Primary cutaneous phalangeal neuroendocrine/squamous cell carcinoma with mixed axillary metastasis

Cutaneous neuroendocrine tumours are rare and aggressive tumours associated with advanced age and immunosuppression. They are typically characterised by a high rate of local recurrence and nodal disease. The presence of a mixed squamous cell component is rare. These tumours are uncommonly found on the hand. We present a case and histological images of a 78-year-old woman with a primary CK20 negative TTF-1 positive cutaneous neuroendocrine tumour with squamous dedifferentiation arising from the fifth digit with axillary metastasis showing a mixed phenotype. Initial biopsy of the lesion was positive for chromogranin, synaptophysin and TTF-1, but negative for CK20, Melan-A and S100. After CT of the thorax abdomen and pelvis and octreotide single positron emission CT demonstrated a 15 mm axillary metastasis and no evidence of distal disease, our patient underwent an amputation of the affected digit and an axillary lymph node dissection. She is currently awaiting adjuvant chemoradiotherapy. Only two cases are reported in the literature to have mixed squamous/neuroendocrine features. We present the first case which is CK20 negative and TTF-1 positive.