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Neurogenic tumours of the larynx are unusual, with approximately 115 cases reported in the literature to date. Most of these lesions are benign, solitary submucosal nodules which present with hoarseness and are amenable to surgical resection. We present a case of a large pedunculated schwannoma arising in the aryepiglottic fold associated with sudden asphyxial death in an otherwise healthy young female.

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Metaplastic breast carcinoma refers to a heterogeneous group of neoplasms in which the typical glandular growth pattern of the tumor undergoes metaplasia, either epithelial or stromal. A 59-year-old woman presented with a breast mass that recurred in 1 year and showed invasion of the chest wall. Histological sections of both the tumor and the recurrence showed a tumor composed predominantly of stromal spindle cells with neoplastic epithelial ducts. Squamous metaplasia was seen in some ducts. Immunohistochemical staining showed positive cytokeratin and epithelial membrane antigen staining of the epithelial cells. Smooth muscle actin, S100, and vimentin were diffusely positive in the stromal cells. Electron microscopy of the original lesion showed cells with squamous epithelial and smooth muscle characteristics, and other cells that formed lumens into which microvilli projected. Electron microscopy of the recurrent lesion showed primarily spindle-shaped cells with abundant tonofilaments in the perinuclear cytoplasm, desmosomes with associated tonofilaments, filaments with focal densities, often aligned parallel with the cell membranes, surface attachment plaques, and fragments of basement membrane. Pinocytotic vesicles were rare. These metaplastic cells are derived from myoepithelial cells which are multipotential and able to differentiate into epithelial or stromal cells.

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PURPOSE: To examine histopathologically the endothelium of contrast-enhancing spinal nerve roots. METHODS: In five adult baboons, chronic compression of the left S-1 spinal nerve root sufficient to produce a change in the evoked potential was produced by means of a suture tied around the nerve. The animals were studied with MR at 8 and 16 days after nerve compression and then killed for histopathologic and electron microscopic studies. Histopathologic changes in the nerve roots demonstrating contrast enhancement were described. RESULTS: In all compressed spinal nerves, contrast enhancement was observed. Histopathologically, wallerian degeneration of the root and inflammation and disruption of the endothelium of capillaries in the spinal nerve were evident. CONCLUSIONS: Degenerative changes in the nerve root and the capillary endothelium of a lumbar spinal nerve are associated with contrast enhancement.

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GM1-gangliosidosis (GM1) is one of the metabolic storage diseases, of which a differential diagnosis requires an array of biochemical assays to determine the enzyme deficiency. This approach is not only time-consuming and costly but also unavailable to most hospital laboratories. However, a presumptive diagnosis of GM1 may be made on the basis of coarse facial feature, foamy endothelial cells in the cutaneous blood vessels and ectopic Mongolian spots, if present. A more definitive diagnosis of GM1 is then made on the demonstration of deficiency of GM1 beta-galactosidase in leukocytes, plasma or cultured skin fibroblasts. Thus, a battery of enzyme tests may be averted.

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The term "inflammatory myofibrohistiocytic proliferation" (IMP) has been proposed to replace the conventional designations of plasma cell granuloma and inflammatory pseudotumor. Three cases of extrapulmonary IMP in children are reported, including an intracerebral lesion which has been formerly undescribed. In children, IMP may be associated with microcytic hypochromic anemia, hypergammaglobulinemia, and high erythrocyte sedimentation rate. In this clinical setting, differentiation of a rapidly growing but benign IMP from a bona fide sarcoma is of paramount importance.

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An 8-year-old girl presented with cutaneous lymphoma without bone marrow or visceral involvement. The tumor cells displayed convoluted and invaginated euchromatic nuclei. The immunophenotype of these cells was non-T/non-B (Ia+, CALLA-, SIg-, TdT-, E-, Thy-). The skin lesions regressed promptly with chemotherapy including cyclophosphamide, vincristine, methotrexate, doxorubicin, and cytosine arabinoside. Six months after the completion of chemotherapy (18 months postdiagnosis), the patient had a relapse of the skin lesions with concurrent bone marrow involvement. The cutaneous infiltrate at relapse was morphologically and immunophenotypically similar to that at the onset of illness. However, the bone marrow infiltrate, although morphologically similar to the cutaneous tumor, had an immunophenotype consistent with T-cells (Ia+, CALLA-, SIg-, E-, TdT+, Thy+, OKT4+, OKT8+). As in adults, primary cutaneous non-T/non-B lymphomas in children may be derived from T-cells or their precursors.

