<<

. 9
( 10)



>>

to prognosis. (continued on next page)




Skin and Soft Tissues 575
G


F




H I




11-15. (Continued) F. Advanced malignant melanoma
on the sole of the foot of an African man. Malignant
melanomas are rarer in darkly pigmented individu-
als, and when they occur, they tend to occur on non-
pigmented areas such as the sole of the foot or the
palm of the hand. G. Merkel cell carcinoma resem-
bles a basal cell carcinoma in appearance grossly. The
Merkel cell in the epidermis is a neural crest-derived
cell. The carcinoma behaves in an aggressive fashion.
H. Histology of a Merkel cell tumor. The dermal in¬l-
trate of small, dark blue, malignant Merkel cells (bot-
tom) may be mistaken for lymphoma or secondary
small cell cancer of the lung by the unwary. I. Sweat
gland“derived adenocarcinoma of the skin “ without
histology, the speci¬c type of carcinoma cannot be
diagnosed. The cut surface shows a lobulated, slightly
mucoid-looking tumor invading the subcutis.




576 Skin and Soft Tissues
A




B

11-16. A. Angiosarcoma of the skin showing the
characteristic reddish-violaceous hue of the main
lesion (center right). Several smaller metastatic
tumor nodules are also evident. B. This bisected
angiosarcoma has such a marked degree of vascu-
larity that it mimics an area of hemorrhage.




Skin and Soft Tissues 577
A




11-17. Cysts in the neck. A. Branchial cyst (lym-
B
phoepithelial cyst) occurs in the anterolateral part
of the neck. This cyst is seen to have a smooth lin-
ing and a thick wall due in part to the presence of
lymphoid tissue external to the epithelial lining.
B. Thyroglossal tract cyst that was lined by squa-
mous epithelium; abundant lymphoid tissue is
present, accounting for the partly solid appearance.




578 Skin and Soft Tissues
A




C
B

11-18. Soft tissue lesions related to “trauma.”
A. Organizing hematoma of soft tissues following
blunt trauma. B. Piece of pine needle embedded in
soft tissue of the hand. C. Transverse section of the
same specimen con¬rms the plant-type arrangement
of the internal structure of the foreign object. (con-
tinued on next page)
Skin and Soft Tissues 579
D



11-18. (Continued) D. Lipid-rich ¬brous masses
removed from the buttock: myospherulosis. E. His-
tology of myospherulosis shows clusters of erythro-
cytes surrounded by a membrane-like deposit of
lipid-rich material following a prior injection. The
condition may mimic a fungal infection.




E




580 Skin and Soft Tissues
A




B




11-19. A. Cavernous hemangioma of soft tissues
adjacent to a large vein. The hemangioma shows
focal thrombosis (white areas) within which focal
calci¬cation is noted (yellow specks). B. Lymphan-
gioma of soft tissues shows multiple interconnect-
ing spaces containing no blood.




Skin and Soft Tissues 581
11-20. Fibrous histiocytoma is a benign tumor com-
posed of lipid-¬lled histiocytes accounting for its
yellow color naked eye.




582 Skin and Soft Tissues
A




B




C




11-21. Benign tumors of adipose tissue. Cytogenetic
alterations may assist in separating lipomatous soft
tissue tumors. A. Encapsulation is the only feature
that separates this lipoma from normal adipose tis-
sue in appearance. Lipoma may show rearrange-
ment of chromosome 12q in 75% of cases. B. Intra-
muscular lipoma is sited within a skeletal muscle.
Such tumors tend to occur in the thigh or trunk of
middle-age adults. C. Histology of this intramuscu-
lar lipoma shows well-differentiated ¬broadipose
tissue (left) abutting on skeletal muscle (right). (con-
tinued on next page)




Skin and Soft Tissues 583
D E




F




11-21. (Continued) D. Fibrolipoma is a lipoma that
contains increased amounts of ¬brous tissue perme-
ating the adipose tissue. The white streaks of
¬brous tissue are clearly evident on the cut surface
G
of the tumor. E. Hibernoma is a rare tumor of young
adults that occurs in the scapular region and shows
differentiation toward brown fat. Rearrangement of
chromosome 11q is observed. F. Lipoblastoma, a
rare benign tumor affecting children younger than
7 years, usually occurs super¬cially in the limbs
and shows rearrangements of chromosome 8.
Grossly, lipoblastoma shows a prominent lobulated
pattern. G. Typical histologic lobulation of a mature
lipoblastoma. Patient showed cytogenetic rearrange-
ment of chromosome 8q. Lipoblastoma is a benign
lesion and matures into a lipoma if not removed.




