Primary squamous cell carcinoma of pancreas in a patient with Kaposi sarcoma: A rare case report

Primary squamous cell carcinoma (SCC) of the pancreas is an exceptionally rare malignancy, accounting for a very small proportion of pancreatic neoplasms. Its diagnosis requires exclusion of metastatic SCC from another primary site and other pancreatic tumours with squamous differentiation. We report the case of an 83-year-old man with a background of HIV-negative Kaposi sarcoma (KS), previously treated with liposomal doxorubicin and paclitaxel, who was found to have an incidental pancreatic uncinate process mass on surveillance imaging. Endoscopic ultrasound-guided biopsy demonstrated carcinoma with squamous features, and positron emission tomography-computed tomography excluded an extrapancreatic primary source, supporting a diagnosis of primary pancreatic SCC. Due to frailty and comorbidities, the patient was not considered suitable for surgical resection and was treated with gemcitabine-carboplatin chemotherapy followed by MRI-guided adaptive radiotherapy, achieving an initial radiological response. However, subsequent imaging demonstrated disease progression, and he later died following a catastrophic internal gastrointestinal haemorrhage. This case highlights the diagnostic complexity and aggressive clinical behaviour of primary pancreatic SCC, particularly when arising in a patient with another rare malignancy under active oncological surveillance. • Primary squamous cell carcinoma of the pancreas is an exceptionally rare and aggressive malignancy. • A new pancreatic lesion in a patient with Kaposi sarcoma may represent a second primary tumour rather than metastatic disease. • EUS-guided biopsy and PET-CT were crucial in establishing the diagnosis of primary pancreatic SCC. • The patient initially responded to systemic therapy but later developed fatal internal haemorrhage related to disease progression. • This case emphasises the importance of multidisciplinary assessment in diagnostically challenging pancreatic lesions.