[A case of pituitary adenoma and hyperplasia with primary hypothyroidism]

A 23 year-old woman was admitted to our hospital, complaining of sterility and obesity. Her serum TSH and Prolactin were abnormally high, and her serum T3, T4 were low. Contrast-enhanced computerized tomographic (CT) scan revealed a round mass in the sella and suprasellar region. A transsphenoidal operation was then performed. The intrasellar mass was composed of a soft liquid-like part and a solid part. Only the soft liquid-like part of the mass was removed. Histological examination showed the typical appearance of chromophobe adenoma, Reticulin stain of the specimen revealed no reticular network. The remnant of the mass was considered to be hyperplasia because the size of the mass decreased on serial CT scan after thyroid hormonal replacement. Sometimes it may be difficult to distinguish between hyperplasia and adenoma. The application of reticulin stains is considered to be useful for differentiation between hyperplasia and adenoma.