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 syndrome characterized by complex pituitary, parathyroid and pancreatic neoplasia. Loss of heterozygosity of the specific region 11q13 has been reported in several tumours from patients with MEN 1 inherited disorder. We present a case of a young patient with familial MEN 1 syndrome with a pituitary adenoma exhibiting monosomy of chromosome 11. The patient presented with a large and rapidly growing pituitary adenoma associated with markedly elevated serum PRL levels, progressive bilateral visual loss and hydrocephalus. The resected adenoma was chromophobic, mainly PRL-producing and to a lesser degree immunoreactive for GH. Fluorescence in situ hybridization (FISH) using an alpha-satellite centromeric probe detected loss of one chromosome 11 copy in almost all pituitary adenoma cells. Clinical and biochemical studies revealed parathyroid hyperplasia and MRI studies detected a pancreatic tumour in addition to the pituitary adenoma. To our knowledge this is the first study reporting monosomy 11 in pituitary adenoma in a patient associated with familial MEN 1 syndrome.