A previously healthy 28-year-old woman presented to the emergency clinic with acute severe abdominal pain and high fever. A diagnostic laparoscopy was performed, during which a large retroperitoneal tumour was found. A CT-scan of the abdomen and thorax confirmed the presence of a retroperitoneal mass but also revealed multiple renal angiomyolipomas and extensive cystic lesions in all lung fields. Based on these findings, the diagnosis lymphangioleiomyomatosis (LAM) was suspected, and later confirmed by histological examination of a biopsy specimen. The acute abdomen and fever appeared to have been caused by a Streptococcus agalactiae infection of the retroperitoneal lymphangiomyoma, which was treated with intravenous antibiotics. LAM is a very rare disease affecting mostly women of childbearing age and presenting almost exclusively with pulmonary symptoms. This is the first description of LAM presenting with an acute surgical abdomen and fever due to infection of a lymphangiomyoma.