Clinicopathologic features of nephrogenic rests and nephroblastomatosis.

Nephrogenic rests are the consequence of residual metanephric tissue in a fully developed kidney. They usually occur along the perimeter of a mature renal lobe (i.e., perilobar), within the lobe itself (i.e., intralobar), or both (i.e., combined). Nephrogenic rests can be grossly obvious or microscopically discrete. Nephroblastomatosis designates nephrogenic rests that are multifocal or diffuse, and implies more extensive disease. Universal (panlobar) nephroblastomatosis denotes complete replacement of the renal lobe by nephrogenic tissue. The fate of nephrogenic rests and nephroblastomatosis varies and includes obsolescence, sclerosis, dormancy, hyperplasia, or neoplasia. Evidence strongly suggests that neoplastic transformation of nephrogenic rests results in Wilms' tumor (nephroblastoma). Nephrogenic rests almost always occur in the setting of Wilms' tumor; perilobar rests show a strong association with synchronous bilateral Wilms' tumors, whereas intralobar rests are more strongly associated with metachronous tumors. Genetic studies have shown that nephrogenic rests often share many of the same chromosomal defects as Wilms' tumor, which provides further evidence that they are precursors to nephroblastoma. Thus, nephrogenic rests are recognized as clinically significant entities requiring adequate detection and close surveillance. Heightened awareness regarding the clinical relevance of nephrogenic rests and nephroblastomatosis (1) has led to improved detection of these precancerous lesions, (2) fostered more intensive investigation into their biologic behavior, and (3) initiated in-depth discussions about potentially new treatment regimens. The pathologists' ability to identify and detect nephrogenic rests has benefited from the more efficient Beckwith classification. Radiologists have deployed high-resolution radiologic/imaging modalities to improve detection of nephrogenic rests in situ. Clinicians and surgeons are more aware of the impact that nephrogenic rests have upon patient management. Despite this progress, more data is needed to further define these lesions.

Immunohistochemical detection of FLI-1 protein expression: a study of 132 round cell tumors with emphasis on CD99-positive mimics of Ewing's sarcoma/primitive neuroectodermal tumor.

The histologic and immunohistochemical differentiation of Ewing' s sarcoma/primitive neuroectodermal tumor (ES/PNET) from other small, blue, round cell tumors may be difficult. Despite initial promise, CD99 (MIC2) has not proven to be a specific marker. Approximately 90% of ES/PNET have a specific t(11; 22)(q24;q12) that results in fusion of the EWS and FLI-1 genes, and overexpression of FLI-1 protein. A recent study has shown immunohistochemical FLI-1 expression in five of seven of the ES/PNET cases tested. We evaluated FLI-1 expression in 132 well-characterized small, blue, round cell tumors. All tumors were immunostained for FLI-1 (1:40, Sc 356 polyclonal, Santa Cruz Biotechnology) using steam heat for epitope retrieval. Only nuclear staining was accepted as positive. Endothelial cells were strongly positive in all cases and served as an internal control. In many cases, a subset of lymphocytes also stained positive. No staining was seen in any other normal tissue. FLI-1 expression was seen in 29 of 41 (71%) ES/PNET, 7 of 8 (88%) lymphoblastic lymphomas, 0 of 8 poorly differentiated synovial sarcomas (PDSS), 0 of 32 rhabdomyosarcoma (RMS), 0 of 30 neuroblastomas, 0 of 8 esthesioneuroblastomas, 0 of 3 Wilms' tumors, 0 of 1 mesenchymal chondrosarcoma, and in 1 of 1 desmoplastic round cell tumor. This last case was known to have an EWS/WT-1 fusion. Although the EWS/FLI-1 fusion gene is specific for ES/PNET, FLI-1 protein expression is not. Significantly, the great majority of lymphoblastic lymphomas (also CD99-positive) are strongly FLI-1-positive. Immunohistochemical detection of FLI-1 may be valuable in confirming the diagnosis of ES/ PNET in cases in which molecular genetic evaluation is not feasible. FLI-1 protein expression is also helpful in distinguishing ES/PNET from other tumors that may be CD99-positive, such as PDSS and RMS. It is not surprising that some ES/ PNET are FLI-1-negative, because not all ES/PNET have the classic EWS/FLI-1, and some cases of ES/PNET may produce either low levels of protein or idiotypically different protein.

Increased macrophage infiltration of gastric mucosa in Helicobacter pylori-infected children.

