We reported a case of a 26-year-old female who was referred to our clinic with the diagnosis of possible acromegaly. She was born from a term pregnancy by forceps delivery. The patient was diagnosed as having hip luxation at one month and spoke her first word at 15 months. She had been diagnosed at the age of 9 years old as having perinatal encephalopathy with intellectual and motor affectation. Since this period of time she has undergone an insidious change in her appearance, mainly comprising progressive coarsening of the face. For this reason she was submitted to our clinic with presumed acromegaly. Dynamic tests of growth hormone secretion ruled out such a diagnosis. The Patient was considered as having "acromegaloidism", a term used for patients whom manifest clinical features of acromegaly but do not present a demonstrable growth hormone hypersecretion. Subsequently cytogenetic evaluation revealed an infrequent chromosome pattern: X-Tetrasomy. In the present article a differential diagnosis of acromegaloidism and the potential role of genes present on X-chromosome involved in human growth such as SHOX gene are discussed. Overdosification of SHOX gene might explain tall stature of girls with X-tetrasomy. Our observation suggested that X-tetrasomy should be considered in the differential diagnosis of acromegaloidism. Furthermore, this may lead to the identification of new genes in the X-chromosome that are important for growth of facial structures.