|Incidence of Pituitary adenomas|
Histologic studies of pituitary glands obtained from unselected
routine adult autopsies show the presence of incidental adenomas
in 8 to 23 percent, suggesting that transformation in
adenohypophyseal cells is a relatively common event, albeit one that is not
always apparent clinically.
The pituitary gland is a common substrate for
neoplastic transformation, giving rise to approximately 15 percent of all
diagnosed intracranial tumors.
The adenohypophysis is a functional endocrine unit composed of three
anatomic parts: the pars distalis (anterior lobe), pars intermedia
(intermediate lobe), and pars tuberalis (a sleeve of adenohypophyseal cells
ensheathing the lower hypophyseal stalk). The pars distalis is the site of
meticulously regulated hormone synthesis and release, and is also the
principal site of clinically significant intrasellar pathology. Tumors
arising from adenohypophyseal cells represent the most common form of
primary neoplasia occurring in the sellar region. The overwhelming majority
of these tumors are histologically benign adenomas, and although many
exhibit varying degrees of local invasiveness, exceptionally few demonstrate
the metastatic dissemination necessary for the designation pituitary
carcinoma. Even so, the' 'benign" histology of pituitary adenomas is often
an all too beguiling feature of their biology, for the regularity with which
they encroach on critical neural structures, coupled with the distressing
endocrinopathies they frequently induce, make them a frequent and
significant source of patient morbidity and, occasionally, patient
The neurohypophysis, which includes the infundibulum, pituitary
stalk, and posterior pituitary, rarely gives rise to clinically significant
primary tumors. Granular cell tumors of the posterior lobe and pituitary
stalk, though relatively common as incidental autopsy findings, rarely grow
large enough to be of clinical significance. The remaining tumors of
neurohypophyseal origin are gliomas, which are very rare. By contrast, the
neurohypophysis is one of the favored intracranial recipient sites for
metastatic disease. Metastatic deposits emanating from a variety of systemic
malignancy are not uncommonly in the posterior
lobe, and although most of these occur in the setting of advanced systemic
disease, occasionally a posterior lobe deposit is the first manifestation of
a unrecognized neoplastic process.
Pituitary adenomas have place in the common population in 25%,
according to postmortum studies performed in several centers. Most of
them are microadenomas and could be multiple. Most of the died were not
complaining of them.
For some reasons, these microadenomas start to grow and regain variable
hormonal activity. In the case that, they are active hormonally, they
could be detected in the early stage.
When the pituitary adenoma hormonally inactive, then the clinical signs
become evident when mass compression to the surrounding structures start
to manifest the clinical presence of the pituitary adenomas.
Clinically diagnosed pituitary adenomas consist 15% of extra-axial
intracranial tumors. The are usually benign in behavior, but when they
become large, they regained morbidity with the expansion.
Clinical presentation discussed elsewhere, and the neuroradiologic and
hormonal studies with the detailed evaluation of all the neural
structures surrounding the mass is mandatory to have the proper decision
In the past, the mortality rate was high in the surgical
treatment of pituitary adenomas. Introduction of microscopic facilities
and microsurgical techniques with improvement of the neurosurgical
approaches not only lowered the mortality, but also the morbidity and
negative drawbacks of the surgical intervention.
In 1985 I had a patent for the new surgical subfrontal approaches
to the chiasmal region with mobilization and preservation of the
olfactory tracts. These approaches are designed to the giant pituitary
adenomas with massive suprasellar extension. The important point here is
not the patent, but these modifications brought with them an entire
package of surgical standards and concepts, that I realized that
performing more than thousand operations in pituitary adenomas over 25
years, I never had mortality.
Thanks to the great neurosurgeon Prof. Tigliev G.S. who spent all
the seconds of his life perfecting the neurosurgical standards in
Leningrad. He died 2003, but he is living in our heart and all my
experience is a continuum the way of his