Fibrolamellar hepatocellular carcinoma: MR appearance mimicking focal nodular hyperplasia.

We report the MR findings of a case of fibrolamellar hepatocellular carcinoma that fulfilled MR criteria proposed as diagnostic of focal nodular hyperplasia. Because confusion of fibrolamellar carcinoma with focal nodular hyperplasia could result in a missed opportunity for cure, pathologic assessment remains necessary in cases demonstrating these MR findings that do not show radiotracer uptake on 99mTc-sulfur colloid scintigraphy.

Cavernous hemangioma of the adrenal gland: MR findings.

Adrenal hemangioma is considered a rare tumor and is pathologically similar to hemangiomas found elsewhere in the body. Magnetic resonance imaging (MRI) findings thought to be highly suggestive of this neoplasm are presented. Correlation with pathologic findings in this case, as well as imaging and pathologic findings in other reported cases, is provided.

Crystalloid structures in retroperitoneal paragangliomas: a light and electron microscopic study.

Samples from three clinically functional retroperitoneal paragangliomas were studied by light and electron microscopy. The tumors exhibited a Zellballen pattern histologically, and ultrastructurally all three neoplasms consisted of cells containing catecholamine granules. Prominent cytoplasmic crystalloids were present in all cases. The crystalloids were identified in routine histologic sections, demonstrated eosinophilia, and stained with periodic acid-Schiff, Giemsa, phloxine-tartrazine, and azan stains. Ultrastructurally the crystalloids were osmiophilic, often appeared as slender needles, were membrane bound, and demonstrated a periodicity of 9 nm. The crystalloids, unlike the catecholamine granules, were negative for catecholamine fluorescence. X-ray microanalysis, however, revealed the selective presence of chromium in both catecholamine granules and crystalloids.

Unusual skin tumors in Langerhans' cell histiocytosis.

A case of Langerhans' cell histiocytosis with unusual skin manifestations in the form of multiple large skin tumors is described. The skin lesions responded partially to chemotherapy with etoposide and prednisone, and residual lesions were excised surgically. The patient developed central diabetes insipidus during treatment.

Clinicopathological features of childhood nephrotic syndrome in Saudi Arabia.

The clinicopathological features are described in 119 Arab children in Saudi Arabia with the nephrotic syndrome. The clinical and laboratory data are similar to those described in other parts of the world. However, mesangial proliferative glomerulonephritis (MesPGN) was found in 21 of 66 biopsies (31.8%), giving a frequency of 17.6% of all children with the nephrotic syndrome. Minimal-change nephrotic syndrome (MCNS) was diagnosed in 17 biopsies (25.8%) and in 58 patients (48.7%). Onset of the nephrotic syndrome was at less than 1 year of age in 17 patients (14.3%). Seven children had 11 episodes of peritonitis. Seven children had positive hepatitis B surface antigen (HBsAg) in their serum: renal biopsy carried out on four of them showed membranous glomerulonephritis (MGN) in three, and four of the seven patients developed end-stage renal disease (ESRD). There were nine deaths, all in patients with end-stage renal disease: six of the deaths occurred in infants. The pattern of childhood nephrotic syndrome in Saudi Arabia is different from the pattern in tropical countries.

Nephrotic syndrome in Saudi infants in the first year of life.

Sixteen Saudi children with onset of nephrotic syndrome in infancy were seen at King Khalid University Hospital, Riyadh over a 5-year period. This figure represented 17% of the 92 cases of childhood nephrotic syndrome seen during the period. Onset of the nephrotic syndrome was less than or equal to 3 months of age in four patients. Ten of the patients developed renal failure. Eight patients died, seven of them by 1 year of age. Two patients given renal transplants have functioning grafts without recurrence of the disease. Renal biopsy in 12 patients showed congenital nephrotic syndrome of the Finnish type (4 cases), 2 each of congenital glomerulosclerosis, mesangioproliferative glomerulonephritis and minimal change disease, and 1 each of focal segmental glomerulosclerosis and tubular amyloidosis. Prognosis of infancy-onset nephrotic syndrome in Saudi children was poor. A significant prognostic factor appeared to be the age of onset of the disease rather than the histological lesion.

Roentgenology-pathology correlative study of neovascularity.

In an attempt to evaluate the histologic picture of what is shown on angiograms as neovascularity, several benign and malignant tumors were examined. New vessels (neovascularity) are large capillaries or sinusoids, and neither contain smooth muscle in their walls. The walls may contain some fibrous connective tissue. Puddling, laking, and staining represent the collection of contrast medium in small capillaries or sinusoids. Some tumors, such as hemangioma of the liver, cystadenoma of the pancreas, and angiomyolipoma of the kidney contained abnormal vascularity, but this was not composed of vessels which had arisen or developed anew, as there was smooth muscle in their walls, and this indicates that those vessels had been there from birth. In xanthogranulomatous pyelonephritis and chronic renal disease, the appearance of increased vascularity is the result of rearrangement of the normal vascular structures.

Semliki Forest virus in HEp-2 cell cultures.

The growth and development of Semliki Forest virus (SFV), an arbovirus of serological group A, in HEp-2 cells in tissue culture was examined by various techniques at frequent intervals. Infectivity and fluorescent-antibody studies demonstrated the presence of infective virus and viral antigens within the cells at 8 hr after infection. The antigen was particulate and distributed throughout the cytoplasm. Thereafter, there was rapid progression of virus production and cell destruction. By electron microscopy, tubular structures bounded by a fine membrane were observed in cytoplasm at 12 hr. Rows of small (25 mmu) virus particles were often present on the outer surface of these membranes, and at later times they became progressively more encrusted with the small virus particles. These structures subsequently increased rapidly in number, size, and complexity, and the space between the membrane and the tubules increased, thus forming vacuoles which contained tubules and were covered with the small particles. At later times (24 hr and later) larger (42 to 50 mmu) particles were observed, usually inside of the vacuoles. These larger particles (and occasionally the smaller ones) were also seen at the cell periphery and in the extracellular space. The large SFV particles appear to form by three distinct processes: (i) from the smaller particles, (ii) by development on an intravacuolar membrane, and (iii) at the ends of the tubules. The mode of development of SFV is unique among viruses studied to date, but in some characteristics it resembles that of other group A arboviruses. Its development differs from that of most arboviruses of group B and other serological groups.