Key clinical features differentiate nail tumor types

Because there are a variety of nail tumors, both benign and malignant, recognizing the key clinical features of each will help the dermatologist treat and/or surgically intervene as needed.

Also, as with most cutaneous neoplasia, surgical removal – either via Mohs micrographic surgery or simple excision – is often the treatment of choice.

One of the more common tumors of the nail apparatus is squamous cell carcinoma, which mostly affects men and has a peak incidence between 50 and 69 years of age.

“Many of these tumors are associated with human papillomavirus (HPV) infection, predominately HPV 16, but also including HPV 2, 11, 18, 26, 31, 34, 35, 56, 58 and 73,” says John Montgomery Yost, M.D., M.P.H., a clinical assistant professor of dermatology at Stanford University.

Other risk factors for squamous cell carcinoma are immunosuppression, trauma, tobacco use, oral exposure to arsenic and pesticides, dyskeratosis congenital, as well as ultraviolet radiation.

The presentation of this particular malignancy can vary significantly, depending on its location.

“Subungual tumors classically present with subungual hyperkeratosis, onycholysis and nail plate dystrophy, and longitudinal erythronychia, while periungual squamous cell carcinomas, which affect the nail folds rather than the nail bed or matrix, are often characterized by hyperkeratotic, verrucous papules and plaques, or less commonly paronychia,” Dr. Yost tells Dermatology News. He presented on nail tumors at the 2017 American Academy of Dermatology (AAD) annual meeting in Orlando, Fla.

“In the absence of bony involvement or extension into the bone, Mohs micrographic surgery is the gold standard for surgical management for this type of tumor,” Dr. Yost says. “Results are excellent.”

Onychomatricoma

Onychomatricoma is a second distinct tumor of the nail apparatus.  Although relatively rare, these neoplasms are most often seen in middle-aged patients and have no gender predisposition.

Clinically, onychomatricomas typically present with discrete nail thickening, xanthonychia, splinter hemorrhages, and increased transverse curvature of the nail plate. “Often, many small holes can be seen within the nail at the distal free edge,” Dr. Yost says “This characteristic finding, resembling a honeycomb, represents filamentous projections of the primary neoplasm extending into the nail plate.”

Initially, the tumors were believed to potentially transform into malignancies. “However, now it is pretty well understood that there is no malignant potential of these lesions,” Dr. Yost says. “Simple surgical excision is curative.”

Still, even with surgical intervention, there may be some resulting scarring of the nail matrix. “Any surgical intervention involving the nail plate can produce some degree of onychodystrophy, often manifested by a split or crack in the nail plate,” Dr. Yost says.

Onychopapilloma

Onychopapilloma is another benign neoplasm of the nail matrix. Relatively rare, it similarly affects both genders equally. “Like most tumors of the nail apparatus, the tumor is more common in middle-aged and elderly adults,” says Dr. Yost, director of the Nail Disorders Clinic at Stanford.

These neoplasms often present with longitudinal erythronychia or longitudinal leukonychia, arising from a well-defined visible erythematous macule in the lunula, or distal nail matrix.

Clinically, onychopapillomas may be associated with some tenderness, often caused by pressure or palpation. “However, rarely do these tumors cause any degree of significant pain on their own,” Dr. Yost says.

“No intervention is necessary,” Dr. Yost notes. “But if the tumor is symptomatic, a surgical excision is recommended. However, as with onychomatricomas, excision of these lesions may result in permanent nail dystrophy, representing scarring of the nail matrix, either from the neoplasm itself or the resulting surgical intervention.”

Glomus tumors

Glomus tumors represent a fourth subtype of neoplasia affecting the nail unit. These lesions often present clinically as a subungual blue to red macule, and are frequently associated with pain, tenderness, and most importantly temperature sensitivity. “There is classically increased pain with extremes in hot or cold,” Dr. Yost says. “For the purpose of clinical diagnosis, cold water or ethyl chloride is often helpful and should cause or exacerbate any associated pain.”

Glomus tumors can result in some degree of bony erosion; therefore, prior to any intervention, “I would recommend some kind of imaging, whether x-ray or MRI,” Dr. Yost says. “Ultrasound has also been used, but there is less data supporting efficacy.”

If there is no extensive erosion into the bone, surgical excision is the treatment of choice.

Because glomus tumors can be relatively large, a repair of the nail bed may be required. “In many instances, this necessitates the full avulsion of the nail plate,” Dr. Yost says.

Surgical excision for all four types of tumors yield “largely successful results,” Dr. Yost says. However, if not completely excised, all may recur.

“With our unique experience in clinical diagnosis of nail disorders and neoplasia of the nail apparatus, dermatologists are in a singular position to manage nail tumors,” Dr. Yost concludes.

Dr. Yost reports no relevant financial disclosures.