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PubMedDate not supplied

Cerebellar liponeurocytoma: immunohistochemical and ultrastructural study of a case.

The clinical, histopathological, and ultrastructural features of a cerebellar liponeurocytoma are reported. The tumor, a 3-cm mass localized in the right cerebellar hemisphere, was resected from a 61-year-old man clinically presenting with symptoms of intracranial hypertension. The lesion was composed of small, in some areas closely packed, medulloblastoma-like cells with prominent areas of lipidization phenomena. Moreover, mitoses, cellular atypia, and numerous vascular structures were focally observed. Glial and neuronal differentiation was immunohistochemically noted (glial fibrillary acidic protein, synaptophysin, neurofilaments, and neuron-specific enolase positivity). The p53 oncoprotein was detected in the majority of neoplastic cells and a moderate proliferation activity, evaluated by Mib-1 antibody, was focally appreciated. Ultrastructural study did not show evident neuritic processes, synapses, or dense core neuroendocrine granules. This cerebellar tumor previously called lipidized medulloblastoma and recently renamed cerebellar liponeurocytoma is considered an adult neoplasm with excellent prognosis histologically presenting prominent lipidized areas and, at the immunohistochemical and ultrastructural level, both glial and neuronal differentiation. The present study provides the first description of a less differentiated and histologically more aggressive form of this unusual tumor.

Antigens, Nuclear↗
PubMedDate not supplied

Tracheomalacia in a neonate with kniest dysplasia: histopathologic and ultrastructural features.

Kniest dysplasia is an autosomal-dominant chondrodysplastic condition characterized by disproportionate dwarfism, short trunk, small pelvis, kyphoscoliosis, short limbs, prominent joints, premature osteoarthritis, and craniofacial manifestations. The craniofacial abnormalities include tracheomalacia, midface hypoplasia, cleft palate, early onset myopia, retinal detachment, prominent eyes, and sensorineural hearing loss. Radiologic features include dumbbell-shaped femora, platyspondylia with anterior wedging of vertebral bodies, coronal clefts of thoracolumbar vertebral bodies, low broad ilia, and short tubular bones with broad metaphyses and deformed large epiphyses. This form of chondrodysplasia is associated with mutations in type II collagen splicing sequences. Mutations have been identified in the COL2A1 (type II collagen) gene between exons 12 and 24. Type II collagen is the predominant structural protein in cartilage, and mutations in this collagen account for the Kniest dysplasia phenotype. Histopathologic and ultrastructural features of epiphyseal plate cartilage have been described, but tracheal cartilage in an affected neonate has not been examined. The authors report the histopathologic and ultrastructural findings of anterior tracheal cartilage from a 35-day-old female with suspected chondrodysplasia who had tracheomalacia with airway obstruction. The tracheal cartilage was moderately cellular, but lacked cystic and myxoid changes in its matrix. The chondrocytes had abundant cytoplasmic PAS-positive inclusions. Some of these inclusions were diastase-resistant and were also highlighted on Alcian blue staining. Ultrastructural examination revealed chondrocytes with greatly dilated rough endoplasmic reticulum containing granular proteinaceous material. There were also frequent aggregates of typical glycogen. The defect in the COL2A1 gene is secondary to mutations, especially at splice junctions, and this markedly disrupts triple helix formation. The mutated type II procollagen results in intracellular retention within the chondrocytes, as abundant granular proteinaceous material within the dilated RER. A relationship is known to exist between the proportion of mutated to normal type II collagen in the matrix and the severity of the phenotype. With low levels of normal type II collagen, the phenotypic manifestations become more severe, such as in achondrogenesis type II. Both the quantity and quality of type II collagen modulates the phenotypic expression of type II collagenopathies.

Airway Obstruction↗
PubMedDate not supplied

Ultrastructural morphometry of nucleoli: potential usefulness for objective grading of clear cell renal cell carcinoma.

