Successful treatment of trichilemmal carcinoma with distant metastasis using pembrolizumab: a case report and review

Trichilemmal carcinoma (TC) is a rare, malignant cutaneous adnexal tumor. TC often has nonspecific clinical manifestations and its aggressive nature is frequently overlooked. Metastasis of TC is rarely reported and there is no standard treatment for recurrent or metastatic TC. We report a complicated case of TC arising from the parotid gland with metastasis to cervical lymph nodes. The tumor progressed after multiple surgeries, radiation and chemotherapy. Finally, the patient achieved good response and disease control with pembrolizumab, an immune checkpoint inhibitor targeting programmed cell death protein-1. Currently, the patient has received 19 cycles of pembrolizumab and the disease remains well controlled. This represents the first reported use of immune checkpoint blockade to treat TC. This paper discusses a rare form of skin cancer called trichilemmal carcinoma (TC) and presents a distant metastasis TC case. The patient was treated with an immunotherapy called pembrolizumab and after 19 courses of treatment, the tumor was significantly reduced and the symptoms were relieved. This case report is the first recorded case study of pembrolizumab for the treatment of TC and provides a new approach to the treatment of challenging malignancies. Trichilemmal carcinoma (TC) is a rare malignant cutaneous adnexal carcinoma originating from the outer root sheath of hair follicles, with nonspecific clinical manifestations that can pose challenges in diagnosis and effective treatment. Metastasis of TC is uncommon, and there is currently no established standard treatment for recurrent or metastatic TC. Early-stage TC can be managed with surgery, while recurrent or metastatic TC can be managed with radiotherapy and/or chemotherapy; however, immune checkpoint inhibitors and targeted agents have not yet been reported for TC treatment. The case study presented in the paper details a complex scenario of TC originating from the scalp and spreading to the parotid gland and cervical lymph nodes. Despite undergoing multiple conventional treatments, including surgeries, radiation and chemotherapy, the tumor exhibited progression. Pembrolizumab, an immune checkpoint inhibitor, has demonstrated efficacy in treating advanced and metastatic TC, leading to significant tumor reduction and symptom relief after 19 treatment cycles. This case report signifies the first documented utilization of immune checkpoint blockade therapy, specifically pembrolizumab, in TC treatment. It introduces a novel approach to therapeutic interventions in rare and challenging malignancies. The successful use of pembrolizumab in this case report highlights the potential of immune checkpoint inhibitors as a valuable treatment option for refractory TC cases, offering hope for future treatment strategies.