The purpose of the study was to quantify gastric mucosal macrophages and define their association with the histopathologic features of stomach biopsies obtained from Helicobacter pylori-infected and uninfected children. Endoscopically obtained gastric biopsies from symptomatic children were independently evaluated by two groups of pathologists. Thirty children were evaluated; 14 were H. pylori-infected. H. pylori positivity was determined by hematoxylin and eosin (H&E), Giemsa, Warthin-Starry and an H. pylori-specific immunoperoxidase stain. A macrophage-specific, KP-1, immunoperoxidase stain was used to quantify positive cells. Inflammatory cell infiltrates were graded by severity with scores of mild to severe. Increased numbers of gastric mucosal macrophages were observed in biopsies of H. pylori-infected versus uninfected children (P < 0.05) and correlated with gastritis severity. The role of this inflammatory cell the in persistence of gastric mucosal inflammation in H. pylori infection warrants further study to develop targeted immunotherapeutic strategies.

Fetus-in-fetu with malignant recurrence.

Fetus-in-fetu is an unusual condition in which a vertebrate fetus is enclosed within the abdomen of another fetus. These occurrences are usually benign. This report describes an instance of malignant recurrence after resection of a fetus-in-fetu.

So-called congenital-infantile fibrosarcoma: does it exist and what is it?

Congenital-infantile fibrosarcoma (CIFS) is a cellular, mitotically active neoplasm with a paradoxically limited biologic potential in most cases. Its phenotype and proliferative features have been incompletely explored with inconclusive results. We studied the clinical, pathologic, immunohistochemical, and flow cytometric features of 26 cases (16 males, 10 females; 92% of cases detected within the first year life; 11 on extremities, 10 on the trunk, 5 in the head and neck). All displayed interlacing fascicles of spindle cells with focal necrosis, mitoses, and a focal hemangiopericytomatous vascular pattern. Immunohistochemically, 22 of 22 cases were reactive for vimentin. Other markers were present in a minority of cases. Flow cytometry of formalin-fixed, paraffin-embedded tissue in 10 cases demonstrated moderate to high proliferation activity and diploid DNA content in nine cases. Follow-up of all 26 patients revealed 20 patients alive and well, 15 without evidence of recurrence, and 5 with a small residual mass. Six patients had died of tumor, none had distant metastases. Patients with tumors in the head and neck or deep truncal soft tissues, including mesentery, had a poor prognosis because of local extension. CIFS is a clinically and morphologically homogeneous condition with considerable immunophenotypic diversity. Diploid DNA content in the majority of cases suggests that it may not be a fully expressed sarcoma. The clinicopathologic features are sufficiently distinctive to permit recognition and warrant conservative initial treatment in most cases. "Fibrosarcoma" is a term of convenience rather than of nosologic certainty.

Infantile sialic acid storage disease associated with renal disease.

A child with infantile sialic acid storage disease is reported. Ultrasonography demonstrated fetal ascites. At birth, the infant appeared hydropic and presented with numerous dysmorphic features, including sparse white hair, coarse facies, hypertelorism, epicanthal folds, anteverted nostrils, and a long philtrum. In addition, he had visceromegaly, bilateral inguinal hernias, and a slight gibbus deformity. Lymphocytes were vacuolated and bone marrow contained large numbers of foam cells. There were generalized vacuolations of both reticuloendothelial and parenchymal cells in the examined tissues. Neuropathologic studies revealed wide-spread neuronal storage, myelin loss, axonal spheroids, and gliosis. Neurons, endothelial cells, and Kupffer cells stained with wheat germ agglutinin indicated an accumulation of sialic acid. Free sialic acid was significantly increased in urine and serum, as well as in liver, heart, and brain tissues. The alpha-neuraminidase activity was normal. It is assumed that the basic defect of infantile sialic acid storage disease lies in impaired transport of sialic acid across the lysosomal membrane.

Electron microscopic identification of parvovirus virions in erythroid-line cells in fatal hydrops fetalis.

Intrauterine infection with parvovirus B19 may lead to fatal hydrops fetalis. Intranuclear particles, consistent with parvovirus virions, within erythroid cells were readily identified on transmission electron microscopy of formalin-preserved material obtained at necropsy from a neonate and two fetuses in whom clinical and light microscopic criteria for parvovirus B19 infection were met. No such particles were seen in similar material from a neonate and two fetuses with erythroblastosis fetalis due to alpha-thalassemia, maternofetal Rh incompatibility, and an erythrocyte membrane protein defect. When other means of investigation are impracticable transmission electron microscopy is widely available and easily performed and may be of value in establishing a diagnosis of parvovirus B19 infection.

An unusual central nervous system infection in a young immunocompromised host.

A 13-year-old girl with a ten-year history of lymphoblastic leukemia and several central nervous system (CNS) relapses developed a bone marrow relapse and accelerated CNS leukemia. Following treatment with CNS radiation and intravenous chemotherapy, she developed fever, pancytopenia, headache, and vomiting. Her neurological function deteriorated and she died on the 20th hospital day. Multiple CSF examinations failed to disclose either leukemic cells or organisms. Blood cultures obtained from a Broviac catheter yielded Micrococcus species. Postmortem examination showed meningoependymitis with intracellular coccal organisms. The pathology of this infection resembles intracranial Whipple's disease. Intracranial intracellular bacterial infection should be excluded in the infectious complications in the immunocompromised host.

