The paper describes the case of a 4-year-old boy with spontaneous pneumomediastinum secondary to a large bronchopneumonic focus, treated with supportive therapy including rest, painkillers, antibiotics and oxygen, which resolved in a short time with total remission of symptoms. Pneumomediastinum, also called mediastinal emphysema, identifies a clinical condition characterized by the presence of free air in the mediastinum and can be spontaneous or traumatic. Spontaneous pneumomediastinum is not associated with previous pathological events, such as trauma, endoscopic bronchial procedures, invasive ventilation and it is classified in primary and secondary to underlying disease. In 70-90% of cases it occurs in children with risk factors. Early diagnosis is critical for its management and, although the course of this disease is typically benign, hospitalization and observation are important because of possible significant and life-threatening complications.

Cystic lymphangiomas are rare benign tumours of childhood resulting from an abnormal development of the lymphatic system, most commonly arising in the head and axillary regions. Abdominal cystic lymphangiomas are rare, accounting for approximately 5% of lymphangiomas. Their clinical presentation is various, ranging from incidental finding of abdominal cyst to acute abdominal presentation. The paper reports the case of a one-year-and-nine-month-old boy, who presented with a two-day history of abdominal pain, diarrhoea and biliary vomiting. Clinical examination revealed slight abdominal tenderness with a painless palpable mass. Imaging was consistent with a cystic lesion, occupying the entire abdomen and displacing intestinal loops with suspected vascular impairment. Urgent laparotomy was undertaken and a large cystic mass was found, arising from the mesentery with volvulated ileum loop and with confirmed signs of ischemic suffering. Histological examination revealed the nature of the lesion as a cystic lymphangioma.