584 Skin and Soft Tissues
A



11-22. Well-differentiated liposarcomas commonly
occur in the retroperitoneum or the limbs. Myxoid
and round cell liposarcomas occur in the limbs of
adults. A. Atypical lipomatous tumor (well-differ-
entiated liposarcoma; sarcoma-like variant). About
45% of liposarcomas are well differentiated. Bizarre
stromal cells may be found in the ¬brous septa.
Ring chromosome is derived from the q13“15
region of chromosome 12. B. Histology of a well-
differentiated liposarcoma shows an appearance not
all that dissimilar to normal ¬broadipose tissue.
Some variation in nuclear size and shape and stain-
ing qualities are noted. (continued on next page)




B




Skin and Soft Tissues 585
C



11-22. (Continued) C. Low-grade myxoid liposar-
coma presents a more solid appearance than normal
¬broadipose tissue, and it has a glistening, slimy
appearance in areas re¬‚ecting its myxoid nature. A
zone of necrosis and hemorrhage is evident on the
right side of the specimen. D. Histology of a pure
myxoid liposarcoma (a low-grade tumor) shows
bland-looking spindle-shaped cells with a myxoid
background and a “chicken wire fence” pattern to
the blood vessels. (continued on next page)




D




586 Skin and Soft Tissues
E




F

11-22. (Continued) E. Round cell liposarcoma is a
poorly differentiated form of a myxoid liposarcoma;
hence, the myxoid naked eye appearance of this
tumor. F. This dedifferentiated liposarcoma has the
gross appearance of a solid, fatty-looking tumor
without distinguishing features. Dedifferentiated
liposarcoma may evolve from recurrence of a previ-
ously excised liposarcoma, and in addition to
lipoblasts, it may contain areas resembling a malig-
nant ¬brous histiocytoma histologically.




Skin and Soft Tissues 587
A




B




11-23. A. Neuro¬broma of soft tissues has a myx-
oid, edematous-looking cut surface. The appearance
can be variable, and the lesion is not encapsulated
like a schwannoma. Unlike the latter lesion, a neu-
ro¬broma contains axons (revealed by silver stains)
scattered throughout its substance. B. Plexiform
neuro¬broma of the popliteal nerve has expanded
the nerve, making excision not feasible. This patient
had type 1 neuro¬bromatosis. (continued on next
page)


588 Skin and Soft Tissues
C




11-23. (Continued) C. Malignant peripheral nerve
D
sheath tumor (MPNST, neuro¬brosarcoma) present-
ing as a solid, white tumor with focal areas of
degeneration and microcyst formation. Half of these
tumors arise in von Recklinghausen syndrome (in
association with chromosome 17 deletion and p53
mutations), and the other half arise de novo. D. His-
tology of a MPNST showing abundant collagen pro-
duction by the malignant cells.




Skin and Soft Tissues 589
A




11-24. A. Small encapsulated schwannoma (neurile-
moma) removed from the vocal cord shows no sign
of degeneration. B. Larger schwannoma of soft tis-
sues shows areas of cystic degeneration. (continued
on next page)



B




590 Skin and Soft Tissues
C




11-24. (Continued) C. Histology of a schwannoma
shows faint nuclear palisading, plus prominent
blood vessels in a collagen-rich stroma. D. Malig-
nant schwannoma of a limb shows in¬ltration into
adjacent skeletal muscle.



D




Skin and Soft Tissues 591
11-25. Myxoma of soft tissues shows a characteris-
tic myxomatous, mucoid cut surface. Myxoma
occurs most often in the thigh of adult females. Mul-
tiple myxomas may occur in Carney™s syndrome.