The authors attempted to determine the potential prognostic value of several ultrastructural morphometric parameters, including nuclear, nucleolar, and cytoplasmic features, that could be used in the objective and reproducible histological grading of clear cell renal cell carcinoma. Several nuclear and cytoplasmic parameters were assessed by ultrastructural morphometry in 26 consecutive cases of clear cell renal cell carcinoma. The nuclear and nucleolar sizes, the number of nucleoli per nuclear section and the number of marginated nucleoli, Fuhrman's nuclear grade, and Robson's stage were recorded. In addition, the proportion of cytoplasmic components was semiquantitatively estimated and compared to light microscopic appearance. Follow-up ranged from 5 to 15 years (mean = 10 years). Statistical evaluations were performed by means of the Pearson or Spearman correlation coefficient tests, and differences in survival were estimated, using the Mantel-Cox proportional risk method. Differences in survival among patients with a mean nuclear area over and under 160 microm2, and among those with a mean nucleolar area over and under 10 microm2, were statistically significant. (Cutoff points were selected at the median value for both parameters; Mantel-Cox test: chi2 = 7.102, p < .01; and chi2 = 11.096, p < .001, respectively). Fuhrman's nuclear grade (p < .01) and tumor stage at diagnosis (p < .001) were also related to survival. These data suggest that, out of all the ultrastructural morphometric features, nucleolar area is the most useful in the reproducible and accurate grading of clear cell renal cell carcinoma.

Adult↗
PubMedDate not supplied

Necrobiotic xanthogranuloma without periorbital involvement: an ultrastructural investigation.

A case of necrobiotic xanthogranuloma without typical periorbital involvement is described at the ultrastructural level. The patient, a 58-year-old Italian man, presented in 1995 with a brief history of nodulo-papular lesions commencing on the lower limbs, and mild paraproteinemia. During 6 years of follow-up, anemia, neutropenia with marked lymphopenia, and increased ESR were found, while serum cholesterol and triglyceride levels decreased from hyper to hypo values. Systemic diseases, such as diabetes, malignancy, or extracutaneous lesions, often associated with NXG, have not developed. Conventional histology was distinctive for NXG, and immunohistochemistry confirmed that dermal histiocytes were not of Langerhans cell lineage. At ultrastructure, regeneration and degeneration ("regen-degen") features were observed in some individual deep dermal histiocytes, which have not been previously documented in the literature. Identification of giant histiocytes showing 'regen-degen'' aspects might prove to be a useful ultrastructural diagnostic marker for NXG.

Cell Nucleus↗
PubMedDate not supplied

Ultrastructural and molecular heterogeneity in non-small cell lung carcinomas: study of 110 cases and review of the literature.

The authors reviewed a series of 110 surgical specimens of primary non-small cell lung carcinomas from the Department of Pathology at the Hospital Clinic, University of Barcelona Medical School, between 1987 and 1997. The sample included 25 squamous cell carcinomas, 60 adenocarcinomas, 14 large cell carcinomas, and 11 neuroendocrine tumors. Electron microscopic subcellular characteristics of the lung cancer cells were studied to define the squamous, adenoid, or neuroendocrine differentiation in each tumor. An immunohistochemical study for Cyclin D1 was performed in 96 cases. In 71 cases (65%) the author found a single ultrastructural differentiation, and in 30 cases (27%) ultrastructural differentiation was double: 25 adenosquamous and 5 adeno-neuroendocrine. In 3 cases a triple adeno-squamous-neuroendocrine differentiation was found. There were no cases of squamous-neuroendocrine differentiation. In 6 cases no differentiation of any kind could be found. Cyclin D1 overexpression was found in 58% of all tumors. The positive expression rates in squamous cell carcinoma and adenocarcinoma were 72% and 62%, respectively. In purely adenoid-differentiated tumors there was a strong association between high Cyclin D1 overexpression and differentiation (p=.006). In bronchioloalveolar carcinoma the positivity rate was 70%; all were heavy expressers, compared with 25% of heavy expressers in adenocarcinomas as a whole (p<.005). In purely squamous tumors differentiated ultrastructurally no relationship was found between high Cyclin D1 expression and degree of differentiation (p=.08). Lung cancers are morphologically and molecularly heterogeneous, and certain molecular alterations are related to specific subcellular characteristics.

