateral horns of the nail plate and the sulcus of the nail fold. It may be that where such adherence is stronger, the normal shedding process progresses
abnormally. Alternatively, there could be a baseline defect in the proximal nail fold; if it normally acts as a restricting band holding down the proximal nail plate, where it is diseased the nail can be forced upwards and be predisposed to retronychia.
CONCLUSION We conclude that retronychia (‘‘retro’’—Latin for backwards; ‘‘onychia’’—Greek for nail) is a useful term describing a combination of proximal nail plate ingrowth into the proximal nail fold that is associated with multiple generations of nail plate misalignment beneath the proximal nail and is usually precipitated by trauma. There is a sizeable literature demonstrating that avulsion alone is not useful as treatment of lateral ingrowing nail.10 By contrast, retronychia is a nonrecurrent pathology and, once treated with avulsion, it resolves without complications or relapse. Referrals were kindly provided by Drs L. De Raeve, from the Vrije Universiteit Brussel, Belgium, and by J. Rendall, from Hereford County Hospital, United Kingdom.
REFERENCES 1. Bos AM, van Tilburg MW, van Sorge AA, Klinkenbijl JH. Randomized clinical trial of surgical technique and local antibiotics for ingrowing toenail. Br J Surg 2007;94:292-6. 2. Baran R, Haneke E. Matricectomy and nail ablation. Hand Clin 2002;18:693-6. 3. de Berker DAR, Rendall JRS. Retronychia—Proximal ingrowing nail. J Eur Acad Dermatol Venereol 1999;12(suppl 2):S126. 4. Scher RK. Surgical avulsion of nail plates by a proximal to distal technique. J Dermatol Surg Oncol 1981;7:296-7. 5. Zook EG, Baran R, Haneke E, Dawber RPR. Nail surgery and traumatic abnormalities. In: Baran R, Dawber RPR, de Berker DAR, Haneke E, Tosti A, eds. Nail diseases and their management (3rd ed). London: Blackwell Science, 2001. pp. 425-514. 6. Campbell JP, Grekin RC, Ellis CN, Matsuda-John SS, Swanson NA, Voorhees JJ. Retinoid therapy is associated with excess granulation tissue responses. J Am Acad Dermatol 1983;9: 708-13. 7. Higgins EM, Hughes JR, Snowden S, Pembroke AC. Cyclosporin-induced periungual granulation tissue. Br J Dermatol 1995;132:829-30. 8. Bouscarat F, Bouchard C, Bouhour D. Paronychia and pyogenic granuloma of the great toes in patients treated with indinavir. N Engl J Med 1998;338:1776-7. 9. Hu JC, Sadeghi P, Pinter-Brown LC, Yashar S, Chiu MW. Cutaneous side effects of epidermal growth factor receptor inhibitors: Clinical presentation, pathogenesis, and management. J Am Acad Dermatol 2007;56:317-26. 10. Rounding C, Bloomfield S. Surgical treatments for ingrowing toenails. Cochrane Database Syst Rev 2005;18: CD001541.
he lateral ingrowth of nails is well described.1 Distal ingrowth into the nail bed is largely a temporary disease of infants or related to regrowth of a nail after it is shed or surgically removed. It may also occur via longitudinal
T
From the Bristol Dermatology Centre,a Bristol Royal Infirmary; the Dermatology Department,b University of Lie`ge, Belgium; Service de Dermatologie,c Centre Hospitalier Re´gional Universitaire, Tours; Department of Dermatology,d University of Bologna; Department of Dermatology,e Centre Hospitalier Universitaire St-Pierre, Universite´ Libre de Bruxelles, Lie`ge, Belgium; and the Nail Disease Centre,f Cannes, France. Funding sources: None. Conflicts of interest: None declared. Presented at the European Nail Society meeting of the 16th Annual Meeting of the European Academy of Dermatology and Venereology, Vienna, Austria, May 16-20, 2007. Reprints not available from the authors. Correspondence to: David de Berker, MRCP, Bristol Dermatology Centre, Bristol Royal Infirmary, Bristol, BS2 8HW, United Kingdom. E-mail: [email protected]. Published online March 31, 2008. 0190-9622/$34.00 ª 2008 by the American Academy of Dermatology, Inc. doi:10.1016/j.jaad.2008.01.013
978
overcurvature, where nails are not cut and the free edge embeds into the digital pulp.2 Other than in abstract form,3 proximal ingrowth has not been previously reported. We present a series of 19 cases described in meetings of the European Nail Society. The entity has emerged as a collective observation of leading nail expert members of the society and adds to our understanding of the concept of onychomadesis and paronychia of the proximal nail fold.
