A 6-year-old male who likes to play sports presents with painful great toenails that have been present in the current condition since birth. They are painful in various shoes. His mother has taken him to other physicians who stated that the condition is not caused by nail fungus but they have offered no other solution. The patient has no pertinent past medical or birth history, no medications and no history of this on any other digit.
Upon examination, his bilateral hallux toenails are discolored, thickened, rough in appearance and deviated laterally. No lesions are present on the other toenails or fingernails.
Key Questions To Consider
What are the main characteristics of this condition?
What is the most likely diagnosis?
What is your differential diagnosis?
What is the characteristic nail deformity in this condition?
What is the treatment?
Answering the Key Diagnostic Questions
The characteristics most associated with this nail condition are the lateral deviation of the nail plate with transverse ridging of the hallux toenail.
The most likely diagnosis is congenital malalignment of the great toenail.
Differential diagnoses include onychomycosis, onychogryphosis or paronychia.
The characteristic nail deformity in this condition is the dystrophy of the nail plate with a lateral deviation of the nail in comparison to the longitudinal axis of the proximal phalanx.
Treatment ranges from conservative care to a surgical rotation of the misaligned matrix.
What You Should Know About Congenital Malalignment of the Great Toenails
Samman and colleagues first described congenital malalignment of the great toenails in 1978 as a great toenail “dystrophy” in newborns.1 Baran and colleagues further defined it as “congenital malalignment of the big toenail” a year later.2 Few case studies exist so determining the frequency of the condition is difficult. Judging from the literature that reports patient characteristics, it appears females are more affected than males. A genetic component has been hypothesized but Baran and coworkers felt that an abnormal pull of the extensor hallucis tendon causes the lateral portion of the nail matrix to be displaced proximally.2 This has the validation of magnetic resonance imaging (MRI) studies, which showed a hypertrophy of the dorsolateral aspect of the extensor tendon.3,4
The hallmark of this nail condition is a lateral deviation of the nail plate with respect to the distal phalanx’s longitudinal axis that is present at birth.5 The nail loses its natural color and presents as yellow, green, gray, black or brown. If green discoloration is present, there may be Pseudomonas colonization. If brown or black discoloration is present, there may be a subungual hemorrhage or fungal infection. Wave-like transverse ridging across the nail plate gives the nail an oyster shell-like appearance. The free end of the nail may appear pointed or triangular. The condition mostly occurs bilaterally with only hallux involvement and may overlap with hallux valgus.
As the nail progresses towards the distal tip, it becomes onycholytic and thickened. As the nail loses contact with the nail bed, a distal wall of skin may build up, which further prevents the nail from growing forward longitudinally. Onychocryptosis and possible paronychia may develop as the nail continues to take its curvilinear path toward the second digit.
A Guide to the Differential Diagnosis
Onychomycosis. Onychomycosis or tinea unguium is caused by invasion of the nail unit by dermatophytes, non-dermatophyte molds, and/or Candida albicans. Clinicians may see concomitant tinea pedis or tinea cruris in patients with onychomycosis.
The most common form of onychomycosis in the lower extremity is distal lateral subungual onychomycosis caused by Trichophyton rubrum. Clinically, it may be difficult to distinguish onychomycosis from other existing nail pathologies. A KOH preparation, periodic acid Schiff (PAS) staining and fungal culture can aid in determining the presence of a dermatophyte-caused infection.
Onychogryphosis. Also known as ram’s horn nails, onychogryphosis results in an extremely elongated, dystrophic, claw-like curved nail that is often related to neglect of performing nail debridement for an extended period of time. Clinicians most often see this in the elderly population. It can also be related to shoe gear and/or biomechanical trauma, which causes one side of the nail to grow faster than the other. Accordingly, there is a characteristic curving of the nail plate.
Paronychia. One of the most common issues that drives patients into the office is paronychia of the great toenail or inflammation of the lateral and proximal nail folds, usually accompanying an incurvated and “ingrown,” or onychocryptotic nail plate. Purulence due to a Staph aureus infection generally occurs with this condition on the feet whereas Candida infection is more common in chronic thumb suckers. Ingrown toenails with accompanying granulation tissue at the lateral nail fold are generally painful and can be malodorous.
Treatment includes topical antibiotic and anti-inflammatory medications; oral antibiotic therapy; taping of the offending nail border to pull the inflamed skin away from the nail; education on proper nail trimming; incision and drainage of the abscess; and surgical removal of the onychocryptotic nail plate with or without chemical matrixectomy (phenol or sodium hydroxide).
Key Treatment Insights
When it comes to congenital malalignment of the great toenails, these nails may spontaneously regress in less than 50 percent of cases.6 Regarding other conservative measures, I also advocate nail debridement, partial nail avulsion if needed and finally taping. Arai and colleagues in Japan have described a simple taping method for onychogryphosis, which one can adapt to this type of dystrophy.7
From a surgical perspective, the best time to correct this deformity is before the age of 2 but I have corrected this condition in adults with success.8 The traditional treatment is a crescent-shaped resection that one carries back proximal to the nail bed and matrix.9 The surgeon would also excise a small triangular shaped area at the start of the proximal lateral incision in order to swing the whole nail unit so one can suture it in the appropriate orientation.
For this patient, I chose nail debridement followed by the Arai technique of taping, which one should repeat on a daily basis. I also prescribed a poly-ureaurethane, 16% nail solution (Nuvail, Innocutis) for the patient to apply nightly in order to create a smoother appearance and protect the nail plate. One should periodically monitor the patient for nail plate changes.