Carcinoma, Non-Small-Cell Lung↗
PubMedDate not supplied

Ultrastructural study of Rasmussen encephalitis.

Rasmussen encephalitis (RE) is a well-known cause of seizures in children, manifesting histopathology of chronic inflammation of the brain. Its etiology remains unknown. Many reports have suggested the possibility of etiological heterogeneity of this disorder, including the possibility that it is caused by viral infection of the central nervous system, autoimmune phenomena, or a combination of both. The authors report ultrastructural study of 12 cases of RE. They identified most of the features of RE that have been described at the light microscopic level, but did not find any evidence of viral particles, immune complex deposits, or disruption of the blood-brain barrier except in 3 cases: intranuclear (intraneuronal) measle virus-like particles were seen in 1 patient, an electron-dense deposit in the basement membrane of the capillary of another, and a tubuloreticular body in the endothelium of a brain parenchymal capillary in a third (the first 2 rather exceptional findings were previously reported). At present, these appear to be rare findings and not reliable features of RE ultrastructure. The authors also investigated evidence of programmed cell death (apoptosis) of neurons, but only nonspecific degenerative changes of the neurons were found. At present, despite interesting light microscopic and ultrastructural features of RE, its pathogenesis remains cryptogenic.

Brain↗
PubMedDate not supplied

The ultrastructure of nasal mucosa in children with asthma.

Nasal brushing has sometimes been used to characterize some affections of the respiratory tract, but seldom employed in chronic diseases such as asthma, for the possible presence of cellular inflammation in the small specimens used for electron microscopy. The present study evaluated the ultrastructure of epithelial cells obtained by nasal brushing in 11 allergic children with asthma, before and after staying in an environment free of allergens, usually implicated in the genesis of inflammatory events. The ultrastructural alterations of the nasal mucosa have been graded on the basis of their severity. Grade I lesions were characterized by well-differentiated mucous and ciliated cells. The ciliated cells appeared usually well preserved but decreased in number. In grade II lesions, most of the epithelial surface was covered by mucous cells. A further phenotype composed of poorly differentiated ciliated or mucous cells was detected. Grade III lesions showed aspects of depletion of the ciliated and mucous cells. The epithelium was largely composed of undifferentiated cells. Furthermore, the comparison of specimens at 2 different times of sampling did not differ. The data demonstrate that in allergic children with asthma, the nasal mucosa showed ultrastructural changes, which appeared to be unmodifiable during a prolonged stay in an environment free of allergens. Moreover, the nasal epithelium may provide a convenient sampling site, allowing grade of mucosal damage, with the benefit that the brush method is minimally invasive and avoids complications related to bronchoscopic examination.

Allergens↗
PubMedDate not supplied

Molecular variability of TLS-CHOP structure shows no significant impact on the level of adipogenesis: a comparative ultrastructural and RT-PCR analysis of 14 cases of myxoid/round cell liposarcomas.

A specific TLS-CHOP fusion gene derived from the t(12;16) is present in at least 95% of myxoid/round cell liposarcomas (MLS). Rare cases of MLS show a variant t(12;22) translocation, resulting in EWS-CHOP fusion gene. The CHOP gene encodes a leucine-zipper transcription factor, which is implicated in both oncogenic transformation and inhibition of adipogenesis. To examine whether the molecular variability of TLS-CHOP or EWS-CHOP fusion transcript structure is associated with the degree of inhibition of adipogenesis, a comparative ultrastructural and RT-PCR-based analysis of 14 MLS was performed. The specimens consisted of 9 primary, 2 locally recurrent tumors, and one representative sample each from 3 patients with multifocal soft tissue metastases. Histologically, there were 8 high-grade and 6 low-grade MLS using 5% round cell (RC) component as the cutoff point. By RT-PCR assay there were 13 cases with TLS-CHOP fusion transcripts: 7 cases of type 5-2 (known as type II), 4 cases of type 7-2 (known as type I),1 case of type 8-2 (known as type III), and 1 unique case of type 6-2. The remaining 1 case showed an EWS-CHOP fusion transcript. Ultrastructural examination revealed that tumor cells were composed of a moderate-to-predominant proportion of well-formed lipoblasts in 4 cases, while in 6 cases such lipoblasts were very scant. The remaining 4 tumors were arrested in the stage of transitional cells. The heterogeneity of TLS-CHOP fusion transcript showed no apparent impact on adipogenesis, since both TLS-CHOP type I and II cases could randomly display various levels of lipoblastic differentiation. Furthermore, the 4 cases without definite lipoblasts showed no preference for any specific fusion variants and consisted of one each of TLS-CHOP subtypes. In addition, the fusion transcript variants did not correlate with other ultrastructural features, such as the presence and amount of glycogen, mitochondria, rough endoplasmic reticulum, vimentin-like intermediate filaments, and external lamina. However, there appeared to have a trend suggesting the predilections of glycogen particles and vimentin-like intermediate filaments in primitive mesenchymal cells and/or transitional cells. These findings cannot substantiate the hypothesis that the molecular variability of fusion transcripts has a biological impact on adipogenesis of MLS, and other factors might be implicated in their level of differentiation.

