Thermoplastic Mask-Induced Contact Dermatitis: A Case Report.

Thermoplastic masks are commonly used in radiation therapy to immobilize a patient's head and neck during treatment. They are primarily composed of non-toxic polyester compounds that can be manipulated with heat to mold the shape of a patient's head and neck. There is little previously reported evidence of these masks causing allergic contact dermatitis. We present a case of a 44-year-old female with a history of squamous cell carcinoma of the right tonsil with multiple enlarged lymph nodes following surgical excision of the right tonsillar mass and ipsilateral neck dissection elected to undergo adjuvant radiation therapy with volumetric modulated arc therapy (VMAT) technique without concurrent chemotherapy. A thermoplastic mask was issued prior to radiation therapy. Following the mask fitting, the patient developed an allergic contact dermatitis reaction of the head and neck in areas covered by the mask. Her symptoms worsened with continued use of the thermoplastic mask and radiation therapy. As the patient continued and eventually finished the radiation treatment regimen, the dermatologic symptoms failed to respond to topical facial moisturizer and steroid treatment. The contact dermatitis reaction did not completely dissipate until about three months following completion of radiation therapy and contact with the thermoplastic mask. Thermoplastic masks are not known to cause an allergic contact dermatitis reaction. There is only one other reported case documented in the literature. Such reactions can alter the course of radiation therapy if symptoms are severe enough to disrupt treatment or if they cause worsening of the radiation dermatitis. Allergic contact dermatitis to thermoplastic masks should be well documented in the future to better understand the cause and possible risk factors related to the reaction.