Unusual features in a patient with neurofibromatosis type 1: multiple subcutaneous lipomas, a juvenile polyp in ascending colon, congenital intrahepatic portosystemic venous shunt, and horseshoe kidney

We report a case that draws attention to a hitherto undescribed association of neurofibromatosis type 1 (NF1) with juvenile polyp, congenital intrahepatic portosystemic venous shunt, multiple subcutaneous lipomas, and horseshoe kidney. Our patient has fulfilled the National Institutes of Health consensus conference criteria for NF1 by having neurofibromas, axillary freckling, Lisch nodules, and café-au-lait spots. There is no family history of NF1 and his 7-year-old son has no stigmata of NF1. On the other hand, the patient's family had a presumably dominant inheritance of horseshoe kidney: the father, proband, sister, and son of the other sister had a horseshoe kidney. The patient was investigated for mutations in the NF1 gene and PTEN, but no germline mutations were detected. The differential diagnosis for such a collection of hamartomatous, cutaneous, and vascular disorders includes the Proteus, Bannayan-Riley-Ruvalcaba, and Cowden syndromes. None of these diagnoses was convincingly confirmed in this patient.