Paraganglioma of the temporal bone: role of magnetic resonance imaging versus computed tomography.

Paragangliomas, also known as glomus tumors or chemodectomas, are tumors arising from chemoreceptor tissue (paraganglia), which are neural crest in origin and found in higher concentration along the glossopharyngeal and vagal cranial nerve. Three types of paragangliomas are related with the temporal bone: glomus tympanicum, glomus jugulare, and glomus vagale. The role of computed tomography (CT) and magnetic resonance imaging (MRI) in diagnosing these types of tumors is discussed, along with the importance of arteriography in aiding the diagnosis and treatment. This article discusses the choice between CT and MR based on clinical symptoms and tumor location, and illustrates the newest CT, MR, and angiography applications. A brief discussion on treatment options is given.

The diagnostic value of electron microscopy in human immunodeficiency virus-positive patients with gastrointestinal disease.

BACKGROUND: Our aim was to determine the diagnostic value of electron microscopy in evaluating the etiology of gastrointestinal disease in patients infected with the human immunodeficiency virus (HIV). METHODS: A retrospective review of electron microscopic and light microscopic results of all HIV-positive patients with gastrointestinal and liver diseases was made during a 3-year period from June 1995 to June 1998. RESULTS: A total of 145 HIV-positive patients had their electron microscopy specimens reviewed. Of these, 136 were investigated for diarrhea, and the other 9 for increased liver enzymes. Twenty-seven of the 145 (18.6%) HIV-positive patients had a pathogen identified by electron microscopy, compared with only 13 of 145 (9%) identified by light microscopy (P < 0.005). The sensitivity of light microscopy for detecting opportunistic pathogens was 68%. Twenty-one of the 27 (77.8%) patients diagnosed by electron microscopy had microsporidiosis, and the most commonly diagnosed species was Enterocytozoon bieneusi. Light microscopy failed to identify 12 cases of microsporidiosis and 2 cases of leishmaniasis. CONCLUSIONS: Electron microscopy contributes substantially to the identification of pathogens in HIV-positive patients. Light microscopy failed to identify one of every two pathogens diagnosed by electron microscopy.

Acute cholecystitis in AIDS patients: correlation of Tc-99m hepatobiliary scintigraphy with histopathologic laboratory findings and CD4 counts.

BACKGROUND: AIDS patients are susceptible to opportunistic gastrointestinal infections including ascending cholangitis and cholecystitis, especially if CD4 count is < 200. Incidence of acalculous cholecystitis has not been reported previously. PURPOSE: We aim to evaluate the incidence of acalculous cholecystitis in AIDS patients and to identify causative organisms and mortality rate following cholecystectomy. MATERIALS AND METHODS: We reviewed the files of 46 patients in order to meet the objectives of this study. RESULTS: CD4 counts were < 200 in 31 patients and > 200 in 15 patients. HIDA imaging was performed in 31 patients; in 8, the CD4 count was > 200 and all had calculous cholecystitis. The gallbladder was visualized in 3 patients for a sensitivity of 63% and no organisms were found in the gallbladder specimens. In 23 patients, the CD4 count was < 200; the gallbladder was visualized in 5 patients for a HIDA sensitivity of 78%; 16 (52%) had acalculous cholecystitis; and 15 had calculous cholecystitis. In acalculous cholecystitis, Cryptosporidium was found in six cases, cytomegalovirus (CMV) in six cases, and fungus, yeast, tuberculosis, and mycobacterium avium intracellular each in one case. The thirty day mortality rate was 18%; 5 of 28 who underwent open cholecystectomy died within 30 days, 4 of them with a CD4 count < 200. There was no mortality in the 26 patients who underwent laparoscopic cholecystectomy. CONCLUSION AND RECOMMENDATIONS: (1) Because of the high incidence of 52% of acalculous cholecystitis in AIDS patients with a CD4 count < 200, we recommend using intravenous cholecystokinin if the gallbladder is visualized on hepatobiliary scintigraphy in order to determine gallbladder ejection fraction and exclude acalculous cholecystitis. (2) Laparoscopic rather than open cholecystectomy should be the surgical procedure of choice in AIDS patients especially if the CD4 count is < 200.

Lower Helicobacter pylori infection and peptic ulcer disease prevalence in patients with AIDS and suppressed CD4 counts.

