Treating A Patient With A Nail Unit Tumor

A 14-year-old male who plays football and basketball presents with what he believes is another toenail growing on top of his nail. It is an isolated mass superficial to the hallux nail plate that has been present for about six months.

   The mass is painful when the patient is in various shoes. It does not bleed or have any open areas. The patient has no pertinent past medical history, is taking no medications and has no history of this on any other digit.

   The exam reveals a broad, flattened lesion with a hyperkeratotic tip that is located between the proximal nail fold and nail plate proximally. His nail plate has compensated for the presence of this lesion by a central depression. No lesions are present on the other toenails or fingernails. There are no vesicles, target lesions, purpura or ulcers.

Key Questions To Consider

1. What are the characteristic skin lesions in this condition?
2. What is the most likely diagnosis?
3. What is your differential diagnosis?
4. What is the characteristic nail deformity with this condition?
5. What is the treatment?

Answering The Key Diagnostic Questions

1. The characteristics most associated with this skin condition include a singular flesh-colored, protruding nodule that occurs at the lateral nail folds subungually or from the proximal nail fold.
2. The most likely diagnosis is acquired periungual fibrokeratoma.
3. Differential diagnoses include: acquired digital fibrokeratoma, cutaneous horn, keloid, hereditary digital fibrokeratoma (Koenen’s tumor) or wart.
4. The characteristic nail deformity with this condition is the deformation of the nail plate if the fibromatous lesion is pressing on the nail matrix. There may also be thinning of the nail plate.
5. Treatment generally consists of an excisional biopsy.

A Guide To The Differential Diagnosis

Cutaneous horn. A horn-like projection above the skin that consists of compacted keratin may have at its base a benign lesion or a malignant entity.1 Clinicians have described it as forming over hyperproliferative lesions such as warts, seborrheic keratoses and actinic keratoses. Squamous cell carcinoma is the most common malignancy found at the base of these lesions. An excisional biopsy of the lesion is diagnostic and can be curative.

   Keloid. A keloid is an overgrowth of fibrous tissue that develops after an injury or a surgical procedure. The hallmark of a keloid is that the lesion extends beyond the original margins of the wound or injury. The prevalence is higher in young females versus young males, most likely due to the frequency of ear piercing in adolescent females. Keloids may be painful and a cosmetic concern. If they occur over a joint, keloids may cause contracture, which can reduce range of motion. There are numerous treatments that range from corticosteroid injections to laser therapy to topical therapy with silicone sheeting.

   Hereditary digital fibrokeratoma (Koenen’s tumors). In 50 percent of tuberous sclerosis cases, these lesions develop on both fingernails and toenails.2 Individual lesions are flesh colored with a smooth surface and a hyperkeratotic tip, which makes them difficult to distinguish from an acquired fibrokeratoma. They appear around the age of 12 and increase in number and size as time progresses. Koenen’s tumors typically arise from the nail fold and may destroy or thin the nail plate over time as the lesions multiply and enlarge. Debridement of nails can be challenging in the presence of multiple lesions on the nail. Simple excision at the base of the lesion assists in management of these lesions.

   Wart. Verrucae are a result of human papillomavirus (HPV) infection of the epithelium. These benign, hyperproliferative lesions typically have a hyperkeratotic covering and are flesh colored. Periungual verrucae can cause damage to the nail unit depending on the location.3 They can present on both fingernails and toenails. A wart often stems from nail biting and may recur after treatment. Management of these lesions can range from topical therapy (cryotherapy, salicylic acid) to surgical excision.

What You Should Know About Fibromas

The clinical diagnosis was acquired periungual fibrokeratoma. Fibromas are generally slow growing, painless tumors of the nail unit that can develop in any subepidermal structure. True fibromas are smooth and have a pea-like appearance. If occurring near the nail matrix, they will generally cause nail dystrophy. Depending on the location of the tumor, the nail dystrophy may manifest as nail thinning or as a depression in the nail plate.

   Acquired periungual fibrokeratomas are histologically separate from true fibromas but also may cause nail plate dystrophy. These benign nodules have a hyperkeratotic tip, emerge from the proximal aspect of the nail unit and are thought to be caused by trauma.4 In addition to their flattened flesh-colored appearance on the superficial aspect of the nail plate, acquired periungual fibrokeratomas may also have a filamentous, rounded appearance, which has caused some practitioners to call these lesions “garlic clove” fibromas.

   It is unknown how frequently these occur. Since there is no reporting system for these lesions, a review of the literature yields numerous case presentations. Acquired periungual fibrokeratomas present in both sexes and reportedly occur in people ranging from 12 to 70.5 In younger children, it may represent a supernumerary digit.

Pertinent Pointers On The Treatment Plan

The aforementioned patient and his parent consented to an excision of the lesion. I explained to the patient that after removing the tumor and subsequently reducing pressure on the matrix that the nail may grow back without the depression.

   I also explained to the patient that the tumor may recur due to the continuing trauma from sports or not excising it completely. In order to visualize the most proximal border of the lesion, I incised and dissected the proximal nail fold. I excised the lesion in toto and sent it for histopathologic examination. I sutured the proximal nail fold in place and gave wound care instructions.

   Following the excision, the patient had an uneventful postoperative course. The six-month follow-up visit showed nail plate restoration at the site of the excised lesion and no recurrence. The patient then received a prescription for a topical product consisting of poly-ureaurethane 16% (Nuvail, Innocutis) to assist in filling in ridges and provide protection from everyday trauma.

   Biopsy is recommended for nail unit tumors as entities such as Bowen’s disease (squamous cell carcinoma in situ) can masquerade as periungual fibrokeratoma. In cases such as this one, surgical excision was both diagnostic and curative.

   Dr. Vlahovic is an Associate Professor and J. Stanley and Pearl Landau Fellow at the Temple University School of Podiatric Medicine.

References
1. Solivan GA, Smith KJ, James WD. Cutaneous horn of the penis: its association with squamous cell carcinoma and HPV-16 infection. J Am Acad Dermatol. 1990; 23(5 Pt 2):969-72.
2. Devi B, Dash M, Behera B, Puhan MR. Multiple Koenen tumors: An uncommon presentation. Indian J Dermatol. 2011; 56(6):773-5.
3. Patidar S. Combination treatment of periungual warts. J Cutan Aesthet Surg. 2008; 1(1):23–24.
4. Bart RS, Andrade R, Kopf AW, Leider M. Acquired digital fibrokeratomas. Arch Dermatol. 1968; 97(2):120-9.
5. Baykal C, Buyukbabani N, Yazganoglu KD, Saglik E. Acquired digital fibrokeratoma. Cutis. 2007; 79(2):129-32.