Mesenteric Cyst as a Diagnostic Pitfall Mimicking Perforated Appendicitis and Causing Generalized Peritonitis: A Case Report
Abstract
Mesenteric cysts are rare and benign intra-abdominal lesions that can mimic acute appendicitis particularly in young patients, posing a diagnostic challenge. We report a multilocular mesenteric cyst causing generalized peritonitis clinically indistinguishable from perforated appendicitis. A 24-year-old man presented with worsening diffuse abdominal pain and anorexia, preceded by a one-week history of migratory epigastric pain and fever. Examination showed generalized tenderness with guarding and rebound tenderness. Laboratory tests revealed marked leukocytosis, neutrophilia, and an elevated neutrophil-to-lymphocyte ratio. Abdominal Xray showed no free air but a mass effect in the right hemiabdomen, presumed to be a periappendiceal inflammatory mass. With an Alvarado score of 8, he underwent emergency laparotomy for suspected perforated appendicitis. A large multilocular mass was found posterior to the ascending and transverse colon, together with suppurative appendicitis and dense adhesions. Mass excision, omentectomy, and appendectomy were performed. Histopathology confirmed a mesenteric cyst with xanthogranulomatous inflammation without epithelial lining or malignancy. The postoperative course involved transient electrolyte disturbances and ileus, both managed conservatively and the patient was discharged in stable condition on postoperative day 5. A high Alvarado score reliably indicates the need for surgical exploration but cannot exclude alternative intra-abdominal pathology with an overlapping presentation. Systematic intraoperative evaluation and complete excision of unexpected masses remain essential for accurate diagnosis and favorable outcomes.
References
Armando, R., Ceballos, G., & Ramírez, I. B. (2025). Giant Mesenteric Cyst : Diagnostic Challenges and Surgical Management in a Clinical Case. Cureus, 17(7), 1–8. https://doi.org/10.7759/cureus.88010
Cercelaru, L., Vîlcea, I., Valeriu, S., Barbu, A., & Vasile, L. (2025). Coexistence of Acute Appendicitis and Mesenteric Cystic Lymphatic Malformation in an Adult : A Case Report and Narrative Review of Intraoperative Management Strategies. Life, 1–18.
Cervantes, B. Y. H., Lopez, D. M., Acevedo, F. M. A., & Benjamin, M. B. (2023). Adult with concurrent mesenteric cyst and acute appendicitis : a case report. Journal of Surgical Case Reports, 1–4.
Clark, J. A., Paal, E. E., & Manning, M. A. (2021). Approach to Cystic Lesions in the Abdomen and Pelvis , with Radiologic- Pathologic Correlation. RadioGraphics, 1368–1386.
Giannis, D., Matenoglou, E., & Moris, D. (2020). Hyponatremia as a marker of complicated appendicitis : A systematic review. The Surgeon, xxxx, 1–10. https://doi.org/10.1016/j.surge.2020.01.002
Hajibandeh, S., Hajibandeh, S., Hobbs, N., & Mansour, M. (2019). The American Journal of Surgery Neutrophil-to-lymphocyte ratio predicts acute appendicitis and distinguishes between complicated and uncomplicated appendicitis : A systematic review and meta-analysis. The American Journal of Surgery, xxxx. https://doi.org/10.1016/j.amjsurg.2019.04.018
Inteti, K., Shaik, M. R., Ganapa, P., & Gandi, P. S. (2024). A Comparison of the Alvarado Score and the Raja Isteri Pengiran Anak Saleha Appendicitis ( RIPASA ) Score in the Diagnosis of Acute Appendicitis : A Prospective Cohort Study. Cureus, 16(8), 8–17. https://doi.org/10.7759/cureus.68041
Khawaja, Z. H., Gendia, A., Adnan, N., & Ahmed, J. (2022). Prevention and Management of Postoperative Ileus : A Review of Current Practice. Cureus, 14(2). https://doi.org/10.7759/cureus.22652
Messias, B., Cubas, I., Oliveira, C., Hashimoto, F., Mocchetti, E., Ichinose, T., Waisberg, J., & Junior, M. A. F. R. (2026). Serum sodium as an adjunct marker of acute appendicitis severity : a retrospective cohort study. BMC Surgery, 2023, 1–7.
Monteiro, D. L., Eiró, F., Contente, H., Branco, C., & Santos, C. (2025). Mesenteric Cyst : A Case Report of a Rare Entity. Cureus, 17(10), 3–7. https://doi.org/10.7759/cureus.94731
Mookherjee, A., Rayudu, D. K., Vidyavathi, K., & Kundhan, H. (2024). Congenital mesenteric cysts : rare but important entities in abdominal surgery. International Surgery Journal, 11(2), 296–299.
Nicolae-dragos, M., Cercelaru, L., Vîlcea, I., & Barbu, A. (2025). Mesenteric Cysts as Rare Causes of Acute Abdominal Masses : Diagnostic Challenges and Surgical Insights from a Literature Review. Journal of Clinical Medicine, 1–15.
Shabana, A., Dholoo, F., Nunn, R., & Hameed, W. (2020). Case-report : A rare cause of an intra-abdominal mass. International Journal of Surgery Case Reports, 67, 278–281. https://doi.org/10.1016/j.ijscr.2020.01.006
Shewaye, A. B., Berhane, K. A., Gebresilassie, A. G., Fanta, A. D., Regassa, M., Ayalew, F., Fekede, E., & Ayalew, B. D. (2025). Case Report Giant Mesenteric Cyst in a Young Adult Mimicking Refractory Ascites : A Diagnostic and Surgical Challenge — A Case Report. Case Reports in Gastrointestinal Medicine, 2025.
Symeonidis, N. G., Pavlidis, E. T., Psarras, K. K., Stavrati, K., Nikolaidou, C., Marneri, A., Geropoulos, G., Meitanidou, M., Andreou, E., & Pavlidis, T. E. (2022). Preoperative Hyponatremia Indicates Complicated Acute Appendicitis. Surgery Research and Practice, 2022.
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