Cerebral metastasis from anal squamous cell carcinoma: A case report and literature review.

Anal cancer comprises only 3% of all gastrointestinal malignancies, of which only a small proportion of patients will experience distant metastasis; very few of these cases will metastasise to the brain. The present case report details the clinical course of a 56-year-old female patient who was previously diagnosed with anal squamous cell carcinoma (SCC) and subsequently developed an isolated cerebral metastasis ~5 years later. The patient was initially diagnosed with anal SCC after presenting with a non-tender lump in the groin and had no other signs or symptoms. After undergoing a lumpectomy in 2017, the patient was lost to follow-up. In 2022, the patient presented with a perforated rectal tumour and consequently underwent a loop colostomy followed by chemoradiotherapy. The patient was considered to be in remission at the end of 2023 until subsequent presentation months later with vague neurological symptoms, which led to the diagnosis of a large metastatic lesion in the right temporal lobe. Following resection via craniotomy and additional radiation therapy, there was no evidence to suggest recurrence of either the anal primary tumour or cerebral metastasis from follow-up imaging 5 months post-operatively. The present report highlights the potentially aggressive nature of anal SCC, late-onset cerebral metastasis and the need for further investigation into standardising treatment protocols and surveillance strategies for gastrointestinal metastatic disease.