SURGICAL PATHOLOGY OF ENDOCRINE AND ...

34 R.V. Lloyd et al.
Fig. 5 Gonadotroph adenoma
A) H&E section of a
gonadotroph adenoma.
B) Immunohistochemical
staining for FSH in a
gonadotroph adenoma. The
tumor cells in the upper portion
of the field are diffusely positive
for FSH. Scattered positive cells
are present in the non-neoplastic
pituitary.
C) Ultrastructure of a
gonadotroph adenoma with
polar cells containing long
cytoplasmic processes and
secretory granules. X4000.
D) Ultrastructure of a
gonadotroph adenoma in a
female patient showing vacuolar
transformation of the Golgi
apparatus (‘‘honeycomb
Golgi’’). X11000
Histopathologic examination shows chromophobic
tumors with papillae or a diffuse growth pattern (Fig. 5A).
Gonadotroph adenomas in men usually show variable
immunoreactivity for FSH and/or LH (Fig. 5B). In
women, the tumors show weak and sparse immunoreactivity
for FSH and/or LH.
Ultrastructural studies also show sexual dimorphism
[46] (Fig. 5C,D). The male-type gonadotroph adenomas
show dilated rough endoplasmic reticulum, prominent
Golgi complexes, and small but sparse secretory granules,
about 200 nm in diameter (Fig. 5C). Oncocytic changes
with increased numbers of mitochondria may be present.
Gonadotroph adenomas in women (‘‘female-type’’) contain
a unique honeycomb Golgi complex, with the sacculi
present as clusters of spheres containing a low density
proteinaceous material (Fig. 5D). The secretory granules
are small, around 200 nm in diameter [7, 9, 35].
Plurihormonal Adenomas
Plurihormonal adenomas are tumors producing hormone
from more than one lineage [47, 48]. ACTH cells arise
from a distinct lineage, which is influenced by specific
transcription factors that are important for their development
[49, 50]. These include Ptx1 and NeuroD1 [35].
The GH, PRL, and TSH adenomas have a common
lineage, which is influenced by specific transcription factors
such as Pit-1, Prop 1, and Lim 3 [35]. Gonadotroph cells
(FSH/LH) developments are influenced by another group of
transcription factors including: Ptx1, Lim 3, and SF-1 [35].
Mixed GH-PRL Adenomas
These tumors are composed of densely granulated GH
cells and sparsely granulated PRL cells. The H&E sections
show mostly acidophilic cells with chromophobic
cells. Immunohistochemistry shows GH and PRL immunoreactivity
in different cell types.
Acidophil Stem Cell Adenomas
These adenomas are associated with hyperprolactinemia,
usually in younger patients. Histopathologic features
include chromophobic or slightly acidophilic tumors.
Immunohistochemical staining shows positive staining
for PRL with less intense staining for GH. Ultrastructural
features include one cell type with lactotroph and somatotroph
features, such as unusual granule extension