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Hepatosplenomegaly in a "Lost Boy of Sudan".

A 21-year-old Sudanese man presented to the emergency department after 2 days of fever, nausea, vomiting, and mild bloody diarrhea. Clinical findings included hepatosplenomegaly and abdominal distension. Past medical history included hepatitis B infection and prior infection with a "worm." The patient had moved to the USA 6 weeks prior to his admission. Laboratory findings revealed a decreased white blood cell count of 4100/[micro]L (reference range, 4500-11,000) with peripheral eosinophilia: the white cell differential included 43% eosinophils (reference range, 0%-5%), and the absolute eosinophil count was 2370/[micro]L (reference range, 0-550). Abdominal imaging studies (ultrasonography, computed tomography [CT], and magnetic resonance imaging [MRI]) all demonstrated hepatosplenomegaly. Given the patient's clinical history of hepatitis B, this finding was attributed to chronic hepatitis. In addition, the abdominal sonogram demonstrated nonspecific periportal increased echogenicity. Abdominal CT showed periportal edema and/or fibrosis. Abdominal MRI demonstrated periportal edema on T1- and T2-weighted images with periportal enhancement after the intravenous administration of gadolinium contrast agent (Figures 1 and 2).

[FIGURES 1-2 OMITTED]

What is the most likely diagnosis?

DIAGNOSIS: Hepatic schistosomiasis from infection with Schistosoma mansoni.

Ultrasound-guided core needle biopsy of the liver revealed degenerating parasitic organisms associated with hepatocellular fibrosis, granulomatous infection, and eosinophilia (Figure 3). In addition, an enzyme-linked immunosorbent assay demonstrated an elevated Schistosoma IgG antibody value of 6.42 (<1.00, antibody not detected; =1.00, antibody detected).

[FIGURE 3 OMITTED]

DISCUSSION

Schistosomiasis is a parasitic infection caused by digenetic blood trematodes, or flatworms, of the genus Schistosoma. Five species cause schistosomiasis: S. mansoni, S. japonicum, S. mekongi, S. haematobium, and S. intercalatum. Most cases of hepatosplenic schistosomiasis are caused by S. mansoni and S. japonicum.

In tropical regions, the public health and socioeconomic impact of schistosomiasis, or snail fever, is staggering: only malaria is a more devastating parasitic disease. Estimates are that 200 million people are infected with schistosomiasis worldwide, half of them in Africa alone (1). The disease is prevalent in many developing countries in Africa and South America, and in the Mediterranean, Caribbean, and Pacific regions. Each species tends to be endemic to a particular region.

Our patient was a refugee from war-torn Sudan, a large country in northeast Africa bordering the Red Sea. Sudan is located at a crossroads between the Horn of Africa and the Middle East. In Khartoum, the capital, the Blue and White Nile rivers meet to form the Nile River, which flows northward through Egypt to the Mediterranean Sea. Throughout Sudan, irrigation from the Nile rivers has led to widespread habitat for the snails that are essential to the seasonal life cycle of S. mansoni (2). Despite various strategies to control the snail population in the endemic areas, schistosomiasis remains prevalent (3).

Life cycle

The life cycle of S. mansoni is very complex (Figure 4). Feces from infected individuals contaminate the local water with eggs, and the eggs release motile miracidia that in turn infect freshwater snails. Within the snail, the miracidium transforms into a sporocyst, which divides and eventually produces thousands of cercariae. The snail excretes the cercariae into the surrounding water. These larvae then penetrate human skin via proteolytic enzymes. Once through the skin, the cercariae shed their forked tails and become schistosomulae, which then migrate through the peripheral vasculature, ultimately ending up in the mesenteric and portal venous system (4). Here, they develop into adult worms. Females produce many hundreds of eggs per day. The body's reaction to the worms and their eggs causes the pathologic changes that produce clinical hepatosplenic schistosomiasis.

