NQ-042 Answer:
(A) Craniopharyngioma
Pathology:
The specimen is that of a midline sagittal section
of a brain. Part of the pons and the optic chiasma are included in the
picture. Can you identify them? The location of the lesion suggests that it
is a suprasellar cystic lesion with compression of the optic chiasma and
base of the brain. The salient pathologic change is a well demonstrated
unilocular cystic lesion with a papillary growth. If you pay attention, you
may see that the solid part of the lesion also contain many small cysts.
Photographic consideration:
The trick to take a photo that could illustrate the
three dimensional structure of the papillary growth is to immerse the
specimen in water to let the structures float and then take a photo.
Craniopharyngioma:
General:
Is an uncommon but not rare tumor that occurs
predominantly in children and young adults. However, it is the most
frequent supratentorial tumor in children. Most of them are suprasellar
and about half of all cases have a intrasellar component. Occasionally,
they are found entirely intrasellar. Rare cases limited to the optic
chiasma, sphenoid bone, pharynx, and cerebellopontine angle have been
reported. Craniopharyngioma is also the most frequent tumor arising from
the
pharyngeal pituitary gland- a vestigial structure during formation
of the pituitary gland. Imaging studies typically reveal a cystic
structure with calcification.
Macroscopically, many craniopharyngiomas are cystic with and without solid component. The
consistency may be tough and gritty on cutting due to calcifications.
The cystic fluid is brown or yellow and oily, typically it is being
described as “machine oil” like. Examination of air dried and unstained
smear of cystic fluid under polarized light would reveal birefringent
cholesterol crystals.
Histologically, most of them demonstrate the adamantinomatous pattern that contains
components resembling ameloblastoma and squamous odontogenic tumor
arising in the jaws. The less common form is the papillary
craniopharyngioma. This subtype is limited to adults and does not
contain the "machine oil" content.
Germinoma
is a germ cell tumor that often occur in the supra sellar area. In fact,
incidence of germ cell tumor in suprasellar region is very uncommon although
it is only second in incidence to its most common location, the pineal area.
Germinoma typically occurs as invasive solid tumor. In less common cases,
the tumor may grow diffusely without forming a definable mass. The cut
surface is soft, friable. Depending on the amount of hemorrhage, it varies
from grayish pink to hemorrhagic. Mixed germ cell tumor containing other
germ cell tumor components including endodermal sinus tumor (yolk sac tumor)
and embryonal carcinoma are common; choriocarcinoma component is less common
but may also occur. Germinoma with these heterologous elements are often
more hemorrhagic.
Hypothalamic neuronal
hamartoma
occurs as well-defined solid expansion of the
hypothalamus. Many of them would occur as a pedularated nodule arising from
the hypothalamus. Most of the cases are asymptomatic.
Precocious puberty and hypothalamic dysfunctions are the most common
symptomatic manifestations. Some of the cases are associated with
Pallister-Hall
syndrome.
Pituitary adenoma
of this size is in the macroadenoma category.
They are typically solid tumor and some of them have a cystic component.
Pituitary adenoma is usually intrasellar but may have a suprasellar
component. Cystic dilatation with papillary growth to the extent being
demonstrated in this photo is uncommon.
Choroid plexus papilloma: Although there are papillary structures to
suggest a choroid plexus papilloma, the cystic component is unusual. The
other unusual feature is that there is no choroid plexus in the surpasellar
area which makes choroid plexus tumor quite unlikely.
Photograph is kindly
provided by Dr. John Trojanowski.