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In immunocompromised patients with cerebral toxoplasmosis, the tachyzoite forms rather than cystic and bradyzoite forms of the protozoon are commonly seen. These tachyzoites are minute, scattered among cellular debris, sometimes lodged inside macrophages and neutrophils, and difficult to visualize by light microscopy, even with special stains. Immunodiagnostic tests may be falsely negative due to inability of the host to produce appropriate antibodies. Isolation of the organism is dangerous because Toxoplasma gondii is highly infective. In this situation, transmission electron microscopy (EM) may be a diagnostic tool of choice. It demonstrates the fine definitive features of the protozoon and can be expedited to give results in five hours. Further evaluation of EM for diagnosing possible toxoplasmosis in immunocompromised patients is indicated.

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This report describes an exceptional example of cerebral neuroblastoma in association with neoplastic glial cells, which were frequently arranged in clusters around the supporting blood vessels. The neuroblastic nature of the tumor was confirmed by the presence of numerous dense-core vesicles in the cell processes. The glial nature of the associated cells was confirmed by their positivity for glial fibrillary acid protein by immunoperoxidase staining and by the presence of abundant cytoplasmic filaments of intermediate size on electron microscopy. Of particular interest was the presence of dense-core vesicles in some of the glial cells, and that of a basal lamina underlying the perivascular glial cells. The tumor was interpreted as a composite cerebral neuroblastoma and astrocytoma. No undifferentiated neuroepithelial stem cells could be identified. The cytogenesis of this mixed neuroepithelial neoplasm is uncertain.

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Tubuloreticular inclusions (TRI) have been observed in the rough endoplasmic reticulum of blood lymphocytes and monocytes in two cases of Reye's syndrome initiated by influenza infections. Tubuloreticular inclusions are seen in these mononuclear leukocytes during the acute phase of illness, but not during convalescence. Since TRI have been demonstrated in peripheral mononuclear leukocytes in patients with acquired immunodeficiency syndrome, systemic lupus erythematosus, and certain viral infections including T-cell leukemia, it may be that the finding of TRI in Reye's syndrome reflects a viral infection and/or immune dysfunction, if such association is not proved to be fortuitous.

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We have studied three round cell sarcomas from pediatric patients in tissue culture to compare the electron microscopic morphology of cells in culture to cells from original biopsy specimens. None of the original tumors displayed distinctive features by light microscopy that would allow classification of a specific tumor type, and electron microscopy was not helpful in identifying specific morphologic features that would allow further classification of tumor types. However, electron microscopy of cells in culture from the three neoplasms revealed distinctive morphologic features that did allow further classification of all three tumors. Cells from an inguinal lymph node, which were cultured in soft agar tumor colony-forming assay, revealed Z-bands and actin and myosin filaments indicative of a rhabdomyosarcomatous nature for the tumor. Cells from 5-day, 10-day, and 4-month cultures of a bone marrow metastasis of a second tumor revealed features of skeletal muscle in the young cultures and neuroblasts in the older culture, suggesting a primitive neuroectodermal neoplasm. Cultured cells from the third tumor, a neoplasm of the calf in an infant, displayed large lakes of glycogen, typical of cells of Ewing's sarcoma, which were not present in the cells examined from the original lesion. Ultrastructural studies of cells in culture have the potential to add morphologic data that may be useful to further define and classify a neoplasm, as illustrated in the 3 cases reported here.

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Cerebral blastomycosis may simulate a brain tumor. Its diagnosis is sometimes very difficult. The morphologic identification of the fungus may be misleading because it shares some common features with many other dimorphic fungi. Culturing and conversion of the organism from mycelial phase to yeast phase are not always successful. Immunofluorescent staining of the biopsy tissue is useful in confirming the diagnosis. However, a combination of double immunodiffusion (DID) test and complement fixation (CF) test makes the diagnosis more accurate and reliable. The direct role of macrophages in defending the host against blastomycosis is illustrated by electron microscopy.

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Two cases of multilocular renal cyst (MRC) are presented with electron microscopic findings. The epithelial cells of the cysts resembled renal collecting tubule cells and not convoluted tubule or Henle's loop cells. Intercystic areas contained only connective tissue elements. Simple MRC appears to be a congenital malformation that results from segmental maldevelopment of the ureteric bud. In some cases of MRC, the intercystic septa contain immature renal elements. The lesion is then called cystic poorly differentiated nephroblastoma (CPDN). However, in both MRC and CPDN, local recurrence or metastases have not been described. Treatment of these lesions should consist of nephrectomy, careful histologic evaluation to rule out obvious foci of Wilms' tumor, and conservative follow-up.