[FIGURE 4 OMITTED]

Pathogenesis

Schistosomes are hepatotoxic in several ways. The eggs of S. mansoni release substances that are directly hepatotoxic. Carbohydrate antigens from the eggs induce macrophage accumulation and granuloma formation mediated by tumor necrosis factor and helper T cells. The helper T cells go on to cause eosinophilia, mastocytosis, and high levels of IgE in response to the release of multiple interleukins. The eggs also release a fibrinogenic lymphokine that causes fibroblast proliferation and portal fibrosis (5). This fibrosis is disproportionate to the hepatic injury caused by the eggs and granulomas (6).

Symptoms

Many people who have been infected are subclinically symptomatic with mild anemia and malnutrition. Acute schistosomiasis can occur weeks after the initial infection. Clinical manifestations include fever, abdominal pain, diarrhea, cough, fatigue, and hepatosplenomegaly. Portal hypertension is a late manifestation related to chronic periportal fibrosis. A field study from Sudan revealed a crude schistosomiasis mortality rate of 51 per 100,000 per year. The overall schistosomiasis fatality rate per year among infected persons was 0.1% but was as high as 11% among infected patients with bleeding varices related to portal hypertension (7).

Imaging findings

Typical imaging findings are nonspecific and usually occur years after the initial infection. On ultrasound, the liver surface contour is irregular and the liver parenchyma has a "mosaic" appearance, manifest by echogenic septa outlining areas of relatively normal liver that vary in size. The main findings are periportal fibrosis, left lobe hypertrophy, thickening of the gallbladder wall, granulomas, splenic nodules, and widening of the portal vessel system (8). Less common ultrasound findings include a mottled, nodular appearance representing septal fibrosis with or without calcifications.

Findings on CT include the presence of calcified fibrous septa, which are usually perpendicular to the liver capsule and give a typical "tortoiseshell" appearance. These fibrous septa and the liver capsule may demonstrate enhancement with intravenous contrast. There may also be an irregular hepatic surface contour with extension of the pericholecystic fat into the liver secondary to fibrosis and hepatic parenchymal retraction (9).

On MRI, hepatosplenic alterations in schistosomiasis are characterized by heterogeneity of the hepatic parenchyma and the presence of peripheral perihepatic vessels, periportal fibrosis, splenomegaly, siderotic nodules, and venous collateral pathways (10).

Imaging findings more specific for chronic infection with S. mansoni include wall thickening of the portal vein and its branches secondary to fibrosis. On ultrasound, this gives a "bulls-eye" appearance, which refers to the anechoic portal vein surrounded by echogenic fibrous tissue. On CT, periportal fibrosis appears as areas of decreased attenuation surrounding the portal venous branches, which enhance after administration of intravenous contrast. On MRI, the periportal regions are isointense to liver on T1 and hyperintense on T2. They avidly enhance after administration of gadolinium. Enlargement of the left hepatic lobe, splenomegaly, and the presence of portosystemic venous collaterals are also common.

In our patient, abdominal ultrasound demonstrated splenomegaly, periportal increased echogenicity, gallbladder wall thickening, and a heterogenous coarsened echotexture of the liver. Some areas of the liver parenchyma were very echogenic while others were hypoechoic, suggesting a diffuse hepatocellular abnormality (Figure 5).

[FIGURE 5 OMITTED]

Contrast-enhanced CT demonstrated diffuse heterogeneous appearance of the liver with periportal edema (Figure 6). There were multiple sequelae of portal hypertension, including splenomegaly, esophageal varices, and a recannulated paraumbilical vein. Gallbladder wall thickening was present with inflammatory stranding within the pericholecystic fat.

[FIGURE 6 OMITTED]

Abdominal MRI demonstrated marked hepatosplenomegaly with extensive periportal edema and contrast enhancement after the intravenous administration of gadolinium. Images of the gallbladder showed wall thickening, pericholecystic edema, and portosystemic collateral venous pathways.