Near-total pancreatectomy for hyperinsulinism. Spontaneous remission of resultant diabetes.

Persistent hyperinsulinism in the newborn may warrant surgical intervention to prevent neurologic sequelae. Subtotal pancreatectomy may not be adequate, necessitating near-total pancreatectomy with subsequent development of diabetes mellitus. We report an infant with hyperinsulinemic hypoglycemia who underwent near-total pancreatectomy. The postoperative period was characterized by insulin-dependency and extreme insulin sensitivity. Clinical follow-up and C-peptide determinations showed a return of insulin secretory capacity permitting the discontinuation of insulin therapy after five months. This experience reaffirms the potential for a favorable outcome after near-total pancreatectomy in the newborn period for severe hyperinsulinism.

Recurrent and metastatic mesoblastic nephroma in infancy.

Local recurrence or metastasis of mesoblastic nephroma is extremely uncommon. The first report of a child with mesoblastic nephroma to have both of these problems is presented. The usual course of mesoblastic nephroma is benign, with nephrectomy being curative. Adjuvant treatment is not necessary and may be lethal. However, a review of the five patients who developed locally recurrent and/or metastatic tumor indicates that chemotherapy and radiotherapy are of benefit and can produce long-term disease-free survival.

Thrombotic thrombocytopenic purpura in southeastern New England.

Eight patients with thrombotic thrombocytopenic purpura (TTP) originating within a 25-mile radius had their conditions diagnosed in a three-year period at a community teaching hospital in southeastern New England. In the preceding ten years, only one case of TTP had occurred in the same hospital. A niece-uncle relationship was present in two patients, and lymphocyte typing showed that they both shared an HLA haplotype. In the remaining patients, no social, familial, or environmental connection was established. Three patients died, all of whom were female. Six patients received exchange plasmapheresis with excellent responses in five. Autopsies in the three fatal cases showed widespread organ involvement with TTP but did not disclose evidence of any common underlying disease. This unusual occurrence should alert physicians to the possibility of localized outbreaks of TTP and the necessity of considering this diagnosis in all patients with unexplained thrombocytopenia.

Infantile osteopetrosis and neuronal storage disease.

Infantile osteopetrosis often presents with neurologic symptoms that cannot always be attributed to primary bone disease of the skull. We studied an infant with osteopetrosis and pathologic evidence of neuronal and axonal changes. This is the third case in which primary parenchymal disease of the brain was associated with infantile osteopetrosis and the first in which neuronal cytoplasmic storage was documented by light and electronmicroscopy. The simultaneous occurrence of two rare autosomal-recessive disorders, each possibly caused by an inherited lysosomal enzyme deficiency, may not be fortuitous.

Juvenile nephronophthisis with blindness in a three-month-old infant. Senior's syndrome associated with relative parathyroid insufficiency.

Juvenile nephronophthisis is a slowly progressive renal disease with onset in infancy, characterized by impaired renal concentrating ability. The combination of juvenile nephronophthisis and tapeto-retinal degeneration, renal-retinal dystrophy, may cause blindness in infancy, and renal failure in the first decade of life. This syndrome has not been previously described as a cause of renal failure in young infants. We report an infant who presented at three months of age with blindness and renal insufficiency. In addition, this infant had a disproportionate degree of hypocalcemia and hyperphosphatemia compatible with relative parathyroid gland insufficiency. We propose that this was due to an inability of this infant's parathyroid glands to undergo compensatory hypertrophy, rather than a specific defect in parathyroid function associated with renal-retinal dystrophy.

Protein-losing enteropathy in systemic lupus erythematosus.

A 12-year-old girl, who was later found to have systemic lupus erythematosus (SLE), had a protein-losing enteropathy. Histologic documentation of intestinal lymphangiectasia in the absence of congestive heart failure, retroperitoneal masses, or constrictive pericarditis marks this case as demonstrating a unique association of SLE with intestinal lymphangiectasia.

"Nephrogenic adenoma": an unusual metaplastic change of urothelium.

"Nephrogenic adenoma" is a papillary bladder lesion of uncertain pathogenesis. We have studied 2 patients with this lesion for several years with serial biopsies in both cases. We believe that the natural history of "nephrogenic adenoma" and its invariable association with bladder irritation, coupled with the histopathologic and ultrastructural findings, strongly suggest that this "tumor" represents a papillary and glandular transformation of urothelium, in response to prolonged exposure to various injurious agents. It is best regarded as a metaplastic process rather than a hamartoma or a benign neoplasm. There is no reasonable basis for supposing that the process originates from mesonephric-derived epithelium. While not itself neoplastic nephrogenic metaplasia (our preferred term) is rarely associated with the late development of invasive but not, to date, metastasizing neoplasia. Routine cystoscopy would seem the most appropriate means of following these patients.