METHODS All cases were contributed and discussed by members of the European Nail Society expert group over a period of 8 yean 8-year period. Patients were managed in five different dermatology units, representing centers of nail disease management in Europe. Patients were followed for sufficient time to document complete nail regrowth. Each case was documented photographically, ensuring corroboration within the authorship.
RESULTS Three illustrative case histories are given in detail below.
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Fig 1. Case 1. A, Both great toes are affected by retronychia. B, The nail is thickened, yellow, and higher proximally than distally. Proximal ingrowth can be seen with swelling most prominent at the interaction of the lateral horns and proximal nail fold (A and B). The nail can be avulsed using a proximal approach (C). Both the old and new nails can be seen (arrows). A third layer of nail remains attached (D) with a residual point of ingrowth. E, Twelve months later, all features are resolved.
Case 1 A 69-year-old female with a 6-month history of discharge from the proximal nail fold of both big toes (Fig 1) presented to one of the participating centers. Repeated courses of antibiotics provided no therapeutic benefit. She had suffered thrombophlebitis during the last year, but no other skin disease was noted. She was taking lofepramine, chlordiazepoxide, and amiodarone. There was no history of a traumatic precipitating event. Both great toenails were thickened, profoundly yellow, and elevated at the proximal margin more than distally. Avulsion of the two nails under local anesthetic revealed three layers of nail tiered from the matrix to the dorsal surface of the nail. With routine wound care, normal nails regrew within 12 months. Case 2 A 71-year-old male fell on his outstretched hands 10 weeks before presenting with pain and inflammation of the index finger and thumb on his right
and left hands, respectively (Fig 2). Management was achieved with analgesics and antibiotics, although infection was not a clear feature. The nail plate progressed to push through the proximal nail fold before being shed 6 months later. There was residual scarring of periungual tissues. Subsequent nail growth was normal. Case 3 A 69-year-old female presented with a 6-month history of pain, recurrent ‘‘infection,’’ and discharge from beneath the proximal nail fold of both big toenails (Fig 3). She was an active person whose exercise became limited by pain from her nails. The primary care physician had provided two courses of broad spectrum antibiotics without resolution. Treatment was surgical nail avulsion under local anesthetic, revealing three layers of proximal nail lying tiered from the matrix to the dorsal surface of the nail. Routine wound care resulted in resolution of the proximal nail fold pathology and return of normal toenails.
980 de Berker et al
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Fig 2. Case 2. Trauma from falling on outstretched hands resulted in the nail being pushed obliquely backwards to embed in the proximal nail fold (A) before pushing its way through entirely (B) and being shed with residual nail fold scarring (C).
SUMMARY Nineteen cases are presented in summary (Table I). The mean age was 39 years (range, 14-71 yrs), with a preponderance of women (16/19 patients [84%]). All patients presented with the cardinal features of inflammation of the proximal
Fig 3. Following proximal nail fold embedding (A), the nail plate is avulsed, demonstrating multiple layers of proximal nail (B) and a subsequent return to normal nail growth (C).
nail fold (proximal paronychia) and elevation of the proximal nail plate beneath the nail fold such that it was higher than the distal edge. In most patients, the nail plate was thickened and more yellow than normal. Granulation tissue was common (6/19 patients [32%]) at the most prominent point of
Age (y)
Sex
Digit toes
Digit fingers
Duration (mo.)
Precipitating event
Treatment
Outcome
Comments
1 2 3 4
54 71 69 14
F M F F
R1 1 L1 — R1 1 L1 L1
— R2 1 L1 — —
8 6 6 8
Thrombophlebitis Fall with trauma to hands None Running; kept nail long
Resolution Resolution Resolution Resolution
— — — New nail slightly thicker than normal
5 6 7 8 9
68 48 62 35 44
F M F M F
— R1 — R1 R1
R1 — L1 — —
6 5 3 6 10
Resolution Resolution Resolution Resolution Resolution
Beau’s lines — — — —
10
20
F
R1 1 L1
—
2
Hiking
Resolution
—
11 12 13 14 15
20 41 18 67 43
F F F F F
L1 L1 R1 L1 R1
— — — — —
4 3 4 5 3
None None None Hiking with poor footwear Hiking
Avulsion 1 antibiotics None Avulsion 1 antibiotics Curettage 1 CO2 laser of nail fold granulation tissue; avulsion 1 injected and topical corticosteroids Avulsion 1 antibiotics Avulsion Avulsion Avulsion Avulsion 1 CO2 laser 1 topical corticosteroids Avulsion 1 CO2 laser 1 topical corticosteroids Avulsion 1 topical corticosteroids Avulsion Avulsion Avulsion Avulsion
Resolution Resolution Resolution Resolution Resolution
16
13
F
R1
—
4
Poor footwear
Avulsion
Resolution
17
27
F
R1
—
24
High heels
Avulsion
Resolution
18
19
F
L1
—
6
None
Avulsion
Resolution
19
16
F
R1
—
[3
None
Avulsion
Resolution
Arthritis Trauma Paronychia Jogging None
J AM ACAD DERMATOL
Case no.
