Marfan syndrome (MFS) is an autosomal dominant disorder that is prone to fibrodysplasia, lens dislocation and rapid height growth, which needs to be distinguished from gigantism. This article reports a 14-year-old patient with MFS who had a typical binocular lens subluxation in both eyes, with visual impairment and rapid height growth. MRI with contrast to the pituitary suggested a pituitary microadenoma, but growth hormone and insulin-like growth factor 1 were in the normal range, thus excluding gigantism or acromegaly. Non-functional pituitary adenoma was considered. MFS patients need long-term follow-up and multidisciplinary collaboration, and attention should be paid to cardiovascular system monitoring and genetic testing, which can be helpful for the diagnosis and treatment of patients and risk prevention and control.