This is possibly a sinus
which is congenital in nature meaning it has been present from birth due to some embryological defect during closure of the abdominal wall. Therefore it secretes some sort of fluid occasionally. It has a propensity to get infected and cause inflammation. Sometimes, it can connect with an underlying tract most commonly the urinary tract
in which case it is labeled as a fistula. Management comprises of a contrast study to underline the tract followed by surgical excision to remove all the contents of the cavity.