Objective:Rare disease Background:Retroperitoneal sarcomas are rare tumors, only affecting 2 to 5 people per million population and accounting for 0.1% of all malignancies. Liposarcoma is the most common of all retroperitoneal sarcomas, responsible for approximately 20% of all sarcomas in adults. The most important prognostic factors are tumor grade, the presence of positive margins, tumor integrity, and degree of resection. Case Report:Our patient was a 73-year-old man with abdominal pain whose CT scan of the abdomen and pelvis demonstrated a 15×15 cm heterogeneous, left-sided intra-abdominal mass. He underwent resection of the retroperitoneal tumor, left colectomy, and left nephrectomy. Final pathology demonstrated a high-grade, de-differentiated liposarcoma with a rhabdosarcomatous component. The postoperative course was complicated by a small intra-abdominal abscess and abdominal dehiscence. a CT scan after surgery showed a residual tumor of the retroperitoneal posterior margin. Re-exploration to resect the residual tumor and repair the fascial dehiscence were performed. The patient underwent an initial chemotherapy regimen with doxorubicin, then moved to targeted therapy with Palbociclib, and is now on chemotherapy using Eribulin. Conclusions:Achieving complete resection and the grade of the tumor at diagnosis are the 2 most important prognostic factors for patient survival in retroperitoneal liposarcoma, as survival rates are inversely proportional to the grade of the tumor. Even with the best resection attempts, there is always a risk of residual tumor cells within the tumor bed, which contribute to recurrence and need for additional surgical interventions. It is important to approach this disease process with a multidisciplinary team that includes surgical, medical, and radiation oncology to ensure the best survival outcomes. Retroperitoneal sarcoma recurrence and survival are directly related to the ability to achieve negative margins of resection, as well as the grade and size of the primary tumor. Adjuvant therapies that include radiation and immunotherapy may be effective in treating recurrent disease.

Gallbladder agenesis is a congenital anomaly that often presents with symptoms of biliary colic. Due to the rarity of this condition, it is often difficult to diagnose pre-operatively. Here we present a case of a 33-yo female with a 6-month history of right upper quadrant abdominal pain and associated nausea. With false-positive imaging findings of cholelithiasis on ultrasound examination, an incidental intraoperative diagnosis of gallbladder agenesis was made during a routine elective laparoscopic cholecystectomy. This finding was confirmed with postoperative magnetic resonance cholangiopancreatography. The primary aim in reporting this case is to further promote awareness of this rare condition out of concern for increased risk of iatrogenic operative injury in the setting of a condition where conservative management is recommended.