Introduction
Neuroendocrine neoplasms originating in the urinary bladder are exceptionally uncommon. According to the latest WHO/ISUP classification from 2016, there are four recognized types of neuroendocrine neoplasms found in the urinary bladder: small cell neuroendocrine carcinoma, large cell neuroendocrine carcinoma, well-differentiated neuroendocrine tumor, and paraganglioma. Small cell neuroendocrine tumors make up less than 1% of malignant bladder tumors, while large cell neuroendocrine tumors represent an even rarer subset [1-3].
In bilharzia-endemic areas, schistosomiasis is a common infection, and it is recognized as a risk factor for squamous cell carcinoma of the bladder. Research indicates that schistosomiasis has also been linked to various other histotypes, such as neuroendocrine tumors of the gastrointestinal tract [4,5]. Admixing of both small cell neuroendocrine and large cell neuroendocrine tumors is rare. However, such a coexistence has been described in a very few patients, but it has not been linked to schistosomiasis [6,7].