Adipocytes↗
PubMedDate not supplied

Ultrastructure of lamellar bodies in congenital surfactant deficiency.

Congenital surfactant deficiency (CSD) is a newly identified neonatal lung disorder associated with a variety of molecular defects affecting surfactant synthesis and secretion in alveolar type II cells. The authors present ultrastructural findings of abnormal lamellar bodies in lung biopsies from 4 infants with CSD. All were term infants presenting shortly after birth with severe respiratory failure that was unresponsive to conventional therapy and all died within the first month of life. Lung biopsies were performed between 8 and 25 days of age. Biochemical and molecular studies in 2 unrelated male infants identified SP-B deficiency, one case with 121 ins 2 mutation and the second with a 209 + 4 A > G mutation. Light microscopy in both cases showed features of alveolar proteinosis. Ultrastructurally, alveolar type II cells lacked mature lamellar bodies, and their cytoplasm contained numerous pleomorphic inclusions with membranous and vesicular structures not seen in normal type II cells. The other 2 infants were a pair of siblings in whom molecular studies identified mutations in ABCA3 transporter gene. Light microscopy showed features of acinar dysplasia and desquamative interstitial pneumonitis. TEM studies revealed absence of mature lamellar bodies in type II cells and instead showed a mixture of cytoplasmic electron-dense inclusions with concentric membranes and distinctive electron dense aggregates. The ultrastructural changes in alveolar type II cells correlated well with specific gene defect. In SP-B deficiency, the absence of mature lamellar bodies is consistent with the postulated role for this protein in the formation of lamellar bodies. The lack of mature lamellar bodies in the ABCA3 gene mutations is due to the dysfunction of this endogenous lipid transporter that targets surfactant lipid moieties to the lamellar bodies. The findings demonstrate the importance of TEM studies of lung biopsies from infants with CSD as it is a critical adjunct in the diagnosis of neonatal lung disease and in defining the underlying cellular defects.

ATP-Binding Cassette Transporters↗
PubMedDate not supplied

Ultrastructural findings and tumor necrosis factor-alpha and intercellular adhesion molecule-1 expression in psoriasis patients before and after oral cyclosporin A therapy.

Elevated levels of proinflammatory cytokines, including tumor necrosis factor-alpha, are found in skin lesions and plasma of patients with psoriasis. Clinical improvement of psoriasis with cyclosporin A treatment is accompanied by downmodulation of proinflammatory epidermal cytokines. In this study to determine the effects of cyclosporin A on the ultrastructural changes and tumor necrosis factor-alpha and intercellular adhesion molecule-1 expression in psoriasis, biopsy specimens before and after cyclosporin A treatment were evaluated ultrastructurally and immunohistochemically. Ten patients were given 3-7.5 mg/kg oral cyclosporin A for 6 months. Before and after treatment full thickness of 4-mm punch biopsies were obtained from patients and from 6 healthy volunteers. Samples were processed for electron microscopic and immunohistochemical evaluation. The treatment was well tolerated with complete clinical improvement. The ultrastructural changes such as reduction of tonofilaments, dilatation of intercellular space, and interruption in lamina densa were recovered by cyclosporin A treatment. The increased staining intensity of tumor necrosis factor-alpha and intercellular adhesion molecule-1 on epidermal keratinocytes and endothelial cells was reduced after cyclosporin A therapy. Cyclosporin A treatment results in total normalization of the electron microscopic picture of psoriasis and its beneficial effect depends on the direct inhibition of tumor necrosis factor-alpha and consequently intercellular adhesion molecule-1.

