Gallbladder carcinoma: causes of misdiagnosis at CT.

Gallbladder carcinomas can present with varied imaging features on computed tomography. The three major imaging features include (1) focal or diffuse wall thickening with or without irregularity of the gallbladder; (2) polypoidal intraluminal mass; and (3) large mass obscuring and replacing the gallbladder, often extending to the liver. Patterns of wall thickening or polypoid growth are often confused with various benign gallbladder diseases due to overlap of imaging findings. Moreover, gallbladder carcinomas that coexist with benign gallbladder diseases make accurate preoperative diagnosis more difficult. Recently, high-resolution ultrasound (HRUS) has been regarded as a problem-solving tool for gallbladder diseases. In this article, we will illustrate various imaging presentations of gallbladder cancer, along with imaging pitfalls and recently updated HRUS findings.

Gastrointestinal stromal tumours (GISTs) with a thousand faces: atypical manifestations and causes of misdiagnosis on imaging.

Gastrointestinal stromal tumours (GISTs) can lead to emergency situations, such as gastrointestinal bleeding, intestinal obstruction, and tumoural rupture with haemoperitoneum or peritonitis. In addition, if a GIST grows exophytically to a large size, it is often misdiagnosed as a tumour arising from adjacent organs. Sometimes, the atypical appearance of GISTs on imaging causes diagnostic confusion. In this article, we illustrate a variety of GISTs with atypical presentations and also discuss the important diagnostic clues for differentiating GISTs from other lesions.

Outbreak of cyclosporiasis associated with basil in Missouri in 1999.

During the summer of 1999, an outbreak of cyclosporiasis occurred among attendees of 2 events held on 24 July in different counties in Missouri. We conducted retrospective cohort studies of the 2 clusters of cases, which comprised 62 case patients. The chicken pasta salad served at one event (relative risk [RR], 4.25; 95% confidence interval [CI], 1.80-10.01) and the tomato basil salad served at the other event (RR, 2.95; 95% CI, 1.72-5.07) were most strongly associated with illness. The most likely vehicle of infection was fresh basil, which was included in both salads and could have been grown either in Mexico or the United States. Leftover chicken pasta salad was found to be positive for Cyclospora DNA by means of polymerase chain reaction analysis, and 1 sporulated Cyclospora oocyst was found by use of microscopy. This is the second documented outbreak of cyclosporiasis in the United States linked to fresh basil and the first US outbreak for which Cyclospora has been detected in an epidemiologically implicated food item.

A survey for Cyclospora spp. in Kenyan primates, with some notes on its biology.

From March 1999 through August 2000, 511 stool samples collected from 11 different primate species in 10 geographically distinct locations in Kenya, East Africa, were screened for the presence of Cyclospora spp. oocysts. Positive samples (43/102, 42%) were identified in vervet monkeys (Cercopithecus aethiops) in 4 of 4 locations; 19/206 (9%) in yellow and olive baboons (Papio cynocephalus, P. anubis, respectively) in 5 of 5 locations; and 19/76 (25%) in black and white colobus monkeys (Colobus angolensis, C. guereza, respectively) from 2 of 3 locations. DNA sequences obtained from 18 S rRNA coding regions from respective subsets of these positive samples were typed as Cyclospora cercopitheci (samples from Cercopithecus aethiops). Cyclospora papionis (samples from Papio cynocephalus and P. anubis), and Cyclospora colobi (samples from Colobus angolensis and C. guereza). Cyclospora oocysts were not detected in samples collected from patas, highland sykes, lowland sykes, blue sykes, DeBrazza, or red-tailed monkeys. A coded map showing the geographic location of the collected samples is given. Stool samples from 1 troop of vervet monkeys were collected over a 12-mo period. Positive samples ranged between 21 and 63%. These results suggest that there is no strongly marked seasonality evident in Cyclospora infection in monkeys as has been noted in human infection. This is further confirmed by the recovery of positive samples collected from vervet monkeys, baboons, and colobus monkeys at all times of the year during this survey. This absence of seasonality in infection is especially notable because of the extreme weather patterns typical of Kenya, where marked rainy and dry seasons occur. A second noteworthy observation is that the striking host specificity of the Cyclospora species initially described was confirmed in this survey. Baboons were only infected with C. papionis, vervet monkeys with C. cercopitheci, and colobus monkeys with C. colobi, despite geographic overlaps of both the monkey and parasite species and wide geographic distribution of each parasite and monkey host.

Attempts to establish experimental Cyclospora cayetanensis infection in laboratory animals.

Attempts were made to develop an animal model for Cyclospora cayetanensis to identify a practical laboratory host for studying human cyclosporiasis. Oocysts collected from stool of infected humans in the United States, Haiti, Guatemala, Peru, and Nepal were held in potassium dichromate solution to allow development of sporozoites. The following animal types were inoculated: 9 strains of mice, including adult and neonatal immunocompetent and immune-deficient inbred and outbred strains, rats, sandrats, chickens, ducks, rabbits, jirds, hamsters, ferrets, pigs, dogs, owl monkeys, rhesus monkeys, and cynomolgus monkeys. Most animals were inoculated by gavage, although some of the primates were fed oocysts on food items. The animals were examined for signs of infection, particularly diarrhea, and stool samples were examined for 4-6 wk after inoculation. None of the animals developed patent infections or signs of infection. We conclude that none of the animals tested is susceptible to infection with C. cayetanensis.