VOLUME 58, NUMBER 6
Table I. Detail of 19 cases of retronychia
— — — — Raynaud’s, granulation tissue at nail fold Granulation tissue at nail fold Scleroderma and onychomycosis Granulation tissue at nail fold Anorexia nervosa with Beau’s lines on several nails
de Berker et al 981
982 de Berker et al
J AM ACAD DERMATOL JUNE 2008
Fig 4. The evolution and features of retronychia.
ingrowing. This was typically at the proximal lateral horn of the nail at the junction of the proximal and lateral nail folds (Figs 1, B and 3, A). Toes were affected in 16 of 19 (84%) subjects, where it was always limited to the big toe, bilaterally in 3 of 19 (16%) instances. The hand was affected in 3 of 19 (16%) cases, with the thumb and index finger affected in case 2 and the thumb alone in cases 5 and 7. Inflammation was universal, pain was variable, and purulent discharge with frank infection was uncommon. Most patients (11/19 [58%]) gave a history of a precipitating event. In most cases, it was an episode of trauma; in a minority, it was a systemic illness, giving rise to Beau’s lines. Where trauma was contributory, it was typically from footwear. All were managed with routine wound care following avulsion. Oral antibiotics were used in cases presenting with discharge, pain, or extensive inflammation. Otherwise, local antiseptic ointments and soaks at dressing changes were sufficient for treatment. Curettage (1/19 [5%]) and laser ablation (3/19 [16%]) of granulation tissue was undertaken but was unsuccessful until the avulsion and removal of the ingrown layers of nail. Resolution of inflammatory changes was seen in all cases with avulsion as the definitive procedure. When the proximal margin of the uppermost nail plate was visible at the proximal nail fold, the technique of proximal avulsion was suitable.4 This entails approaching the nail with an elevator or needle holder from the proximal aspect, in contrast to the traditional method of avulsion by lifting the nail from the distal margin. Avulsion of the deepest layer of nail in continuity
with the matrix was not required. In all cases, findings at surgery were the same, with between two and four new nail plates superimposed on each other, creating a multilayer sandwich of proximal nail beneath the nail fold. The oldest, uppermost nail was embedded into the ventral aspect of the proximal nail fold (Fig 4), giving rise to the pain, inflammation, and varying degrees of granulation tissue reaction. The authors observed that the uppermost nail was more adherent to the nail bed and resistant to avulsion than normally encountered. Pain and inflammation subsided rapidly after avulsion followed by normal nail regrowth.
