Monosomy of chromosome 11 in pituitary adenoma in a patient with familial multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN 1) represents an endocrine syndrom e characterized by complex pituitary, parathyroid and pancreatic neoplasia. Loss of heterozygosity of the specific region 11q13 has been reported in s everal tumours from patients with MEN 1 inherited disorder. We present a ca se of a young patient with familial MEN 1 syndrome with a pituitary adenoma exhibiting monosomy of chromosome 11. The patient presented with a large a nd rapidly growing pituitary adenoma associated with markedly elevated seru m PRL levels, progressive bilateral visual loss and hydrocephalus. The rese cted adenoma was chromophobic, mainly PRL-producing and to a lesser degree immunoreactive for GH. Fluorescence in situ hybridization (FISH) using an a lpha -satellite centromeric probe detected loss of one chromosome 11 copy i n almost all pituitary adenoma cells. Clinical and biochemical studies reve aled parathyroid hyperplasia and MRI studies detected a pancreatic tumour i n addition to the pituitary adenoma. To our knowledge this is the first stu dy reporting monosomy 11 in pituitary adenoma in a patient associated with familial MEN 1 syndrome.