# Confused Images Confused Eyes: A Case of Ultrasound Misdiagnosis of Pelvic Actinomycosis

## TL;DR

A case of pelvic actinomycosis was misdiagnosed as a tumor due to similar imaging features, but was correctly identified after biopsy and treated with penicillin.

## Contribution

Highlights the diagnostic challenges of pelvic actinomycosis and its similarity to ovarian malignancies.

## Key findings

- Pelvic actinomycosis was initially misdiagnosed as an ovarian tumor based on imaging.
- Biopsy confirmed the presence of Actinomyces infection with sulfur granules.
- Treatment with penicillin and IUD removal led to significant improvement.

## Abstract

This article introduces a case of pelvic actinomycosis, which is easily confused with an ovarian malignant tumor. These images are from a 52-year-old woman who was admitted to hospital with difficulty defecating. Colonoscopy and biopsy indicated inflammatory changes within the intestinal tract, but the anti-inflammatory treatment was not effective. Later, she was readmitted due to abdominal pain and emaciation, and laboratory findings revealed mild anemia and inflammation. Various tumor markers are normal. CT suggested inflammatory lesions in the sigmoid colon and upper rectum. PET-CT considered a high metabolic mass originating from the mesentery. Ultrasound scan revealed a mixed-echo mass adjacent to the right side of the uterus, poorly demarcated from the rectum and right ovary, suggesting a neoplastic lesion. A biopsy of the right ovarian mass indicated suppurative inflammation, with negative antacid staining and microscopic observation of yellowish sulfur granules, suggestive of Actinomyces infection. Following a 12-month treatment regimen involving the removal of an intrauterine device and administration of penicillin, the patient’s condition markedly improved. Pelvic actinomycosis is usually characterized by abdominal pain accompanied by an abdominal mass, which is often related to an intrauterine device (IUD), and is very difficult to distinguish from pelvic tumors and tuberculosis, so it is necessary for doctors to understand its clinical and imaging features.