Isolated type I pelvic cystic echinococcosis mimicking ovarian tumor.

CONTEXT: Cystic echinococcosis is an endemic infestation with unique clinical and laboratory manifestations. Isolated pelvic type 1 cystic echinococcosis is a rare form of the disease with diagnostic pitfalls mainly based on non-diagnostic imaging findings. CASE REPORT: We present an isolated pelvic cystic echinococcosis resembling ovarian tumor which was diagnosed during operation.
CONCLUSIONS: Characteristic findings of hydatid disease lacks in type 1 and cause diagnostic difficulties. This rare entity should be considered for differential diagnosis due to varied examination findings especially in type 1 cystic echinococcosis.

Introduction

Cystic echinococcosis (CE) is an endemic infestation mainly affecting liver and lungs in accidental dead-end host –humans-. Clinical features of the CE infestation vary widely depending on the localization, size and the presence/absence of localized and systemic complications. Ultrasonography and magnetic resonance imaging are well-established diagnostic tools in CE. We present herein, a peculiar isolated pelvic CE case resembling an ovarian tumor.

Case report

A 66-year-old woman presented with pelvic pain and difficulty in urination. Pelvic examination revealed a palpable mass of nearly 8 Cm in diameter beneath posterior vaginal wall and uterus which obliterates vagina. Laboratory tests revealed elevated serum glucose (267 mg/dl), urea (59 mg/dl, normal range: 10-50) and creatinine levels (2.02 mg/dl, normal range: 0.20-1.20). Serum tumor markers were in normal range (CA 125: 6.88 U/L, CA 15-3: 9.49 U/L, CA 19-9: 14.88 U/L). Serum hemoglobin level was also decreased (9.65 mg/dl). She had past history of diabetes and hypertension.

Transvaginal ultrasound examination revealed anechoic cystic mass in the adnexial region (Figure 1). Cyst was visualized as having regular borders without any septum formation. Additionally, grade 3 dilatation of both renal pelvises were detected. Magnetic resonance imaging was reported as an ovarian malign mass with 13 and 9 cm of two dimensions, dilated bilateral renal pelvises and no other site of cystic mass involvement (Figure 2). Double J catheter could not be inserted to the both ureters. Bilateral percutaneous nefrostomy catheter only could be inserted to the right side due to incompatibility of the patient. Gradual increase in serum urea and creatinine levels was continued up to 189 and 3.25 mg/dl respectively before the operation.

Fig. 1

Ultrasound image showing unilocular cystic mass in adnexial region with anechoic content.

Fig. 2

Coronal (A) and Axial fat sat (B) T2 weighed magnetic resonance images of hypointense cystic mass. Proximity to the uterus and bladder is noticed (arrows).

Surgery with the presumptive diagnosis of ovarian tumor revealed a mass nearly in 10 Cm diameter located beneath the uterus towards Douglas pouch. During dissection of this mass serous material spilled (Figure 3). Hydatid cyst diagnosed after rupture of the cyst and visualization of the laminated membrane during operation. Cyst material carefully aspirated and neighboring sites were irrigated with povidone-iodine solution to prevent peritoneal spread.

Fig. 3

Intraoperative view of laminated membrane and postoperative specimens.

Postoperatively serum urea and creatinine returned to normal levels. Pathology result had confirmed the diagnosis. No other sites of involvement including thorax and liver were detected. She was prescribed albendazole 400 mg twice daily for 4 weeks to prevent metastatic cyst formation.

Discussion

Isolated pelvic CE is an unusual presentation affecting 0.2-0.9% of CE[1] and nearly 25 cases have been reported[2-5] previously. Cystic masses might be huge in size –as was depicted in our report- since CE usually has no specific symptoms for long periods in the absence of localized or systemic complications. When it becomes symptomatic, acute pain may refer to rupture or secondary infection. Otherwise, a dull ache may be the only symptom for years. Beyond the general clinical features, mass effect of CE in specific locations may determine the CE associated clinical course. Our case was a noteworthy one as obstructive nephropathy with gradually worsening renal function were leading clinical features.

Initial and widely used ultrasonographic classification of CE was proposed by Gharbi et al. in 1981[6]. This classification categorizes CE into five types from simple cystic appearance to the calcified form. WHO had modified this classification in 2003 and gathered these five groups in three groups as active, transitional and inactive and substituted type 2 and 3[7]. Both Gharbi’s Type I CE and WHO Type CE1 designate as unilocular cystic lesion with anechoic content. Along with change of CE type from 1 to 5, some distinctive features might appear such as multi-vesicular and multi-septated cystic appearance, wheel-like structures, rosette-like or honeycomb-like structures, detachment of the laminated membrane, water-lily sign and calcifications[7]. Non-complicated type 1 CE has diagnostic pitfalls as the diagnostics pearls of advanced CE are not encountered in type 1 CE and alternative diagnoses might be established based on the clinical features, non-diagnostic ultrasound and MRI findings as was in our case.

It is known that CE is inactive in type 4 and 5. This classification also describes grades of this disease. However, advancing grade-type is not correlated with prognosis. In each type, size of the cyst may vary and probably elevation of the size may be the most important factor for prognosis.

Differential diagnosis of type 1 cyst from ovarian cysts is difficult. Although CE has some characteristic signs, especially type 1 cysts may not involve them.

As a conclusion, type 1 CE should be kept in mind in the differential diagnosis of pelvic masses even with non-diagnostic imaging features in endemic regions.