Gastrointestinal (GI) stromal tumors (GISTs), although rare, are the most common mesenchymal tumor of the GI tract. They comprise approximately 80% of all GI mesenchymal tumors and most commonly occur in the stomach and small bowel1. GISTs originate from interstitial cells of cajal (ICCs), mesenchymal cells located within the muscular layer of the GI tract, which generate electrical pacemaker activity for gut motility. These cells express the KIT protein on their cell surface, and GIST almost universally stain positive for the KIT protein by immunohistochemical staining. We present a case of this uncommon tumor and review the literature.

Pseudomyxoma peritonei is a rare condition, characterized by gelatinous ascites of the abdominal and pelvic cavities accompanied by mucinous implantations of the peritoneum and omentum. It is usually presented as a disseminated mucinous tumor with dissection of the abdominal and pelvic organs producing pseudomyxoma peritonei. Mucinous implants usually involve the serosal surface of multiple pelvic and abdominal organs. Although it is accepted that most investigators believe that the ovarian tumors are secondary in almost all cases to a primary appendiceal tumor, a synchronous origin in both organs has also been proposed. The agreement on the association of certain tumor morphologies with certain behaviors is persistently plagued by disagreement regarding tumor nomenclature and classification. We present a case of recurrent pseudomyxoma peritonei and review the literature of nomenclature, classification, diagnosis, and management of these tumors.

Gastric cancer (GC) is one of the most common cancers by incidence and number of deaths. Gastric cancer is more prevalent in males with the strongest risk factor being Helicobacter pylori infection. Signet ring cell adenocarcinoma (SRCA) is a subtype of GC associated with a worse prognosis due to late presentation. SRCA is more likely to be metastatic at presentation compared with other subtypes of GC. We present a case of metastatic gastric SRCA presenting as a colonic mass with associated ascites and pleural effusion. This case highlights the importance of including metastatic gastric SRCA in the differential diagnosis in patients presenting with gastric and colonic dual SRCA. It is vital to determine if it is a metastatic tumor or two primaries as this would change staging and treatment protocols.

Angiomyolipomas (AMLs) are benign mesenchymal tumors of generally unknown origin, that consist of mature adipose tissue, smooth muscle fibers and blood vessels with thickened wall, most commonly seen arising in the kidney. Angiomyolipomas comprise about 1% of all renal masses. In contrast, extrarenal retroperitoneal AMLs represent extremely rare tumors with fewer than 100 reported cases. Colon angiomyolipomas is considered a rare site of this tumor. They are usually asymptomatic and present a unique diagnostic challenge since they can mimic other benign and malignant tumors, which must be differentiated. We report a case of a 58-year-old female with submucosal polypoid sigmoid lesions. Histopathological examination was diagnostic of colonic angiomyolipoma. We discuss differentiation of this entity from other tumors and we provide brief review of the literature