Administration, Oral↗
PubMedDate not supplied

Ultrastructure of tubular casts.

Tubular casts are found in a variety of conditions. Ultrastructural evaluation of casts has not been critically and systematically performed to define its usefulness. A total of 157 renal biopsies routinely processed for light microscopy (LM), immunofluorescence (IF), and electron microscopy (EM) were subjected to blind ultrastructural evaluation. The majority of the casts were in the distal nephron, and most of them (41.4%) were hyaline (HC). One-third (35%) of the cases showed admixed HC and granular casts (GC), and 25 cases (16%) had exclusively GC. In 7% of the cases, the morphology of the casts was distinctive enough to indicate specific composition. Four cases with red blood cell casts (5.6%) were associated with necrotizing glomerulopathy and IgA nephropathy. Four cases of myoglobulin casts were identified. Two cases with crystalized light-chain casts (1.3%) were associated with an underlying plasma cell dyscrasia. One case of acute pyelonephritis demonstrated polymorphonuclear cells casts (0.64%). A case of aminoglycoside toxicity revealed casts with myeloid bodies. Ultrastructural evaluation of casts may provide useful information that may be critical to establish or suggest a specific diagnosis.

Adolescent↗
PubMedDate not supplied

Ultrastructural changes of mitochondria in the cultivated skin fibroblasts of patients with point mutations in mitochondrial DNA.

Mitochondrial disorders represent a heterogeneous group of multisystem diseases with extreme variability in clinical phenotype. The diagnosis of mitochondrial disorders relies heavily on extensive biochemical and molecular analyses combined with morphological studies including electron microscopy. Although muscle is the tissue of choice for electron microscopic studies, the authors investigated cultivated human skin fibroblasts (HSF) harboring 3 different pathologic mtDNA mutations: 3243A > G, 8344A > G, 8993T > G. They addressed to the possibility of whether mtDNA mutations influence mitochondrial morphology in HSF and if ultrastructural changes of mitochondria may be used for differential diagnostics of mitochondrial disorders caused by mtDNA mutations. Ultrastructural analysis of patients' HSF revealed a heterogeneous mixture of mainly abnormal, partially swelling mitochondria with unusual and sparse cristae. The most characteristic cristal abnormalities were heterogeneity in size and shapes or their absence. Typical filamentous and branched mitochondria with numerous cristae as appeared in control HSF were almost not observed. In all lines of cultured HSF with various mtDNA mutations, similar ultrastructural abnormalities and severely changed mitochondrial interior were found, although no alterations in function and amount of OXPHOS were detected by routinely used biochemical methods in two lines of cultured HSF. This highlights the importance of morphological analysis, even in cultured fibroblasts, in diagnostics of mitochondrial disorders.

Cells, Cultured↗
PubMedDate not supplied

Dermatofibroma and dermatofibrosarcoma protuberans: a comparative ultrastructural study.

Dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) are dermal tumors whose histogenesis has not been well defined to date. The differential diagnosis in most cases is established in routine H/E sections and may be confirmed by immunohistochemistry, but there are atypical variants of DF with less clear histological differences and non-conclusive immunohistochemical results. In those cases, electron microscopy studies may be useful in establishing the diagnosis. The authors describe in detail the ultrastructural characteristics of 38 cases of DFSP and 10 cases of DF. The objective was to establish the ultrastructural features for differential diagnosis, and to identify the possible histogenesis of both neoplasms. DFSP is formed by stellate or spindled cells with long, slender, ramified cell processes joined by primitive junctions. Subplasmalemmal densities were frequently seen in the processes. Another common finding was the presence of multivesicular buds (MVB), peculiar structures that contain microvesicles abutting from the cell membrane. In contrast, DF is characterized by a proliferation of multiple capillary vessels with prominent endothelium and a perivascular population of ovoid or spindled cells devoid of cell processes. These latter cells featured intracytoplasmic lipid material (p < .001), infrequent subplasmalemmal densities (p < .001), and absence of MVB (p < .001). With the ultrastructural characteristics and the constant expression of CD34 in DFSP, a probable origin in dermal dendrocytes is postulated for this tumor. The histogenesis of DF is less clear, but an origin from FXIIIa modified perivascular dermal dendrocytes is proposed.

