ABSTRACT
OBJECTIVES: While the complete form of trisomy 22 is seemingly incompatible with life, the mosaic form is a rare syndrome associated with developmental delays, intellectual disability, and dysmorphic features. Due in part to the difficulty of analyzing chromosomal mosaicism, many instances either go undiagnosed or have their diagnosis delayed. We report a case of mosaic trisomy 22 in a diamnionic-dichorionic twin with marked growth discordance and intra-uterine growth restriction, diagnosed in a 2-year-old with developmental delays, sensorineural hearing loss, cardiac and gastrointestinal abnormalities, and osteopenia of prematurity. Evaluation with a chromosomal oligonucleotide microarray with SNP analysis did not detect any copy number variants. Fibroblast metaphase karyotype analysis from a skin biopsy, however, showed trisomy 22 which was confirmed by FISH. Follow-up peripheral blood karyotype analysis and FISH studies revealed a normal male karyotype. This case highlights an instance where classical cytogenetics from two separate tissue types can provide a diagnosis that is more cost-effective than microarray analysis in assessing pediatric developmental delay. Trisomy 22 is the second most common aneuploidy in spontaneous miscarriages and has a nondescript and variable phenotype, especially in cases of mosaicism. As such, this condition may be underdiagnosed using the current recommended testing algorithm. Chromosomal microarray is considered first tier testing in an unrecognized phenotype with whole exome or whole genome sequencing, often performed on peripheral blood, as second tier testing. Diagnoses such as mosaic trisomy 22 suggest the second tier of testing in undiagnosed cases should also include a recommendation to look at alternative tissue types.
ABSTRACT
OBJECTIVE: The purpose of this study is to determine a concentration of iodinated contrast media in saline and 5% dextrose in water (D5W) for organ hydrodissection, a technique used to physically separate and protect tissues adjacent to thermal ablations. MATERIALS AND METHODS: A total of 28 samples were prepared from 1:1000-1:1 iohexol or iothalamate meglumine contrast media in either normal saline or D5W. Samples alone or juxtaposed with a homogeneous liver-mimicking phantom were imaged by CT using 80-120 kVp and 10-300 mAs. Mean CT numbers and noise were measured from the fluid, background air, phantom adjacent to the fluid, and phantom distant from the fluid. Visibility was determined from the contrast-to-noise ratio between the fluid and phantom, whereas streaking artifact was quantified by relative noise in the phantom. Measures were individually fit using multiple linear regression to determine an optimal contrast-to-fluid ratio for increased visualization without streaking. Contrast media- and blood-doped saline and D5W were also tested to determine whether such doping altered their electrical conductivity. RESULTS: Iohexol concentration most influenced CT number; volumetric ratios of 1:1000-1:1 produced 20 HU to over 3000 HU. CT numbers were weakly dependent on x-ray tube voltage, whereas contrast-to-noise ratio and streaking artifacts were somewhat dependent on tube output. An optimal ratio of iohexol in fluid was determined to be 1:50. There was no significant difference between the electrical impedances of doped and pure saline or D5W (p > 0.5, all cases). CONCLUSION: A 1:50 ratio of iohexol in saline or D5W provides an optimal combination of increased visibility on CT without streaking artifacts.
