Arginase deficiency with new phenotype and a novel mutation: contemporary summary.

In areas without expanded newborn screening, instead of presenting neonatally, patients with arginase deficiency typically present with spastic paraplegia in early childhood. Diagnosis of this rare neurometabolic disease poses the first challenge because it is often misdiagnosed as cerebral palsy during initial stages. We describe arginase deficiency in a 20-year-old woman with spastic paraplegia, progressive dystonia, dementia, peripheral neuropathy, epilepsy, liver cirrhosis, and non-B/non-C hepatocellular carcinoma. A novel homozygous mutation NM_000045.2 (ARG1):c.673del (p.Arg225GlyfsX5) was detected. We suggest that all children presenting with progressive neurodegeneration or spastic paraplegia in the absence of risk factors for cerebral palsy should be screened for inborn errors of metabolism, including arginase deficiency. For monitoring urea cycle defects, noninvasive imaging screening for liver fibrosis and hepatocellular carcinoma can help ensure early detection, with potential treatment implications.

Medications as causes of intraluminal hyperdensities: what radiologists need to know.

In computed tomography (CT) angiogram or some dedicated CT studies of the abdomen, the use of positive enteric contrast should be avoided as its presence could decrease the sensitivity of the test. There are, however, cases of CT scans with unexpected hyperdense intraluminal contents detected due to the use of certain oral or rectal medications. Reports on medications as causes of intraluminal hyperdensities are sparse in the English literature. We have studied several commonly used medications and revealed that many drugs appear hyperdense in CT scans. The presence of unexpected intraluminal hyperdensities can potentially cause erroneous interpretation of images and in some cases decrease the sensitivity of the test. The hyperdense bowel contents may be mistaken as acute hemorrhage in CT angiogram for detection of GI bleeding. Active GI bleeding, presented as intraluminal extravasation of contrast material, can also be obscured. Certain intra-abdominal pathologies could be masked, for example, in plain CT scan for detection of urinary tract stones or in contrast CT study for suspected bowel ischaemia. It is important for radiologists and clinicians to be aware of this situation in order to prevent misinterpretation of images and to select the most appropriate imaging modality when such unexpected intraluminal hyperdensities are encountered.