Metachronous triple primary malignancies of duodenum, skin, and appendix in the absence of common hereditary syndromes: a case report.

Multiple primary malignancies (MPMs) are a more severe and common problem to exist in the field of clinical Oncologist. The case of a 61-year-old male with three metachronous primary cancers over a span of 36 months: duodenal mucinous adenocarcinoma, facial basal cell carcinoma, and appendiceal goblet cell adenocarcinoma. In 2021 the patient initially visited the hospital with clinical features consistent with acute cholangitis, which was later determined through a comprehensive series of examinations, such as computed tomography (CT), magnetic resonance imaging (MRI), and endoscopic biopsy, to be a duodenal adenocarcinoma, thus undergoing pancreaticoduodenectomy followed by adjuvant FOLFOX (folinic acid + fluorouracil + oxaliplatin) chemotherapy. Subsequently, a facial basal cell carcinoma was excised in 2022, and an appendiceal goblet cell adenocarcinoma was discovered by chance during appendectomy for a suspected abscess in 2023, so further FOLFOX chemotherapy was administered. Duodenal tumor showed mismatch repair (MMR) proficiency and wild-type p53 by immunohistochemistry but germline testing was not performed. This case shows that MPM can imitate common benign diseases, need to do a thorough investigation, highly vigilant. To establish criteria of clinicopathological stringency, and showed that the possible defining characteristic in the absence of any specific inherited syndromes was probably chronic inflammation which acted as "common soil". Radical surgery and one consistent chemotherapeutic regimen for two adenocarcinomas, a practical route. Finally, it's stated in this report here that comprehensive long-term multimodality follow up in all the cancer survivors should be done to get the early new primary malignancies.