Oronasopharyngeal teratomas

Unusual Cause of Neonatal Stertor

We report a case of neonatal respiratory distress caused by an epignathus. This rare tumour, arising from the basisphenoid and protruding from the mouth, is associated with high perinatal mortality. We highlight unique clinico-radiological findings and multidisciplinary approach for a successful outcome. We review oropharyngeal teratomas reported in the literature with current management approaches.

Mature Nasopharyngeal Teratoma in a Child

Teratomas are neoplasms derived from the germ cell with components of all the three embryonic layers. These are rare neoplasms in head and neck region which can occur in any age group but are more prevalent in children. The present case is an 11-year-old girl who was brought with history of painless and progressive swelling in the oropharynx for 3 years with the associated left sided nasal blockage and nasal discharge. CT scan was suggestive of benign nasopharyngeal mass highly suspicious for lipoma. Excision of the mass was done under general anaesthesia. Peroperatively, it was a smooth, pedunculated mass arising from the left lateral wall in the nasopharynx. On cut section, it was solid to cystic mass similar to fatty tissue. Her HPE report came out to be mature teratoma of nasopharynx.

Radiofrequency coblation of congenital nasopharyngeal teratoma: a novel technique

Introduction. Congenital nasopharyngeal teratomas are rare tumours that pose difficulties in diagnosis and surgical management. We report the first use of radiofrequency coblation in the management of such tumours. Case Report. A premature baby with a perinatal diagnosis of a large, obstructing nasooropharyngeal mass was referred to the ENT service for further investigations and management. The initial biopsy was suggestive of a neuroblastoma, but the tumour demonstrated rapid growth despite appropriate chemotherapy. In a novel use of radiofrequency coblation, the nasooropharyngeal mass was completely excised, with the final histopathology revealing a congenital nasopharyngeal teratoma. Conclusion. We report the first use of radiofrequency coblation to excise a congenital nasopharyngeal teratoma and discuss its advantages.

A rare case of congenital nasopharyngeal teratoma presenting with respiratory distress

Teratomas of the head and neck are rare, benign neoplasms, usually presenting in the neonatal period and are often malignant with regard to their location. Teratomas occur with a frequency of one in 4,000 live births with head and neck teratomas accounting for <5% of the total. Extensive literature search has shown that there are only two cases congenital nasopharyngeal teratoma reported in India, and we report the third such case.

Metabolic and molecular basis of peroxisomal disorders: a review

The group of peroxisomal disorders now includes 17 different disorders with Zellweger syndrome as prototype. Thanks to the explosion of new information about the functions and biogenesis of peroxisomes, the metabolic and molecular basis of most of the peroxisomal disorders has been resolved. A review of peroxisomal disorders is provided in this paper.

RNA interference of peroxisome-related genes in C. elegans: a new model for human peroxisomal disorders

RNA-mediated interference (RNAi) for the posttranscriptional silencing of genes was used to evaluate the importance of various peroxisomal enzymes and peroxins for the development of Caenorhabditis elegans and to compare the roles of these proteins in the nematode to their roles in yeasts and humans. The nematode counterparts of the human ATP-binding cassette half-transporters, the enzymes alkyldihydroxyacetonephosphate synthase and Delta(3,5)-Delta (2,4)-dienoyl-CoA isomerase, the receptors for peroxisomal membrane and matrix proteins (Pex19p and Pex5p), and components of the docking and translocation machineries for matrix proteins (Pex13p and Pex12p) are essential for the development of C. elegans. Unexpectedly, RNAi silencing of the acyl-CoA synthetase-mediated activation of fatty acids, the alpha- and beta-oxidation of fatty acids, the intraperoxisomal decomposition of hydrogen peroxide, and the peroxins Pex1p, Pex2p, and Pex6p had no apparent effect on C. elegans development. The described analysis of functional gene knockouts through RNAi provides a basis for the use of C. elegans as a valuable model system with which to study the molecular and physiological defects underlying the human peroxisomal disorders.

Enoyl-CoA hydratase deficiency: identification of a new type of D-bifunctional protein deficiency

D-bifunctional protein is involved in the peroxisomal beta-oxidation of very long chain fatty acids, branched chain fatty acids and bile acid intermediates. In line with the central role of D-bifunctional protein in the beta-oxidation of these three types of fatty acids, all patients with D-bifunctional protein deficiency so far reported in the literature show elevated levels of very long chain fatty acids, branched chain fatty acids and bile acid inter-mediates. In contrast, we now report two novel patients with D-bifunctional protein deficiency who both have normal levels of bile acid intermediates. Complementation analysis and D-bifunctional protein activity measurements revealed that both patients had an isolated defect in the enoyl-CoA hydratase domain of D-bifunctional protein. Subsequent mutation analysis showed that both patients are homozygous for a missense mutation (N457Y), which is located in the enoyl-CoA hydratase coding part of the D-bifunctional protein gene. Expression of the mutant protein in the yeast Saccharomyces cerevisiae confirmed that the N457Y mutation is the disease-causing mutation. Immunoblot analysis of patient fibroblast homogenates showed that the protein levels of full-length D-bifunctional protein were strongly reduced while the enoyl-CoA hydratase component produced after processing within the peroxisome was undetectable, which indicates that the mutation leads to an unstable protein.

