Sonographic appearance of Mycobacterium pyometra mimicking carcinoma of uterine corpus

Abstract

Mycobacterium pyometra is extremely rare, and only 12 cases have so far been reported in the English literature (1–4). We report a case of Mycobacterium pyometra in an 84-year-old woman presenting with bloodstained vaginal discharge. Preoperative transvaginal ultrasound scan showed an intrauterine echogenic shadow, the appearance of which mimics carcinoma of uterine corpus. An 84-year-old woman was admitted because of bloodstained vaginal discharge. She suffered from diabetes, hypertension, dementia and stroke. There was no known history of pulmonary tuberculosis or tuberculosis infection of other organs. Pelvic examination revealed foul-smelling bloodstained discharge in the vagina. The uterus was of normal size and there was no adnexal mass. There was no tenderness. She was afebrile and her white cell count was 8.3 × 109/L. Transvaginal ultrasound scan showed fluid collection inside the uterine cavity and there was a 12.5 × 9.4 mm intrauterine echogenic shadow (Fig. 1). The provisional diagnosis was pyometra with suspected carcinoma of the uterine corpus. Transvaginal ultrasound image showing intrauterine fluid collection and an echogenic shadow. She underwent cervical dilatation under general anesthesia and a moderate amount of pus was drained upon dilatation. Hysteroscopy was performed using normal saline as the distending medium. The endometrium appeared inflamed but was smooth with no evidence of malignancy or other intrauterine growth. The cervical canal was normal. Uterine curettage was performed. She made a good recovery and was discharged two days after the procedure. Histological examination of the uterine curettage revealed endometrium with granulatomatous inflammation. There was no evidence of malignancy. Acid-fast bacilli were identified by Ziehl–Neelsen stain. Fungal stain was negative. A chest X-ray did not reveal any evidence of past tuberculosis infection. She was treated with a course of antituberculosis therapy that included isoniazid, rifampicin, ethambutol and pyrazinamide. Pyometra is an uncommon gynecologic condition that occurs mainly in postmenopausal women. The main risks of pyometra are its association with genital tract malignancy and spontaneous perforation of the uterus (5). The most common bacteria isolated are Escherichia coli and Bacteroides fragilis (6). Mycobacterium infection of the female genital tract mainly occurs in premenopausal women. Mycobacterium infection manifest as pyometra in postmenopausal women is extremely rare, with only 12 cases having been reported in the English literature so far (1–4). In the present case, the diagnosis of pyometra was made base on the clinical symptom of foul-smelling vaginal discharge and sonographic appearance of intrauterine fluid collection. In addition, there was an intrauterine echogenic shadow with features suggestive of endometrial carcinoma (7). The echogenic intrauterine shadow probably represented calcified tissue such as that seen in mycobacterium infection of the lung. The appropriate management of patients with suspected pyometra should comprise cervical dilatation to drain the pus, together with antibiotics. Assessment of the endometrial cavity should be deferred until the acute inflammation has subsided. Performing hysteroscopy in the presence of pyometra is potentially dangerous and should be contraindicated (8). This is because the infected material inside the uterine cavity may disseminate into the peritoneal cavity via the fallopian tube during hysteroscopy (9), resulting in peritonitis and septicemia. In addition, hysteroscopic examination of the endometrial cavity may be difficult in the presence of acute inflammation. The absence of complication in this patient may be related to the possible tubal blockage secondary to the mycobacterium infection, thus preventing the intraperitoneal spread of the infected materials. It is important to make the diagnosis of Mycobacterium pyometra so that antituberculous therapy can be given to cure the infection and to prevent recurrence and spread of disease to other organs. Mycobacterium infection is very prevalent in our community (10). There are also data to suggest that the incidence of mycobacterium infection of the genital tract in postmenopausal women is rising (11). Hence gynecologists may encounter more cases of Mycobacterium pyometra in the future. Although routine culture of uterine curettage with Lowenstein–Jensen medium in patients with pyometra is probably not justified, a careful histologic examination of the uterine curettage would be valuable and the presence of granulatomatous inflammation may suggest Mycobacterium pyometra. Clinicians and pathologists should be aware of this condition in order to avoid delay in diagnosis and appropriate therapy.