New York — The case of a young adult patient presenting with an extensive plaque of squamous cell carcinoma is of interest because of the puzzling etiology of the malignancy and the therapeutic challenge it presented, his physicians say.

The patient is a 29-year-old man of Hispanic origin who presented to David Kriegel, M.D., associate clinical professor of dermatology, Mount Sinai School of Medicine, New York, complaining of "blemishes" on his forehead that he found cosmetically displeasing. The lesion appeared as a well-demarcated ,eczematous, sandpaper-like plaque covering about
70 percent of the forehead. According to the patient, the eruption was first noticeable about 15 years earlier, but its size had recently increased. Medical attention had never been sought previously.

The area of involvement measured about 10.5 cm by 2.5 cm. Three shave biopsies obtained from various sites were consistent in revealing squamous cell carcinoma, superficially invasive, arising in actinic keratoses.

"Given the low incidence of squamous cell carcinoma in the pediatric and young adult population, the appearance of this extensive, but isolated, plaque with an onset at about age 14 was very perplexing," says Rebecca Kleinerman, M.D., resident, Mount Sinai School of Medicine, New York.

"The size of the malignancy also presented a therapeutic challenge. Mohs micrographic surgery would be the treatment of choice for this type of lesion, but was undesirable, because it would be too cosmetically disfiguring. Therefore, a treatment plan was developed to initiate intervention using topical immune-response modifier therapy and photodynamic therapy, with the hope of shrinking the lesion so that surgery would become more feasible."

After postponing treatment for five months after diagnosis, the patient began nightly application of imiquimod 5 percent cream (Aldara, Graceway) that was continued for eight weeks. The patient admitted omitting the application some nights because of tolerance issues, but the recommended frequency of application was not adjusted.

As of March 2009, the patient had undergone the first of three planned sessions of photodynamic therapy with 5-aminolevulinic acid (Levulan Kerastick, Dusa Pharmaceuticals). At his most recent visit, the plaque had shrunk considerably, supporting the plan to eventually address residual disease with Mohs micrographic surgery.

"There have been a few reports of topical imiquimod treatment for superficially invasive squamous cell carcinoma, although most published information describes treatment of actinic keratoses and in situ disease.

"Similarly, photodynamic therapy is recommended for treating actinic keratosis and squamous cell carcinoma in situ, but consensus groups reviewing guidelines for this intervention have concluded there is insufficient evidence to support its use for superficially invasive SCC," Dr. Kleinerman tells Dermatology Times.

"However, in this unusual case, considering the indolent course to date and the large area of involvement, it seemed reasonable to use these modalities for initiating treatment with a 'light touch.'"

Viral etiology has not been ruled out in the actinic damage and malignant conversion. In particular, epidermodysplasia verruciformis (EV) is considered a possible diagnosis, although there was no evidence of human papillomavirus in the biopsy specimens, nor was the forehead eruption consistent with the EV phenotype.

Disclosure: Neither Dr. Kleinerman nor Dr. Kriegel has any financial interest in the products discussed.