DISCUSSION This series describes a disease termed retronychia, where the nail plate loses continuity with the matrix. In normal circumstances, such as in a Beau’s line, onychomadesis, or crush injury, the original nail would remain aligned in the horizontal axis so that the new, forming nail is able to push the separated original nail out distally. The proximal nail fold plays a part in maintaining this alignment by preventing the old nail from rising up in response to pressure from behind. In retronychia, something disrupts the alignment. The most common scenario is distal trauma from footwear that pushes the nail back and upwards, so that the proximal margin is above the leading edge of the newly forming nail (Fig 4). As this new nail grows forward, it fails to push the old nail plate distally, but passes beneath it and pushes the old nail further upwards. This happens to a minor degree in uncomplicated nail regrowth after trauma,
de Berker et al 983
J AM ACAD DERMATOL VOLUME 58, NUMBER 6
where the early stages of new nail growth can be seen beneath the shed nail. However, in retronychia, multiple layers of nail direct the proximal margin of the old nail into the ventral aspect of the proximal nail fold, creating a proximally ingrowing nail. As the proximal nail fold rises and becomes inflamed, footwear presses downwards, exacerbating the trauma between nail fold and nail plate. These features also contribute to the yellow color of the nail, which appears multifactorial. Firstly, the nail is thickened so that it becomes laminated with a further element of nail beneath it. Secondly, there is often an element of onycholysis, and thirdly, there is significant inflammatory exudate which accumulates beneath the nail. Granulation tissue is common; however, treatment of this finding alone did not normalize the nail. In this sense, it is analogous to the exuberant granulation tissue seen in lateral ingrowth.5 None of the patients in our series were taking medication, such as retinoids,6 cyclosporin,7 protease inhibitors,8 or antieepidermal growth factor receptor agents9 that at times are associated with nail fold granulation tissue. For most cases affecting the big toes, it is likely that the precipitating event is a force against the free edge, pushing the nail backwards. Force could be a single episode, or repetitive, as in jogging with cases 4 and 8 or hiking in cases 10, 14, and 15. Poorly fitting or tight-toed footwear, such as high heels, can also be a factor, as seen in cases 16 and 17. In case 2, falling and knocking the nails in the thumb and finger precipitated a similar process. Case 5 illustrates that it is possible for the problem to be initiated by a combination of local distortion associated with arthritis and a systemic event that gives rise to a Beau’s line, representing the break between an old and new nail. In an effort to correlate the experience of surgical avulsion with the pathogenesis, and explain why these nails are not just shed typically following trauma or in instances of onychomadesis, we noted that the uppermost nail appeared to have unusually firm attachment to the nail bed and nail folds. In some cases, this attachment was between the nail plate and distal nail bed; in others, the attachment was between the lateral horns of the nail plate and the sulcus of the nail fold. It may be that where such adherence is stronger, the normal shedding process progresses
abnormally. Alternatively, there could be a baseline defect in the proximal nail fold; if it normally acts as a restricting band holding down the proximal nail plate, where it is diseased the nail can be forced upwards and be predisposed to retronychia.
CONCLUSION We conclude that retronychia (‘‘retro’’—Latin for backwards; ‘‘onychia’’—Greek for nail) is a useful term describing a combination of proximal nail plate ingrowth into the proximal nail fold that is associated with multiple generations of nail plate misalignment beneath the proximal nail and is usually precipitated by trauma. There is a sizeable literature demonstrating that avulsion alone is not useful as treatment of lateral ingrowing nail.10 By contrast, retronychia is a nonrecurrent pathology and, once treated with avulsion, it resolves without complications or relapse. Referrals were kindly provided by Drs L. De Raeve, from the Vrije Universiteit Brussel, Belgium, and by J. Rendall, from Hereford County Hospital, United Kingdom.
REFERENCES 1. Bos AM, van Tilburg MW, van Sorge AA, Klinkenbijl JH. Randomized clinical trial of surgical technique and local antibiotics for ingrowing toenail. Br J Surg 2007;94:292-6. 2. Baran R, Haneke E. Matricectomy and nail ablation. Hand Clin 2002;18:693-6. 3. de Berker DAR, Rendall JRS. Retronychia—Proximal ingrowing nail. J Eur Acad Dermatol Venereol 1999;12(suppl 2):S126. 4. Scher RK. Surgical avulsion of nail plates by a proximal to distal technique. J Dermatol Surg Oncol 1981;7:296-7. 5. Zook EG, Baran R, Haneke E, Dawber RPR. Nail surgery and traumatic abnormalities. In: Baran R, Dawber RPR, de Berker DAR, Haneke E, Tosti A, eds. Nail diseases and their management (3rd ed). London: Blackwell Science, 2001. pp. 425-514. 6. Campbell JP, Grekin RC, Ellis CN, Matsuda-John SS, Swanson NA, Voorhees JJ. Retinoid therapy is associated with excess granulation tissue responses. J Am Acad Dermatol 1983;9: 708-13. 7. Higgins EM, Hughes JR, Snowden S, Pembroke AC. Cyclosporin-induced periungual granulation tissue. Br J Dermatol 1995;132:829-30. 8. Bouscarat F, Bouchard C, Bouhour D. Paronychia and pyogenic granuloma of the great toes in patients treated with indinavir. N Engl J Med 1998;338:1776-7. 9. Hu JC, Sadeghi P, Pinter-Brown LC, Yashar S, Chiu MW. Cutaneous side effects of epidermal growth factor receptor inhibitors: Clinical presentation, pathogenesis, and management. J Am Acad Dermatol 2007;56:317-26. 10. Rounding C, Bloomfield S. Surgical treatments for ingrowing toenails. Cochrane Database Syst Rev 2005;18: CD001541.