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Immature rats were reserpinized to determine whether the model used for adults may be suitable for the study of pancreatic exocrine insufficiency seen in infants with cystic fibrosis. Rats were reserpinized by injections either into pregnant dams or into newborn rats. The dose of reserpine used by others was lethal to immature rats, so lower doses were used. Pancreas from 1-day-old fetal-treated pups was hypoplastic, but concentration of chymotrypsinogen was elevated. At age 7 days hyperplasia was seen. When rats were reserpinized as neonates, hypoplasia and decrease in all parameters measured was observed at age 7 days. Progressive recovery occurred during the following 2 weeks in both groups. Electron microscopic study of the fetal-treated 24-hr-old pancreas revealed evidence of acinar cell degeneration with the presence of abnormal zymogen granules. At age 7 days the pancreas from neonatal-treated rat pups appeared to have a reduced number of granules. At ages 14 and 21 days the pancreas was similar to that seen at age 7 days except that the granules were larger and some acinar lumina were filled with a finely granular, homogeneously dense material. It is concluded that prenatal and neonatal reserpinization of rats induces changes in pancreas similar to those found in cystic fibrosis.

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The ultrastructural pathology of nerve and muscle and the neurological dysfunction in children with cholestatic liver disease and vitamin E deficiency have not been previously correlated. We studied two children with this syndrome. One child, 11 years of age, had severe hyporeflexia and decreased vibratory sense. Nerve conduction was delayed. The second child, 2 years of age, was neurologically normal. Both children showed ultrastructural evidence of damage to the sural nerve and accumulation of electron-dense deposits in the muscle fibers. Abnormalities of the nerves included disruption of the myelin sheath and separation and degeneration of the inner and outer components of the Schmidt-Lanterman incisure.

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Methotrexate (MTX) and 6-mercaptopurine (6MP), the two drugs most commonly used for maintenance treatment of childhood leukemia, are both potent hepatotoxins. In order to assess MTX-6MP-induced damage, we obtained biopsies from 11 children with acute lymphocytic leukemia (ALL) for light microscopic and transmission electron microscopic study. Prednisone, vincristine, and L-asparaginase were used for induction of remission in all patients. Although light microscopic findings were minimal, we found significant ultrastructural abnormalities in all patients. Changes included nuclear abnormalities, disruption of rough and smooth endoplasmic reticulum, a variety of mitochondrial changes, steatosis, fibrosis, and changes in peroxisomes and lysosomes. These abnormalities could not have been predicted from liver function tests or histopathology. Three of the eleven patients studied had also received cyclophosphamide and cytosine arabinoside during maintenance therapy. The ultrastructural abnormalities in this group were not distinguishable from those observed in the group that did not receive these additional chemotherapeutic agents. The long-term clinical significance of these findings is not known.

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Electron microscopic studies of various tissues from virus-infected newborn mice disclosed a consistent form of viral cytonecrotic ultrastructural lesion in divergent types of cells (myocardial, valvular fibroblastic, aortic, exocrine and endocrine pancreatic, and hepatic cells) due to three different picornaviruses (coxsackieviruses B4 and B1 and encephalomyocarditis virus). The lesion is characterized by numerous membrane-vesicle complexes, margination of nuclear chromatin or nuclear pyknosis, dilation of rough endoplasmic reticulum, inflammation, and, at times, mitochondrial swelling. It seems apparent that the finding of this ultrastructural type of cytonecrosis is characteristic of a picornaviral infection regardless of the tissue involved and the offending member of the picornavirus group.

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The ultrastructural changes in the vessels of the fingertips of patients with Raynaud's phenomenon or disease, with or without scleroderma, are described for the first time. Fingertip specimens were taken by punch biopsy. The light microscopic changes, including segmental vasculitis, fibrinoid degeneration of capillaries, and involuntary regression of glomus bodies explain the reduced digital blood flow associated with Raynaud's disease and phenomenon. The moment-to-moment digital blood flow, recorded rheoplethysmographically, was low when the patient was in a comfortable environment and was increased in a hot environment. This result substantiates the therapeutic importance of reflex vasodilatation. These findings correlate well with the ultrastructural changes in capillaries, including multiple cytoplasmic folds in endothelial cells, abundant intracytoplasmic filaments, and unusual incorporation of collagen fibrils in the basement membrane. These changes must influence nutritional and thermoregulatory function of the digital blood vessels.

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