Colorectal adenocarcinoma metastasis to palatine tonsil as the first presentation: A case report and literature review

Metastases account for only 0.8% of all tonsillar malignancies and the lung, breast, kidney and melanoma are the commonest primary sites. Metastasis of colorectal carcinoma to the palatine tonsil is rare. We report of a 73‐year‐old man who presented with metastatic colorectal carcinoma in the right tonsil as the first presentation; the primary colorectal adenocarcinoma was diagnosed retrospectively. On magnetic resonance imaging, a 3.45 cm tumour was identified in the right oropharynx with associated lymphadenopathy. Tonsillectomy histology confirmed metastatic colorectal adenocarcinoma. On further imaging, an 8cm mass was identified in the sigmoid colon and a biopsy confirmed a poorly differentiated adenocarcinoma. The patient received two cycles of palliative chemotherapy but died 5 months following presentation. Literature review identified 13 case reports in the English scientific literature and clinicopathological analysis of these is presented. The mean age was 55.21 years (age range – 37–81) with male predominance. Half of the patients had a primary tumour in the rectum. Tonsillar involvement was either primary presentation or has been present at the time of diagnosis of primary colorectal tumour in five cases; in all of these, the differentiation of tumour was poor and 3/5 had signet ring morphology. These tumours showed poor prognosis and the life expectancy was 6–15 months irrespective of the type of treatment. This case highlights the importance of considering metastatic carcinoma in the differential diagnosis even at unlikely sites.