Calcium deposition in human pituitary adenomas studied by histology, electron microscopy, electron diffraction and X-ray spectrometry

Incidence, Pathology, and Recurrence of Pituitary Adenomas: Study of 647 Unselected Surgical Cases

The incidence of various types of unselected pituitary adenomas based on correlation of pathologic and clinical data was assessed. We investigated 647 cases of unselected pituitary adenomas, which were surgically removed between 1980 and 1993. All cases were examined by immunohistochemistry and electron microscopy. The mean age of patients was 44.0 years with 40.0 years for women (55.2%) and 49.1 years for men (44.8%). Age distribution indicated a remarkable sex difference: 52.4% of women and 26.8% of men were between 21 and 40 years at the time of surgery. Based on immunohistochemistry and electron microscopy, prolactin (PRL) cell adenomas represented 263% of tumors, growth hormone (GH) cell adenomas 12.5%, adrenocorticotrophic hormone (ACTH) cell adenomas 12.4%, oncocytomas 12,4%, and gonadotroph cell adenomas 9.4%. Seventy-three percent of the prolactinomas occurred in women and 73.8% of the oncocytomas were found in men. The incidence of pediatrics pituitary adenomas was 4.6%. All 647 cases were followed up; the mean follow-up period was 96.6 months. In 40 patients (6.2%), the adenoma recurred. Recurrence was common in functioning ACTH cell adenomas (8 cases: 9.5%) followed by silent adenomas (7 cases: 25.9%). Recurrence was noted after 2-96 months (average 28.7 months) following surgery. The shortest remission period was found in a patient with oncocytoma followed by a patient with prolactinoma.

Ultrastructural study of early stage of calcification in herpes simplex encephalitis

A case of herpes simplex encephalitis was investigated at the ultrastructural level. Herpes simplex virions were observed, both in nuclei and perikarya of degenerated cells in the cerebrum. Needle-shaped mineralized precipitates were also present in the disintegrated cells. These mineralized depositions were confined to mitochondria. This finding suggests that mitochondria serve as initial nidus of calcification in herpes simplex encephalitis.

Histological classification of pituitary disease

Morphological features of pituitary disease are classified according to increased and decreased hormone production to allow clinical correlation with pathological processes. Increased hormone synthesis and secretion may be due to pituitary adenomas or carcinomas derived from the five hormone-secreting cell types, or to extrapituitary stimuli causing hypertrophy and hyperplasia of those cells. Various tumour-like conditions can mimic functioning adenomas. Rarely, no lesion is detected and intrinsic abnormalities of adenohypophyseal cells are implicated. Hypopituitarism can be selective or generalized. Diffuse hormone deficiency is usually attributable to tissue destruction by tumours, inflammatory or infiltrative conditions or vascular lesions. Congenital abnormalities of pituitary development may result in hypophyseal dysfunction. Hypothalamic abnormalities may cause generalized hypopituitarism or may involve only selective releasing factors and hormones. Feedback inhibition and receptor abnormalities may be implicated in pituitary hypofunction, and selective deficiencies may be the result of genetic abnormalities, immune reactions or toxic damage to one cell type.