Keywords
pachyonychia congenita - germinal matrix excision - nail bed excision - surgical dermatology
- congenital
Introduction
Pachyonychia congenita (PC) is an autosomal dominant genetic disorder characterized
by hypertrophic nail plates, hyperkeratotic nail beds, and thickened hyponychium of
the fingers and toes.[1] The distal two-thirds of the nail plates become thickened, elevated, and transversely
arched due to hyperkeratosis of the nail bed. The thickened portion often becomes
discolored, resulting in yellow or brown nails. Additional symptoms associated with
PC include leukoplakia, palmar and plantar hyperkeratosis, and epidermal cysts but
vary depending on the genetic variant. Management is often determined by both type
and severity of the keratin genetic mutation.[1] Because of this, the importance of genetic testing prior to treatment cannot be
understated.
Because of the effect PC has on the nail beds, it also impairs manual dexterity and
often leads to surgical referral. Despite increased awareness and ongoing research
into PC, literature regarding the surgical management of the disorder remains limited.[2]
[3] Many treatments for PC focus on pain management with Botox injection and sirolimus,
which has shown some efficacy in managing symptoms.[1]
[4] We present our experience and results of treating a pediatric patient with a combination
of germinal matrix excision (GME) alone, GME with partial sterile matrix excision
(pSME), and GME with complete sterile matrix excision (cSME).
Case
A 3-year-old boy presented with hypertrophic nail growth involving all digits of both
hands and feet ([Fig. 1]). The nails caused persistent pain and discomfort and required frequent trimming.
This patient's parents opted for definitive surgical treatment. No previous genetic
testing was done on the patient.
Fig. 1 Right hand preoperatively. The nail plates show significant thickening on all five
digits.
With no established surgical technique for definitive treatment of the nails, three
varying surgical procedures were performed on the patient's fingers and toes to identify
which would be most effective in preventing painful regrowth. These techniques included
GME alone, GME plus pSME, or GME plus cSME ([Table 1], [Fig. 2]). All nail beds were closed with local skin grafts when unable to be closed primarily.
Table 1
A summary of involved digits, procedures, and outcomes
|
Digits
|
Procedure
|
Outcome
|
|
Right fingers 1, 2, 3, 4, and 5
Right finger 2
|
Germinal matrix excision
Subsequent thinning ⅔ thickness of sterile matrix
|
Mild, slower hypertrophic nail growth in 1, 2, and 3. Hyperkeratinization approximating
normal nail thickness in 4 and 5.
Thinner but still hypertrophic nail
|
|
Right toe 1
|
Germinal matrix excision
Subsequent sterile matrix excision; primary skin closure
|
Recurrent hypertrophic nail growth
Primary skin healing, no nail growth
|
|
Right toes 2, 3, and 4
|
Germinal matrix excision
|
Hyperkeratinization approximating normal nail thickness
|
|
Right toe 5
|
Germinal and sterile matrix excision; primary skin closure
|
Primary skin healing, no nail growth
|
|
Left finger 1
|
Germinal matrix excision
|
Recurrent hypertrophic growth, slight improvement
|
|
Left finger 2, 3, 4, and 5
|
Germinal matrix excision
|
Mild, slower hypertrophic growth
|
|
Left toes 1, 2, and 3
|
Germinal matrix excision
|
Mild, slower hypertrophic growth
|
|
Left toes 4 and 5
|
Germinal and sterile matrix excision; primary skin closure
|
Primary skin healing, no nail growth
|
Fig. 2 Illustration showing a longitudinal cross section of the nail tip and demonstrating
the procedure.
The three toes treated with GME + cSME with proximal nail fold closure exhibited primary
skin healing with no nail growth. This method of treatment was the most successful
([Table 1]). The right hallux, treated with GME alone, exhibited slow but recurrent growth
of the hypertrophic nail. Subsequent cSME and local skin closure resulted in no nail
growth. The remaining toes, treated with GME alone, developed hyperkeratinization
at a slower growth rate than before the operation ([Fig. 3]).
Fig. 3 The right foot 8 months after germinal matrix resection on toes 1, 2, 3, and 4 and
germinal matrix and sterile matrix resection on toe 5. Recurrence of the thickened
nail on the great toe is noted. Subsequent resection of the sterile matrix of the
great toe was curative. Toes 2, 3, and 4 show hyperkeratinization. Toe 5 has no nail
regrowth.
The thumbs exhibited bilateral thickened nail plate growth, though to a lesser degree
than preoperatively. Additionally, the rate of growth was slower. The remaining two
to five fingers exhibited nail plate hypertrophy but less than that of the thumbs
([Fig. 4]). Nail growth was significantly slowed. Before surgery, nail trimming was necessary
every month, but following GME, nail trimming was necessary every 3 to 6 months.
