Haemophilus influenzae abscess: Inclusion in the Differential Diagnosis of a Large Pelvic Mass?

Background: This report describes an unusual first case in which an abscess containing Haemophilus influenzae incorporates the entire uterine cavity without overt signs of infection. Case: A 39-year-old woman presented with right lower quadrant abdominal pain and a large abdominal pelvic mass. Evaluation with computed tomography and ultrasonography showed a 20- × 14- × 10-cm cystic mass arising from the uterus. Tumor markers were negative. The patient underwent a total abdominal hysterectomy. Intraoperative findings included a 20-cm intramyometrial uterine abscess, completely replacing the uterine cavity. The abscess was densely adhered to the sigmoid colon. The mass was ruptured during the surgical procedure when mobilizing it off the colon, and cultures were obtained. Microbiologic culture illustrated H. influenzae. Pathologic diagnosis confirmed an intramyometrial abscess, originating from the wall of the uterus occupying the entire uterine cavity, lined with granulation tissue, foamy macrophages, and chronic inflammation. Conclusion: Intramyometrial abscesses can masquerade as degenerating fibroids and, even with microorganisms, can exist without overt signs or symptoms of an active infection.