Scalp lesion

A 45-day-old boy presented to the outpatient clinic of the dermatology department with a flat scalp lesion on the space of the anterior fontanel (Figure 1). He was born full-term through spontaneous vaginal delivery, after an uncomplicated pregnancy. His parents were second-degree relatives. He received all his vaccines. The mother was negative for group B streptococcus when investigated during pregnancy.

There was a positive family history of such condition in his older brother's scalp, which resolved spontaneously within 3 weeks after labour, without any medical intervention. There was no previous history of hospitalization to the child.

At delivery, the baby's scalp lesion was 0.5 × 0.5 cm. During the first 25 days of his life, the lesion kept on raising and growing to become an isolated yellowish cyst 2 × 3 cm, after which it stopped growing (Figure 1). There were no associated haemangiomata or other congenital defects in his body.

On examination, the baby looked well and alert. He was in the 25th percentile for both height-for-age and weight-for-age. Culture from the site of the lesion showed Gram-positive cocci, consistent with Staphylococcus aureus. Ultrasound of the head showed bullae over the anterior fontanel, well-defined complex cyst, and an isolated subcutaneous lesion, with no evidence of intracranial extension. During the whole time of hospital admission, the baby was vitally stable.