Treatment

The mainstay of treatment is praziquantel; a single annual dose costing 18 cents can prevent schistosomiasis and control transmission. For ease of treatment in endemic countries such as Sudan, the World Health Organization distributes a wall-mounted measuring chart that recommends doses of praziquantel based on the height of the patient (11). The Centers for Disease Control and Prevention even recommends a therapeutic regimen for presumptive treatment of schistosomiasis in refugees arriving in the USA from Sudan (12).

Acknowledgment

The authors thank Maria R. Lepe-Suastegui, MD, for providing the photomicrograph, which was taken by David Watkins, MD.

(1.) The Carter Center. Schistosomiasis control overview: the Carter Center schistosomiasis control program. Available at http://www.cartercenter. org/health/schistosomiasis/index.html; accessed April 23, 2007.

(2.) Hilali AH, Madsen H, Daffalla AA, Wassila M, Christensen NO. Infection and transmission pattern of Schistosoma mansoni in the Managil irrigation scheme, Sudan. Ann Trop Med Parasitol 1995;89(3):279-286.

(3.) Babiker A, Fenwick A, Daffalla AA, Amin MA. Focality and seasonality of Schistosoma mansoni transmission in the Gezira Irrigated Area, Sudan. J Trop Med Hyg 1985;88(2):57-63.

(4.) Centers for Disease Control and Prevention. Schistosomiasis. Available at http://www.dpd.cdc.gov/dpdx/html/Schistosomiasis.htm; accessed April 23, 2007.

(5.) Samuelson J. Infectious diseases. In Cotran RS, Kumar V, Collins T, eds. Robbins Pathologic Basis of Disease, 6th ed. Philadelphia: WB Saunders, 1999:396-397.

(6.) Mortele KJ, Segatto E, Ros PR. The infected liver: radiologic-pathologic correlation. Radiographics 2004;24(4):937-955.

(7.) Kheir MM, Eltoum IA, Saad AM, Ali MM, Baraka OZ, Homeida MM. Mortality due to schistosomiasis mansoni: a field study in Sudan. Am J Trop Med Hyg 1999;60(2):307-310.

(8.) Cerri GG, Alves VA, Magalhaes A. Hepatosplenic schistosomiasis mansoni: ultrasound manifestations. Radiology 1984;153(3):777-780.

(9.) Monzawa S, Uchiyama G, Ohtomo K, Araki T. Schistosomiasis japonica of the liver: contrast-enhanced CT findings in 113 patients. AJR Am J Roentgenol 1993;161(2):323-327.

(10.) Bezerra AS, D'Ippolito G, Caldana RP, Cecin AO, Ahmed M, Szejnfeld J. Chronic hepatosplenic schistosomiasis mansoni: magnetic resonance imaging and magnetic resonance angiography findings. Acta Radiol 2007;48(2):125-134.

(11.) World Health Organization. [Wall charts for distribution of praziquantel and ivermectin.] Available at http://whqlibdoc.who.int/publications/ 2006/9241547103_annexes_eng.pdf; accessed April 23, 2007.

(12.) Centers for Disease Control and Prevention. Updated: recommendations for presumptive treatment of schistosomiasis and strongyloidiasis among the Lost Boys and Girls of Sudan (released June 13, 2005). Available at http://www.cdc.gov/ncidod/dq/refugee/lostboysandgirlssudan/updated_ presumptive_tx_recc_061305.htm; accessed April 23, 2007.

Scott C. Adams, MD, and William G. Schucany, MD

From the Department of Radiology, Baylor University Medical Center, Dallas, Texas.

Corresponding author: William G. Schucany, MD, Department of Radiology, Baylor University Medical Center, 3500 Gaston Avenue, Dallas, Texas 75246 (e-mail: gschucany@americanrad.com).
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Title Annotation:Radiology Report
Author:Adams, Scott C.; Schucany, William G.
Publication:Baylor University Medical Center Proceedings
Geographic Code:1USA
Date:Jul 1, 2007
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