Fig. 4 The right hand 8 months after germinal matrix resection of all five digits. The thumb,
index, and middle show recurrence while the ring and little have hyperkeratinization
approximating the thickness of a normal nail.
Due to recurrent hypertrophy, the thickness of the right index sterile matrix was
thinned by two-thirds, resulting in a significantly thinner nail plate. Improvement
was noted with this method, but the result was not ideal compared with GME + cSME.
These results have persisted for 19 months following surgery.
Discussion
Medical therapy to reduce hyperkeratosis is limited; however, several surgical techniques
have been described to improve the function and appearance of digits with hypertrophic
nail plates. The various methods address the germinal matrix and nail bed separately.
Grinding and milling the nail plates to reduce nail plate thickness (under general
anesthesia) followed by regular maintenance grinding of the nail plates (without anesthesia)
effectively controls nail plate thickness.[5] The ongoing maintenance required for this control must be compared with the benefits
of more permanent interventions. Daroach et al found that nail plate avulsion in combination
with oral sirolimus significantly improved pain, but did not prevent the regrowth
of abnormal nail plates and, consequently, was only of temporary benefit.[4]
[6]
[7]
[8] Control of the hypertrophic nail plates by amputation of the distal phalanx, while
effective, is unacceptably extreme.[9]
Cosman et al reported nail plate, GME, and pSME followed by full-thickness skin graft
coverage with the remaining nail bed developing hyperkeratinization.[10] A more aggressive approach was reported by White and Noone in which the nail plate
was excised with GME and then covered with a split-thickness skin graft.[11] No nail plate growth recurred. Thomsen et al treated different fingers with different
surgical procedures.[6] They concluded that GME or destruction was sufficiently effective in treating the
nail plate abnormalities and that cSME was unnecessary. The remaining nail bed developed
hyperkeratinization, which they felt was acceptable. Vigorous curettage and fulguration
of the germinal and sterile matrices produced smooth nail beds without nail plate
growth on four of the six digits treated. Minimal hyperkeratosis developed on one
nail bed, and a small spicule of recurrent nail plate grew on another. Preservation
of the germinal matrix deep to the eponychium with excision of the distal germinal
matrix and nail bed resulted in thickened nail plate regrowth. Excision was chosen
in place of chemical germinal matrix ablation, seeing that ablation has reduced success
in cases of recurrent nail growth.[12]
[13] A 2020 retrospective study by DeKlotz et al looked at 18 patients who had their
nails removed and found that of the 18 individuals, 13 would recommend nail removal
to others with PC. Most of the patients who had no regrowth of at least one nail would
recommend that treatment.[14] This suggests that if nail removal is to be attempted, finding the process that
would allow minimal regrowth would be of much benefit.
In this patient, the results implicate the involvement of both germinal and sterile
matrix contributing to nail hypertrophy. In the toes treated with GME + cSME, no nail
growth occurred. As Thomsen et al's study also suggests, the thickness of the sterile
matrix remaining may correlate with the amount of hyperkeratinization. The presented
results support this theory.[6] Initial postoperative hyperkeratinization of the right index finger was improved
with thinning two-thirds of sterile matrix thickness. GME with cSME and closure of
the defect secondarily or with a skin graft is a safe and effective option for treating
nail hypertrophy in PC. This option showed to be the most definitive and successful
treatment. An alternative that avoids skin grafting is full-thickness GME and pSME
with thinning two-thirds thickness of the sterile matrix. Patients and their families
should be counseled that some hyperkeratinization may result in preserving one-third
thickness of the sterile matrix. The hyperkeratinization is significantly decreased
compared with preserving the entire thickness of the sterile matrix. This option also
does produce the appearance of a nail plate.
PC is a rare disease, and large cohorts are challenging to find. Although successful,
the surgical management of this rare disorder is described in a single case, potentially
limiting its applicability to all patients afflicted with PC. Therefore, inferences
cannot be made on the most appropriate treatment for all PC patients. This patient
was lost to follow-up prior to completing genetic testing. Therefore, the appropriateness
of this procedure for specific genotypes of PC patients cannot be commented on. Further
studies are needed to assess which exact mutations are appropriate for GME + cSME.
All procedures followed were in accordance with the ethical standards of the responsible
committee on human experimentation (institutional and national) and with the Helsinki
Declaration of 1975, as revised in 2008 (5). Informed consent was obtained from all
patients for being included in the study. Additional informed consent was obtained
from all patients for which identifying information is included in this article.