OBJECTIVE: The prevalence of Helicobacter pylori (HP) has previously been reported to be lower in AIDS patients. This study evaluated the prevalence of HP and peptic ulcer disease in relation to absolute CD4 counts in HIV-seropositive patients with GI symptoms. DESIGN: Seventy-two patients (48 HIV-positive and 24 HIV-negative) with GI symptoms were evaluated with upper endoscopy and antral gastric biopsy. Samples were prepared with Giemsa stain and reviewed by a single pathologist to determine status of HP infection. The patients were stratified on the basis of HIV status and CD4 count: group A, HIV-positive patients with a CD4 count greater than 200, group B, HIV-positive patients with CD4 counts less than 200, and group C, an HIV-negative control group. RESULTS: The prevalence of HP infection in the three groups was as follows: group A 69% (11/16), group B 13% (4/32), and group C 63% (15/24). Peptic ulcer prevalence in group A was 19% (3/16), group B 3% (1/32), and group C 25% (6/24). CONCLUSIONS: The prevalence of HP in HIV-positive patients with a CD4 count less than 200 is significantly lower (p < 0.001) than that found in HIV-negative patients. The number of peptic ulcers in the HIV-positive group with CD4 < 200 was significantly less (p = 0.035) than that of the HIV-negative patients. These results suggest a role of CD4 cell and immune function in sustaining HP infection and HP-related peptic ulcer disease.

Imaging features of splenic epidermoid cyst with pathologic correlation.

The spleen can be involved in a variety of cystic lesions ranging from cystic neoplasms and parasitic cysts to "true" and "false" cysts. Epidermoid splenic cyst is a rare true cyst that is developmental in origin. We present two young patients with such a cyst and illustrate their features on ultrasound, CT, and MRI with pathologic correlation.

Management of suspected antenatal torsion: what is the best strategy?

Currently, management of the newborn with suspected antenatal torsion is somewhat controversial. Many surgeons recommend early surgical exploration within the first few days of life, primarily to avoid errors in diagnosis. However, since the surgical and general anesthetic risks at this age are increased, it might be preferable to defer an operation until risks to the patient are minimized. The optimal solution to this dilemma would be the ability to diagnose torsion and exclude other conditions noninvasively. We present a series of 12 patients 1 to 14 days old who presented with a scrotal mass secondary to suspected antenatal testis torsion. Color Doppler ultrasound in each case demonstrated abnormal testicular blood flow and architecture consistent with testis torsion. Eventual exploration of all 12 patients confirmed prenatal torsion. We conclude that scrotal ultrasound with color Doppler enhancement can accurately identify neonates with antenatal testis torsion and exclude other scrotal pathological conditions. If elected, surgery for torsion can then be deferred until the risks of anesthesia and surgery are improved.

Do all children with an acute scrotum require exploration?

A total of 77 consecutive children ranging in age from 1 day to 17 years was evaluated for an acute scrotum by a single examiner (E. J. K.). In 10 children a definite diagnosis of acute spermatic cord torsion was made based upon the history and physical examination. No imaging studies were performed and torsion was confirmed at surgery in 9 children. The diagnosis of testis torsion was not as clear-cut in the remaining 67 children and, therefore, a color Doppler ultrasound was performed before any surgical intervention. The study demonstrated normal or increased blood flow in 55 of these children and none proved to have testicular torsion, although other scrotal pathology requiring surgery was noted in 5 children. Twelve children did not demonstrate evidence of testicular blood flow on the color Doppler ultrasound and all had surgical confirmation of testis torsion. We conclude that in our experience the majority (71%) of children with an acute scrotum did not require immediate surgical exploration. Color Doppler ultrasound can reliably identify those children with an acute scrotum who require exploration and spare the majority needless surgery. Routine scrotal exploration is no longer necessary for all children with an acute scrotum.

Transient acute renal failure in the neonate.

We have observed a transient renal insufficiency in newborns associated with ultrasonographic finding of hyperechoic renal pyramids. This condition rapidly resolves, coinciding with both normalization of the renal ultrasound and the occurrence of significant proteinuria. Others have recognized a similar state of oliguria and cylindruria associated with a prolonged nephrogram on intravenous urography in newborns. There is evidence to suggest that hyaline cast deposition within the collecting tubules may account for these imaging abnormalities. The precise events surrounding the protein deposition are unknown, and it may be either the cause or the result from the transient renal dysfunction. Our 2 cases add to the evidence that there is a distinct entity of acute renal dysfunction, with identifying characteristics, in neonates associated with a good prognosis and rapid resolution.

Cholelithiasis in infants with Down syndrome. Three cases and literature review.

