A case of microcystic adnexal carcinoma under the mental region skin in a patient with the chief complaint of trismus

Microcystic adnexal carcinoma (MAC) is a relatively rare malignant tumor originating from the cutaneous adnex.Generally, they grow slowly and have a good prognosis; however, it is a tumor that exhibits strong local infiltration and a high recurrence rate.We report a case of MAC occurring under the skin of the mental region in an 87-year-old patient who came to our hospital with the chief complaint of trismus.She had noticed an induration under the skin of the right mental region for approximately 10 years before the patient' s first visit.Although the mass gradually increased in size, she left it untreated.Several days ago she noticed worsening trismus, fever, and swelling on the right side of her cheek, so she visited our department with these complaints.At the first examination, there was diffuse swelling in the right cheek, and the mouth opening was 15 mm.There were relatively well-circumscribed subcutaneous indurations measuring approximately 180 60 mm on the bilateral lower lip, mental region, and right cheek, and a lower lip mucosal biopsy was performed after the inflammation subsided.Consequently, the patient was diagnosed with MAC and the treatment plan was best supportive care.Two years and three months have passed since the initial visit and the patient is currently under follow-up on an outpatient basis.