2020 Volume 35 Issue 2 Pages 35-40
A 42－year－old woman presented with a postauricular nodule, which was diagnosed as malignant melanoma using lymph node biopsy. She had several brown spots and papules on her head and neck. Papules on the parietal region of the head were diagnosed as pigmented nevi after histopathological examination. Positron emission tomography－computed tomography revealed cervical lymph node metastases ; however, no other distant lesions were found. She underwent cervical lymph node dissection and was subsequently treated with nivolumab for melanoma with unknown primary origin (MUP). However, multiple distant metastases occurred, with a marked increase in her serum lactate dehydrogenase levels. She died 85 days after the operation. Because MUP progressed rapidly, a detailed histopathological re－examination of the specimen was performed and revealed the lesion in the head to be the primary lesion. The rate of BRAF gene mutation is generally high in superficial spreading melanoma ; therefore, treatment with BRAF and MEK inhibitors could be effective. However, high melanin content in the tumor hinders the analysis of BRAF gene mutation.[Skin Cancer (Japan) 2020 ; 35 : 35－40]