Capillaries↗
PubMedDate not supplied

Comparative ultrastructural analysis and KIT/PDGFRA genotype in 125 gastrointestinal stromal tumors.

GISTs are the most common mesenchymal neoplasms of the digestive tract and are thought to originate from or differentiate toward the interstitial cell of Cajal lineage. Almost all GISTs express KIT protein and the majority show activating mutations in either KIT or PDGFRA proto-oncogenes. Ultrastructurally, these tumors have been shown to have either a smooth muscle, neuronal, dual, or null phenotype. The objective of this study was to investigate the relationship between ultrastructural features and genotype in a large series of 125 histologically confirmed and CD117 positive GISTs. PCR analysis for the presence of KIT exon 9, 11, 13, and 17 and PDGFRA exon 12 and 18 mutations was performed. There were 62 (50%) tumors located in the stomach and 45 (36%) in the small bowel. Overall, KIT mutations were detected in 93 (75%) patients: 86 (69%) in exon 11, and 7 (6%) in exon 9. A PDGFRA mutation was detected in 7 (6%) cases and 25 (19%) cases had no mutation. Ultrastructurally, skeinoid fibers were seen in 55 (44%) cases and were more common in small bowel than stomach GISTs, and occurred in only in 1 of 16 patients with an ITD (KIT) exon 11 or PDGFRA mutation. Focal actin microfilaments were identified in 82 (65%) cases and did not correlate with location or mutation type. Rare neurosecretory-type granules (NS-G) were seen in 34 (27%) of cases, but were seen in most of the cells in only 5 (4%) cases. GISTs showing both NS-G and microtubules were associated with KIT exon 11 genotype and spindle cell morphology. PDGFRA mutated cases were associated with gastric location, predominantly epithelioid morphology and lacked NS-G.

DNA Mutational Analysis↗
PubMedDate not supplied

Inflammatory fibroid polyp of the small intestine: ultrastructural and immunohistochemical observations.

The ultrastructural and immunohistochemical features of a primary tumor of the ileum showing the classic histologic features of an inflammatory fibroid polyp (IFP) of the gastrointestinal tract are presented. Ultrastructurally the proliferating cells showed a combination of fibroblastic and histiocytic features, with abundant rough endoplasmic reticulum and active production of collagen in many of the cells and long, dendritic cytoplasmic projections with large cytoplasmic vacuoles containing remnants of phagocytosed cellular debris in others. Immunohistochemical studies showed strong cytoplasmic positivity in the proliferating cells with vimentin antibodies and scattered positivity with muramidase. Additional findings include the ultrastructural demonstration of oligocilia and occasional primitive intercellular junctions. The findings in this case suggest that IFP may represent a proliferation of primitive submucosal stromal cells exhibiting incomplete fibrohistiocytic differentiation.

Aged↗
PubMedDate not supplied

Spectrum of low-grade fibrosarcomas: a comparative ultrastructural analysis of low-grade myxofibrosarcoma and fibromyxoid sarcoma.