Plasma very long chain fatty acids in 3,000 peroxisome disease patients and 29,000 controls

The assay of plasma very long chain fatty acids (VLCFAs), developed in our laboratory in 1981, has become the most widely used procedure for the diagnosis of X-linked adrenoleukodystrophy (X-ALD) and other peroxisomal disorders. We present here our 17 years' experience with this assay. Three VLCFA parameters, the level of hexacosanoic acid (C26:0), the ratio of C26:0 to tetracosanoic acid (C24:0), and of C26:0 to docosanoic acid (C22:0), were measured in 1,097 males (hemizygotes) with X-ALD, 1,282 women heterozygous for this disorder, including 379 obligate heterozygotes, 797 patients with other peroxisomal disorders, and 29,600 control subjects. All X-ALD hemizygotes who had not previously received Lorenzo's oil or a diet with a high erucic acid content had increased VLCFA levels, but the application of a discriminant function based on all three measurements is required to avoid the serious consequences of a false-negative result. VLCFA levels are increased at day of birth, thus providing the potential for neonatal mass screening, are identical in the childhood and adult forms, and do not change with age. Eighty-five percent of obligate heterozygotes had abnormally high VLCFA levels, but a normal result does not exclude carrier status. VLCFA levels were increased in all patients homozygous for Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum's disease, and in patients with deficiencies of peroxisomal acyl-coenzyme A oxidase, bifunctional enzyme, and 3-oxoacyl-coenzyme A thiolase. In these patients the degree of VLCFA excess correlated with clinical severity.

Alkyl-dihydroxyacetonephosphate synthase. Fate in peroxisome biogenesis disorders and identification of the point mutation underlying a single enzyme deficiency

Peroxisomes play an indispensible role in ether lipid biosynthesis as evidenced by the deficiency of ether phospholipids in fibroblasts and tissues from patients suffering from a number of peroxisomal disorders. Alkyl-dihydroxyacetonephosphate synthase, a peroxisomal enzyme playing a key role in the biosynthesis of ether phospholipids, contains the peroxisomal targeting signal type 2 in a N-terminal cleavable presequence. Using a polyclonal antiserum raised against alkyl-dihydroxyacetonephosphate synthase, levels of this enzyme were examined in fibroblast cell lines from patients affected by peroxisomal disorders. Strongly reduced levels were found in fibroblasts of Zellweger syndrome and rhizomelic chondrodysplasia punctata patients, indicating that the enzyme is not stable in the cytoplasm as a result of defective import into peroxisomes. In a neonatal adrenoleukodystrophy patient with an isolated import deficiency of proteins carrying the peroxisomal targeting signal type 1, the precursor form of alkyl-dihydroxyacetonephosphate synthase was detected at a level comparable to that of the mature form in control fibroblasts, in line with an intraperoxisomal localization. A patient with an isolated deficiency in alkyl-dihydroxyacetonephosphate (DHAP) synthase activity had normal levels of this protein. Analysis at the cDNA level revealed a missense mutation leading to a R419H substitution in the enzyme of this patient. Expression of a recombinant protein carrying this mutation in Escherichia coli yielded an inactive enzyme, whereas a comparable control recombinant enzyme was active, providing further proof that this substitution is responsible for the inactivity of the enzyme and the phenotype. In line with this result is the observation that wild-type alkyl-DHAP synthase activity can be inactivated by the arginine-modifying agent phenylglyoxal. The enzyme is efficiently protected against this inactivation when the substrate palmitoyl-DHAP is present at a saturating concentration. The gene encoding human alkyl-dihydroxyacetonephosphate synthase was mapped on chromosome 2q31.

Immunological localization and tissue distribution of alkyldihydroxyacetonephosphate synthase and deficiency of the enzyme in peroxisomal disorders

Alkyldihydroxyacetonephosphate synthase (alkylglycerone-phosphate synthase) is a peroxisomal enzyme involved in ether phospholipid biosynthesis. The recent cloning of the cDNA encoding this enzyme from guinea pig liver enabled the raising of specific antisera against this enzyme. Both a synthetic peptide corresponding to a predicted epitope and a recombinant protein expressed in Escherichia coli were used for that purpose. Using western blot techniques, the solubilization of the enzyme from the peroxisomal membrane by Triton X-100 in the presence of salt was confirmed. Neutral hydroxylamine treatment of peroxisomes resulted in almost no release of the protein from the membrane. The complete polypeptide chain of the enzyme was resistant to proteolysis by trypsin when intact peroxisomes were studied. Carbonate treatment released alkyldihydroxyacetonephosphate synthase from the membrane indicating that the enzyme is not an integral membrane protein. This idea is in accord with the absence of a clear hydrophobic transmembrane domain in the deduced amino acid sequence of the enzyme. Alkyldihydroxyacetonephosphate synthase, as well as its mRNA, could be detected in all five guinea pig tissues examined. When using the antiserum against guinea pig recombinant alkyldihydroxyacetonephosphate synthase, a cross-reactive protein was detected in a human liver homogenate that runs at a slightly higher molecular mass. The absence of this band in liver of Zellweger syndrome and Rhizomelic chondrodysplasia punctata patients provides strong evidence that it represents the human homolog of this enzyme.