RADIOLOGY CORNER

Military Medicine, Feb 2007 by Ly, Justin Q, Sanders, Timothy G, Folio, Les

Answer to last month's radiology case and images: Schistosomiasis Japonicum Involving the Liver and Colon (Case # 10 appears at the end of this article)

Introduction: Colonic and hepatic calcifications are characteristic of Schistosomiasis infection of the gastrointestinal tract. Liver biopsy confirmed Schistosomiasis japonicum infection.

The full-text version is available in a downloadable PDF file on the AMSUS page of the USUHS website at: http://rad.usuhs.mil/amsus.html

History: A 51-year-old female with chronic left flank and pelvic pain. History of Schistosomiasis japonicum infection on previous liver biopsy. She reports prior travel to several Asian countries. On physical examination a nondistended abdomen and nonspecific lower abdominal pain was noted.

Summary of Findings: Abdominal radiography showed subtle curvilinear densities overlying the left lower quadrant and central within the pelvis (Fig. 1a). This was confirmed on intravenous contrastenhanced abdominopelvic CT to be caused by thin mucosal surface calcifications within the descending and sigmoid colons (Fig. 1b, c). Incidental note is made of thin right hepatic lobe capsule calcifications (Fig. 1d). These colonie and hepatic calcifications are characteristic of Schistosomiasis infection of the gastrointestinal tract. Liver biopsy confirmed Schistosomiasis japonicum infection.

Discussion: Schistosomiasis is a chronic infection caused by parasitic trematode worms that currently affects 200 million people in subtropical and tropical environments and is not an insignificant threat to deployed military members. (1) The main species of blood flukes or Schistosomes to infect humans are S. mansoni, S. japonicum, S. mekongi, and S. haematobium. The first three species characteristically affect the gastrointestinal tract (inhabiting the portal veins) and the latter typically affects the urinary tract (inhabit veins of bladder) and is the most common cause of bladder calcification in the world.

Imaging can play a role in demonstrating the extent of organ involvement and complications of Schistosomiasis infection. Conventional radiography may be the initial means of detecting calcification of the bladder or distal ureters (parallel linear radiodense appearance). CT is more sensitive than plain radiography for the detection and characterization of urolithiasis and pyelonephritis. The most reliable diagnostic techniques for detecting chronic bladder disease are cystoscopy, serology, CT, and to a lesser extent urography. Urinalysis in chronic disease may result in missed detection of disease that would otherwise be identified during the early phase of disease (2).

The primary treatment of schistosomiasis is the use of drug therapy, namely praziquantel, oxamniquine, and metrifonate. Early treatment can lead to rapid clinical improvement. Extensive fibrosis is associated with irreversible disease. Bleeding esophageal varices can be managed by sclerotherapy or surgery. Currently there is no vaccination; however, research is currently being conducted towards producing a safe and effective protective vaccine as a long-term solution to this significant health problem (3).

RADIOLOGY CORNER

CASE # 10

The answer to this case will appear in the next issue of Military Medicine

History: A 40-year-old man presented with right upper abdominal pain and fever. Physical examination was noncontributory. An upper abdominal ultrasound revealed a large, nonspecific cystic lesion of uncertain etiology, but lacked sonographic evidence of acute cholecystitis. Further evaluation with contrast-enhanced MR imaging was performed (Figs. 1a-c)

What is (are) the finding(s)? What is the differential diagnosis? Best diagnosis?

References:

1. Iarotski LS, Davis A. The schistosomiasis problem in the world: results of a WHO questionnaire survey. Bull World Health Organ. 1981;59:115-127.

2. Patil KP, Ibrahim AI, Shetty SD, el Tahir MI, Anandan N. Specific investigations in chronic urinary bilharziasis. Urology. 1992;40:117-9.

3. Pearce EJ. Progress towards a vaccine for schistosomiasis. Acta Trop. 2003;86:309-13.

Case provided by:

Capt Justin Q. Ly, MC, USAF '; Col Timothy G. Sanders, MC, USAF (Ret.)2; Col Les Folio, MC, SFS 2

1 Wilford Hall Medical Center

2 Uniformed Services University of the Health Sciences