Low-grade fibrosarcomas have recently gained increasing attention in the literature, especially with the fall in popularity polls of the ubiquitous malignant fibrous histiocytoma (MFH). Firstly, most tumors previously known as myxoid MFH are labeled presently as myxofibrosarcomas. Secondly, the recognition and better understanding of a family of fibrosing-type fibrosarcoma, encompassing 3 members: fibromyxoid sarcoma (FMS), hyalinizing spindle cell tumor with giant rosettes (HSTGR), and sclerosing epithelioid fibrosarcoma (SEF). To expand further their understanding of the overlapping and distinct features of members included in the spectrum of low-grade fibrosarcoma, the authors carried out a comparative ultrastructural study among 15 low-grade myxofibrosarcomas (MFS) and 12 fibromyxoid sarcomas (FMS), after review of pathology and confirmation of diagnosis. The ultrastructural findings of the LG MFS identified spindle to plump cells, with abundant cytoplasm, rich in well-developed RER cisternae, often distended and sometimes cystically dilated, containing an electronlucent granular material. These results were in keeping with a well-differentiated fibroblastic-type cell phenotype. In addition, a less prominent cellular component included cells with RER, well-developed Golgi apparatus, lysosomes, and filopodia. These latter features define a fibroblastic variant with histiocytic-like properties, also known as histiofibroblasts. Myofibroblastic differentiation was quite limited and mostly absent in most of the cases. In summary, these findings recapitulate a similar spectrum with the cell constituents of so-called MFH. In contrast, the fine microscopic findings of the 12 FMS cases showed an inactive or more primitive form of fibroblastic type cells. The RER cisternae were generally underdeveloped, as expected for a generic fibroblastic-type proliferation. The cytoplasm was scant and showed a paucity of organelles, with the exception of abundant arrays of vimentin-type intermediate filaments. The very long, thin cell processes, sometimes associated with pinocytotic vesicles, were reminiscent of perineurioma ultrastructure.

Adult↗
PubMedDate not supplied

Ultrastructure as a diagnostic adjunct in the evaluation of lung allograft biopsies.

Humoral immunity contributes significantly to lung graft dysfunction. Recognizing a role of ultrastructural studies in the evaluation and diagnosis of chronic humoral allograft rejection in the kidney, the authors sought to explore its utility as a diagnostic adjunct in lung allograft biopsies. Ultrastructural studies were conducted on 44 biopsies from 26 lung transplant recipients. Endothelial cell activation and necrosis were seen in the setting of acute humoral allograft rejection. Septal chronic vasculopathic changes of thickening and lamellation of the basement membrane zone (BMZ) and BMZ collagen deposition were correlated with greater numbers of humoral allograft rejection episodes and with the development of chronic graft dysfunction/bronchiolitis obliterans syndrome. There was a positive correlation between the extent of septal fibrosis and certain chronic vasculopathic changes, namely collagen deposition in the BMZ and BMZ wrinkling. Patients with chronic graft dysfunction and multiple rejection episodes manifested low diffusion capacities (less than 50% predicted). The results indicate that ultrastructural analysis is useful in identification of septal fibrosis and chronic vasculopathy of the septal microvasculature, correlating with chronic graft dysfunction, encompassing not only fibrotic sequelae of the bronchial wall but also irreversible terminal lung parenchymal changes, the latter associated with repeated episodes of humoral rejection.

Adult↗
PubMedDate not supplied

Ultrastructure of low-grade intraosseous osteosarcoma of bone: a comparative study with fibrous dysplasia and parosteal osteosarcoma.

The ultrastructure of low-grade intraosseous osteosarcoma (LGOS) is not well documented in the literature. Four cases of LGOS are described with an emphasis on its distinguishing characteristics as well those it shares with other lesions. The predominant cells of LGOS are fibroblasts with well-developed rough endoplasmic reticulum and mild focal immunoreactivity to SMA and MSA. Few osteoblasts and myofibroblasts are present. Transition cells between fibroblasts and osteoblasts are also noted. The fibroblasts are closely related to osteoblasts from a histological and functional point of view, and phenotypically are probably modified osteoblasts. Comparative ultrastructural studies between LGOS and fibrous dysplasia (FD) reveal basic similarities, although the cells in LGOS are larger with more of an abundance of organelles. Therefore, accurate differentiation between these two lesions rests at the histological and radiological levels. LGOS and parosteal osteosarcomas (PO) also share similar ultrastructural features. In the case samples in this study, an unusual type of multilayered amorphous material was found in the osteoid matrix of a case of LGOS and one of PO. This probably emphasizes the morphologic similarities between these 2 tumors.

Adult↗