Differential Diagnosis for Pelvic Masses

The clinical presentation of two large cystic masses in the pelvis, with one identified as the urinary bladder and the other being a separate cystic mass measuring 20 cm, extending into the anterior abdomen, along with moderate hydronephrosis and hydroureter on the right, suggests several potential diagnoses. These can be categorized as follows:

• Single Most Likely Diagnosis

  • Urinary Bladder and Ovarian Cyst: Given the presence of a large cystic mass separate from the urinary bladder, an ovarian cyst is a plausible diagnosis. Ovarian cysts can grow to significant sizes and can cause compression effects on surrounding structures, leading to hydronephrosis and hydroureter if they obstruct the ureters.

• Other Likely Diagnoses

  • Urinary Bladder and Ureteral Diverticulum or Cyst: Although less common, a large ureteral diverticulum or a cyst related to the ureter could present similarly, especially if it causes obstruction leading to hydronephrosis.
  • Urinary Bladder and Pelvic Lymphocele: A lymphocele, which is a collection of lymphatic fluid, can form in the pelvis after surgery or due to other causes and could be considered in the differential diagnosis if there's a relevant history.
  • Urinary Bladder and Abscess or Hematoma: In the context of infection or recent trauma/surgery, a large abscess or hematoma could present as a cystic mass in the pelvis.

• Do Not Miss Diagnoses

  • Malignant Tumors (e.g., Ovarian, Bladder, or Ureteral Cancer): It's crucial not to miss a malignant process, as these can present with large masses and obstructive symptoms. Early diagnosis significantly impacts treatment and prognosis.
  • Ruptured or Infected Cyst: A ruptured or infected cyst can lead to severe consequences, including peritonitis or sepsis, and thus, prompt diagnosis and intervention are critical.

• Rare Diagnoses

  • Mesenteric or Omental Cyst: These are rare, benign cysts that can occur in the abdomen and pelvis, arising from the mesentery or omentum.
  • Müllerian Duct Cyst: A congenital anomaly that can result in a cystic structure in the pelvis, which may be discovered incidentally or due to symptoms from compression of adjacent structures.
  • Urachal Cyst: A cyst that forms from the remnants of the urachus, which is the embryonic connection between the bladder and the allantois. It can present as a midline abdominal mass and may be connected to the bladder.