Introduction: Tuberculosis can involve any part of the gastrointestinal tract or the peritoneum and is the sixth most frequent site of extrapulmonary involvement. The pseudotumoral form is relatively rare and several predisposing factors are mentioned, a significant differential diagnostic problem with malignant tumor pathology is exposed , often considered first when encountering an abdominal or pelvic mass in the context of overall deterioration. Presentation of case: We report a rare case of a huge retroperitoneal TB abscess mimicking an abdomino-pelvic cystic mass. Discussion: Abdominal tuberculosis represents 1 to 2% of all locations and 31 to 58% of abdominal locations. The pseudotumoral form is relatively rare and are uncommon in immunocompetent patients. Tuberculosis abscess can present with variable radiologic features. It is difficult to differentiate it from malignant pathologies. Invasive explorations, such as laparoscopy or laparotomy, play a crucial role in confirming the diagnosis. Peritoneal cavity exploration may reveal whitish granulations, peritoneal nodules, peritoneal hyperemia, filamentous peritoneal adhesions, and intestinal adhesions. Histological examination of biopsies are the key to the diagnosis. The treatment of peritoneal tuberculosis relies on a combined therapy of antitubercular drugs . Conclusion: As TB remains endemic in our country and with the continued increase in multidrug-resistant TB infections, it is important to know various presentations and diagnosis forms features of extrapulmonary TB including TB abscess as the treatment remains basically the same combining anti-tuberculosis drugs and the recourse to surgery.