Calcified concretions in the anterior pituitary gland of the fetus and the newborn: a light and electron microscopic study.

Calcified concretions including typical laminated psammoma bodies can be detected on routine hematoxylin-eosin (H&E) examination of fetal and neonatal anterior pituitary glands. This finding has seldom been reported in the literature and, to the authors' knowledge, no ultrastructural examinations of fetal or neonatal pituitary calcifications have been reported to date. In this study, histological sections of anterior pituitary glands from 200 fetuses and infants ranging in age from 15 weeks of gestation to 1 year of life revealed calcified concretions in all the cases up to 1 month of life. They decreased in incidence postnatally and were not found after 6 months of age. Most were round to ovoid, basophilic or eosinophilic, often laminated, and measured between 5 and 30 microm in diameter. Immunohistochemical stains showed that the calcifications followed no particular pattern of distribution among the most prevalent pituitary cell types. Ultrastructural examination revealed small single or multiple intracellular calcified deposits, and larger, sometimes laminated, extracellular calcifications, suggesting an intracellular origin for the concretions with cell death occurring concomitant with their formation. This phenomenon, which to some extent resembles the formation of psammoma bodies in certain tumors, seems to represent a distinctive morphological type of developmental cell death. Apoptosis, a more common form of developmental cell death, was also found in some of the sections. Pathologists should be aware of the fact that calcified concretions represent a normal finding in the anterior pituitary gland of fetuses and young infants. Their mere presence in cases of fetal or perinatal demise with no other pertinent findings should not be attributed to intrauterine viral infections or ischemic-anoxic events.