Collision tumour of pancreas: a case report with review of literature

Collision tumours are rare tumours; defined as tumours composed of two histologically distinct neoplasms located in the same organ or anatomical site. According to the World Health Organisation (WHO) histological classification, collision tumours include at least two different malignant components, without mixed or transitional area. Collision tumours are different from the mixed tumours formed by more than one type of neoplastic tissue, but, having the same histological origin, as shown by the transitional area. Pathogenesis of this rare entity remains unclear, although there are several proposed hypotheses. Preoperative diagnosis of collision tumours is difficult because of the lack of specific clinical symptoms and radiological features. Histological diagnosis also poses a significant problem and Immunohistochemistry needs to be done in all the cases to reach the conclusion. We, hereby, report a case of 60 year male having Pancreatic head Neuroendocrine carcinoma and Ductal Adenocarcinoma collision tumour. Based on our case report and review of literature, we conclude that collision pancreatic cancer is a very uncommon tumour which poses a significant challenge in diagnosis and treatment.