Chapter 8: Nail Contact Dermatitis

SUMMARY

• Nail cosmetics and relative techniques have become increasingly popular but they are not without risks, in particular for the emergence of a new class of allergens called acrylates.

• Acrylates and other known potential allergens or irritants, such as tosylamide and formaldeyde, contained in nail polish, can favor the onset of nail contact dermatitis.

• Nail contact dermatitis can be divided into irritant contact dermatitis with nail plate yellowing, nail dystrophy, and cuticle destruction, or allergic contact dermatitis, with a characteristic psoriasiform reaction of multiple fingernails. In particular situations, other skin body areas may be afflicted.

TIPS FOR DIAGNOSIS

• Irritant nail contact dermatitis is characterized by the prevalence of onycholysis, longitudinal ridging, or chronic paronychia. Usually the proximal nail fold is involved with nail plate surface abnormalities. Also, pterygium inversum unguis and monoliteral koilonychia have been reported.

• Allergic nail contact dermatitis can appear as psoriasiform reactions with onycholysis and mild subungual hyperkeratosis of multiple fingernails. Itch in the nail bed, pain, and occasionally paresthesia can occur.

• In allergic nail contact dermatitis, onychoscopy reveals the presence of a slightly dented onycholytic margin and mild subungual hyperkeratosis and the absence of pitting or erythematous border with salmon oil spot surrounding the distal edge of the detachment, which could instead suggest nail psoriasis.

TIPS FOR TREATMENT

• A proper clinical and allergological history is mandatory to detect triggering factors.

• Patch tests are the gold standard for diagnosis of allergic contact dermatitis.

• Treatment is aimed at reducing potential irritants, avoiding allergens and aggressive cosmetic procedures and educating the patient to use appropriate individual protection systems, treating the inflammation with topical steroids or calcineurin inhibitors, associated with barrier creams and emollients.

DON’T FORGET

• Emerging data confirm the worldwide rising of (meth)acrylate sensitization both in nail technicians and nail product consumers.

PITFALLS AND CAUTIONS

• The presence of acrylates in a wide range of medical materials, including dental implants and prostheses, will pose probable difficulties in the future, especially among young sensitized people, for a reduced access to some medical procedures.

EXPERT PEARLS

• In the case of acute onset periungual dermatitis with/or psoriasiform nail changes in multiple fingernails, a contact dermatitis should be considered.

• Dermoscopy of the onycholytic margin of the nail plate is a fundamental step to distinguish an allergic psoriasiform reaction from nail psoriasis.

• The presence of eyelid dermatitis must always be investigated, asking the patient about nail aesthetic procedures for a risk of airborne contact dermatitis.

PATIENT EDUCATION POINTS

• A proper education about the risk of side effects and sensitization from acrylates is essential when gel nail polish is used by women and manicurists.

• Manicurists should wear preferably nitrile gloves and, for the risk of acrylate-induced airborne contact dermatitis, adequate room ventilation is necessary.

• Prevention of cross-reactions is needed, especially in allergic contact dermatitis induced by acrylates. It is advisable to avoid contact lenses, paint, acrylic fibers, eyelash extensions, ...