Only four cases of cholelithiasis have been reported in patients with Down syndrome and none in Down syndrome infants. The cases of three Down syndrome infants (all males) with cholelithiasis are reported. Each exhibited different fetal complications, and in each, Down syndrome was diagnosed at birth. Gallstones apparently were congenital (a rarity) in one infant, since they were detected on the first day of life. Cholelithiasis was an incidental finding in another of the infants when, at 12 weeks old, he had renal ultrasonography because of a urinary tract infection. The third infant was 4 months old when sonographic studies revealed a gallstone. Despite the confirmation of cholelithiasis in all three infants, none has since had any signs or symptoms that suggest the need for intervention. Cholelithiasis is probably more common in Down syndrome infants than has been supposed, but whether Down syndrome infants with gastrointestinal (GI) malformations are more likely to have gallstones than are children with similar GI malformations but with normal karyotypes is unknown.

Congenital malformations of the cervicothoracic lymphatic system: embryology and pathogenesis.

Familiarity with the embryology of the lymphatic system is helpful in understanding the pathogenesis and radiologic appearance of lymphangiomas of the cervicothoracic region. By considering anatomic location and radiologic appearance, one can predict the type of lymphangioma present, the primordial lymph sac from which the malformation arose, and when it formed in embryonic life. Cystic hygromas are composed of large, dilated lymphatic spaces. They form when a primordial lymph sac fails to reestablish communication with the central venous system from which it arose. These lesions may also result from an aberrant bud arising from a primordial lymph sac. Cavernous and capillary lymphangiomas are composed of smaller lymphatic channels. They form from abnormally sequestered buds of the developing lymphatic mesenchyme responsible for the fine meshwork of terminal branches in the periphery of the embryo. Their growth may be inhibited by the relatively tougher tissues in the periphery (eg, skin and muscle) compared with the relatively loose fatty connective tissue in which cystic hygromas form. Not only can all types of lymphangioma occur in one lesion, but lymphatic and vascular malformations may also coexist.

Congenital anomalies of the branchial apparatus: embryology and pathologic anatomy.

Various congenital anomalies of branchial origin are found in the neck region. Understanding the varied radiologic appearances of these anomalies is greatly aided by familiarity with their embryologic origins. By considering the anatomic location and radiologic appearance, the precise embryologic origin can be accurately predicted. Defects of the branchial apparatus include branchial, thymic, and parathyroid anomalies, which may manifest as cysts, sinuses, fistulas, and ectopic glands. The embryologic model is used to explain the origins of all branchial apparatus anomalies. The most accepted theory proposes that vestigial remnants result from incomplete obliteration of the branchial apparatus or buried cell rests, and, thus, if cells are trapped in the branchial apparatus during the embryologic stage, they can form branchial cysts later in life. By understanding the embryologic basis for these defects, the radiologist is better able to interpret the findings encountered with the various imaging modalities used in the evaluation of these anomalies.

The sensitivity of renal scintigraphy and sonography in detecting nonobstructive acute pyelonephritis.

Recently it has been demonstrated that any child with proved acute pyelonephritis may be at risk for parenchymal scarring, whether or not reflux is present. Since cortical renal scintigraphy has been shown to detect accurately renal inflammation, we compared cortical scintigraphy with renal sonography in 46 children with documented acute pyelonephritis to determine which modality is best to detect patients at risk for renal injury. Cortical scintigraphy was abnormal in 36 children (78%) and renal ultrasonography was abnormal in 5 (11%). Reflux was demonstrated in only 20 cases (43%). We conclude that cortical scintigraphy is the preferred imaging technique for diagnosing renal inflammation, and it should be used routinely in every child with suspected acute pyelonephritis. A new imaging protocol is proposed.

Clinical and imaging features of rhabdoid tumor of the kidney.

Rhabdoid tumor of the kidney (RTK) is a rare, highly malignant neoplasm of childhood. The clinical profile of this neoplasm differs from that of Wilms' tumor. We present two cases of RTK. In both our cases, large bulky masses with poorly defined margins and calcifications were demonstrated. The clinical and imaging findings are compared with other childhood renal neoplasms.

Urachal remnants: sonographic demonstration in children.

On 62 of 100 pediatric bladder sonograms a small, elliptical, hypoechoic structure was observed on the middle of the anterosuperior surface of the urinary bladder. One of the these structures was removed surgically, and pathologic examination disclosed a normal urachal remnant. Since it is a common sonographic finding in children, it should not be mistaken for a pathologic process unless it is accompanied by signs and symptoms of infection or bladder obstruction.