Case 3 -
Choroid Plexus Xanthogranuloma
(Bilateral Xanthogranulomata of the Choroid Plexus Glomera Choroidea)
Gregory N. Fuller
M.D. Anderson Cancer Center
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A 60-year-old man presented with a right upper lobe lung mass and bilateral mass lesions of the
Diagnosis: Choroid plexus xanthogranuloma (bilateral xanthogranulomata of the choroid plexus
Incidental mass lesions of the choroid plexus
The two incidental mass lesions of the choroid plexus with which every pathologist should be familiar
are cystic degeneration and xanthogranuloma . Cystic degeneration is a common accompaniment of aging
and although often visually striking has no pathologic significance. Only exceptionally rarely does
cystic change reach a size capable of causing obstructive hydrocephalus. Xanthogranuloma of the choroid
plexus occurs less frequently than cystic change but is still relatively common. In most cases the
lesions are small, only a few millimeters in diameter, and typically exhibit a vivid tan-to-yellow color
on gross examination. Cases with recent hemorrhage are mottled black and yellow on cut section.
The most striking histologic feature of choroid plexus xanthogranuloma is the conspicuous presence of
cholesterol clefts. Upon closer microscopic examination, prominent multinucleated giant cells are seen
attempting to engulf the cholesterol crystals. Recent and remote hemorrhage with hematoidin and
hemosiderin deposition is another characteristic feature and may provide an etiologic clue as discussed
below. A number of associated reactive changes are also typically seen, including foamy macrophage
infiltration, fibrosis and secondary calcification. In contrast to solitary choroid plexus metastasis,
overtly malignant cells are not seen.
Histologic Features of Choroid Plexus Xanthogranuloma
| Cholesterol crystal clefts|
| Multinucleated giant cells of foreign body-type|
| Recent hemorrhage|
| Remote hemorrhage with hematoidin and hemosiderin deposition|
| Macrophage infiltration|
| Fibroblast proliferation and fibrosis|
Some neuropathologists favor dividing the xanthomatous lesions of the choroid plexus into two
categories: xanthomas and xanthogranulomas . Xanthomas are composed purely of foamy lipid-laden
macrophages, whereas xanthogranulomas have, in addition, prominent hemosiderin deposition and cholesterol
crystals with the typical associated foreign body-type giant cell reaction. This distinction has
etiologic connotations: at least one study has reported an association of xanthomas with hyperlipidemia,
analogous to systemic xanthomas arising in a similar clinical context. In contrast, there is no
association between hyperlipidemia and choroid plexus xanthogranulomas and their origin and
pathophysiology are obscure. One hypothesis is that the initiating event is an intra-choroid hemorrhage,
which is followed by red blood cell breakdown, cholesterol crystal formation, giant cell reaction,
hemosiderin deposition, calcification and fibrosis.
Although many investigators have argued that "cholesterol granuloma" is a more appropriate
designation, the term "xanthogranuloma" is firmly entrenched in the literature and in the
Incidence, location and treatment
The xanthogranulomata seen in the present case were incidental findings. Autopsy series have noted
incidental xanthogranulomas of the choroid plexus in 1-7% of the population
. Symptomatic choroid
plexus xanthogranuloma is relatively uncommon but does occur
. Most patients present with
obstructive hydrocephalus and the attendant general signs and symptoms of increased intracranial
pressure, although more unusual clinical manifestations, such as parosmia and parageusia, have
occasionally been noted . Treatment consists of surgical resection to relieve the hydrocephalus and
The most common anatomic location for xanthogranuloma within the choroid plexus is in the largest
tuft, which is located in the atrium of the lateral ventricle and is called the glomus choroideum (pl.
glomera choroidea) . Incidental glomus choroideum xanthogranulomas are frequently bilateral, as in
the present case, but may also be unilateral.
Symptomatic xanthogranulomas most commonly arise in the lateral ventricle choroid plexus of adults.
However, symptomatic xanthogranulomas have also been reported in the third ventricle
children, in which they are often bilateral
Differential Diagnosis: Isolated unilateral or bilateral metastasis to the choroid plexus
Isolated metastasis to the choroid plexus (CNS metastatic disease limited to the choroid plexus in the
absence of parenchymal metastasis) is very rare with an estimated incidence of only 0.14% of all cerebral
. Of all systemic primary cancers, renal cell carcinoma in particular shows a
propensity for choroid plexus metastasis . Isolated choroid plexus metastasis as the presenting
condition in the absence of a known primary is exceptionally rare. Bilateral choroid plexus
xanthogranuloma is far more common than isolated bilateral choroid plexus metastasis and most cases of
bilateral choroid plexus xanthogranuloma are usually recognized by the radiologist. In unilateral
xanthogranuloma cases, the possibility of solitary metastasis is often entertained, particularly in
patients who have a history of a systemic malignancy. Even in this setting, however, xanthogranuloma is
more common than solitary metastasis to the choroid plexus. Nevertheless, surgery is sometimes performed
on suspicion of metastasis from a known or unknown primary tumor, and it is therefore incumbent upon the
surgical pathologist to be familiar with the histopathologic features of this entity.
Similarly, at autopsy, upon sectioning the brain and seeing a large yellow-black mass in one or both
glomera choroidea, the pathologist's first thought is likely to be metastasis, particularly if the
patient has a history of cancer. An awareness of choroid plexus xanthogranuloma, however, can temper
this rush to judgment. Histologic sections provide an unequivocal diagnosis.
Other intraventricular mass lesions
Xanthogranuloma is one of limited number of circumscribed mass lesions that are confined to the
intraventricular anatomic compartment and that are treated primarily by surgical resection . The
principal entities in the differential diagnosis of a circumscribed intraventricular mass lesion are
listed in the Table.
Intraventricular Mass Lesions
| Choroid plexus papilloma / atypical papilloma / carcinoma|
| Intraventricular (choroid plexus) meningioma|
| Isolated metastasis to the choroid plexus|
| Xanthogranuloma of the choroid plexus|
| Chordoid glioma of the 3rd ventricle|
| Colloid cyst of the 3rd ventricle|
| Central neurocytoma|
| Subependymal giant cell astrocytoma|
| Fetus (intracranial intraventricular fetus-in-fetu)|
Equine Choroid plexus Xanthogranuloma
Mass lesions of the choroid plexus identical to the xanthogranulomas seen in humans frequently occur
in horses, where they are commonly referred to as cholesterol granulomas or cholesterinic granulomas
. They are in fact more common in horses than in humans and are age-associated with an incidence
of 15-20% in older horses. As in humans, equine choroid plexus xanthogranulomas are often bilateral. A
majority, as in humans, are asymptomatic, but they may occasionally attain massive size, filling both
lateral ventricles. Afflicted horses typically present with seizures or with gait and balance
disturbances secondary to obstructive hydrocephalus
Choroid plexus xanthogranulomas have rarely been reported in other animal species, such as the
fat-tailed dwarf lemur , but in no other species is xanthogranuloma as common as in horses and
humans. The explanation for why humans and horses share this peculiar predilection for choroid plexus
xanthogranulomas is unknown.
Species Incidence of Choroid Plexus Xanthogranuloma
| Humans || 1-7%|
| Horses || 15-20%|
| Other species || rare isolated case reports|
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