You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is A 3-week-old child presents with an abdominal mass. What is the most common cause of the presentation? and explain in detail?
c. Multicystic dysplastic kidney(Ref: Nelson's 20/e p 2555)Multicystic dysplastic kidney is the most common cause of an abdominal mass in the newborn, but the majority are nonpalpable at birth.