We report an uncommon mitochondrial variant in a baby girl with congenital hyperlactataemia and Leigh syndrome. The patient presented with a single episode of generalised clonic convulsion at day 19, and was found to have isolated and persistent hyperlactataemia ranging from 3.34 to 9.26 mmol/L. She had elevated serum lactate-to-pyruvate ratios of up to 35 and high plasma alanine concentration, indicative of a respiratory chain defect. At the age of 8 months, she developed evolving neurological and imaging features compatible with Leigh syndrome. Genetic testing for common mitochondrial DNA mutations, large mitochondrial DNA deletions, and selected nuclear genes was negative. Further analysis of lymphocyte mitochondrial DNA by sequencing revealed an uncommon heteroplasmic variant, NC_012920.1(MT-ND5):m.13094T>C (p.Val253Ala), which was previously shown to reduce complex I activity. In patients in whom there was a high suspicion of mitochondrial disorder, entire mitochondrial DNA analysis may be warranted if initial screening of common mitochondrial DNA mutations is negative.

A patient with chronic obstructive pulmonary disease developed a cough, loss of consciousness, and convulsions during an air flight. Chest radiography showed a large lung bulla. Computed tomography of the brain showed intraparenchymal air and bilateral cerebral infarcts. The findings were compatible with cerebral air embolism, most likely predisposed to by lung bulla and an air flight. The underlying pathology and possible treatment are discussed.

Classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency is a well-known disorder of sexual development (previously known as ambiguous genitalia) in genotypic female neonates. We report on a 66-year-old Chinese, brought up as male, with a simple virilising form of congenital adrenal hyperplasia associated with Turner's syndrome (karyotype 45,X/47,XXX/46,XX). His late presentation was recognised due to his exceptionally short stature and persistent sexual ambiguity. His condition was only brought to medical attention as he developed a huge abdominal mass, which later turned out to be a benign ovarian mucinous cyst. It is therefore important to look out for co-existing congenital adrenal hyperplasia in patients with Turner's syndrome and virilisation, after the presence of Y chromosome material has been excluded.

Congenital pseudarthrosis of the clavicle is a rare clinical entity, first described in 1910. We report on a newborn baby girl who presented with a painless lump over mid-portion of right clavicle at her routine newborn examination, which was subsequently diagnosed as a congenital pseudarthrosis. Here we explore its pathogenesis, elaborate on its differential diagnoses in paediatric patients, and comment on its distinct radiological features.

Carotid cavernous fistula is a well-documented but rare condition in pregnancy, about which there are a limited number of reports in the literature. We report such a case in a 41-year-old woman presenting with right-sided headache, proptosis, and diplopia at 37 weeks of gestation. She was subsequently diagnosed to have carotid cavernous fistula based on angiography. Embolisation was performed in the postpartum period. Carotid cavernous fistula has the potential of serious morbidity including visual loss and intracranial haemorrhage. It can be treated effectively by endovascular embolisation, which confers a good prognosis. Although headache is a common complaint during pregnancy, obstetrician should be aware of this condition if the clinical presentation is suspicious.