11-26. A. Elasto¬broma removed from posterior
chest wall shows a yellow-white, imperfectly cir-
cumscribed mass within skeletal muscle. The lesion
is believed to represent a reactive process involving
abnormal elastogenesis. Local resection is curative,
unlike ¬bromatosis, which requires wider excision.
B. Histology shows multiple bands of elastin
embedded in dense ¬brous tissue.

A
B




592 Skin and Soft Tissues
B
A



11-27. Fibromatosis. A. Fibromatosis of the foot that
recurred after multiple excisions. Note the solid yel-
low-white tissue expanding the foot and in¬ltrating
between the bones of the foot. B. Fibromatosis
(desmoid tumor of anterior abdominal wall mus-
cles) in a patient with Gardner syndrome. The
lesion exhibits a characteristic whorled, ¬brous-
looking cut surface. C. Histology shows small
peripheral nerves embedded in dense ¬brous tissue.




C




Skin and Soft Tissues 593
A




11-28. Endometriosis of soft tissues. A. This gross
lesion shows no evidence of iron deposits related
to previous hemorrhage from the displaced endo-
metrium. The lesion cannot be diagnosed without
histology. B. Histology shows proliferative phase
endometrial glands and stroma.



B




594 Skin and Soft Tissues
A B

11-29. Proliferative myositis. A. A whitish-colored,
tumor-like mass lies alongside darker-colored skele-
tal muscle at the site of a preexisting fascial plane.
The surgeon is often concerned that the lesion may
be a sarcoma. B. Histology shows plump, ganglion-
like, spindle-shaped cells arising from a ¬broblastic
background. The histology is slightly reminiscent of
proliferative fasciitis. The cells are myo¬broblastic
in nature, and simple excision is all that is needed
to cure the lesion.




Skin and Soft Tissues 595
A B



11-30. A. Massive soft tissue leiomyoma presenting
as a pelvic mass in a male. B. Leiomyosarcoma of
soft tissue showing central necrosis rimmed by
recent hemorrhage. C. Histology of a well-differen-
tiated leiomyosarcoma.




C




596 Skin and Soft Tissues
11-31. A. Solitary ¬brous tumor (SFT) of soft tissues
presenting as a lobulated, intermuscular solid mass.
B. Histology of SFT shows a hemangiopericytoma-
tous-like pattern with prominent small blood ves-
A
sels between the tumor cells.




B




Skin and Soft Tissues 597
A




11-32. A. Benign chondroma of soft tissues. B. Soft
tissue chondrosarcoma shows central necrosis and
hemorrhage secondary to its rapid growth.


B




598 Skin and Soft Tissues
A




11-33. A. Synovial sarcoma of sole of the foot is pre-
B
senting as a smoothly rounded mass. B. Histology
shows a monophasic (spindle cell) synovial sar-
coma. (continued on next page)




Skin and Soft Tissues 599
C




11-33. (Continued) C. Transverse section of resected
lower leg shows synovial sarcoma on either side of
the interosseous membrane. D. Malignant ¬brous
histiocytoma of soft tissues shows no gross distin-
guishing features. The entity is shrinking as more
lesions are separated off from this diagnosis.



D




600 Skin and Soft Tissues
A



11-34. A. Embryonal rhabdomyosarcoma (ER) in a
young child presenting as a misleadingly bland-
looking lesion that is reminiscent of a nasal polyp
or accumulation of mucus “ referred to as the botry-
oid subtype of ER. B. Histologically, the ER is com-
posed of small round malignant cells.




B




Skin and Soft Tissues 601
A




B




11-35. Miscellaneous tumors of soft tissues.
A. Osteogenic sarcoma of soft tissues that showed
histologic evidence of new bone formation. The
tumor shows extensive areas of hemorrhage at its
periphery. B. Fibrosarcoma of soft tissues present-
ing as a ¬‚eshy, circumscribed mass with an area of
necrosis at its inferior margin (arrow). (continued
on next page)




602 Skin and Soft Tissues
C




D




11-35. (Continued) C. Metastatic plasmacytoma
E
under the skin. D. Yolk sac (endodermal sinus)
tumor of the retroperitoneum is usually a malignant
tumor. (Yolk sac tumors are the most common
malignant testicular and ovarian tumors in chil-
dren.) E. Histology of yolk sac tumor shows that the
primitive germ cells have produced an ill-formed
glomeruloid body (arrow). (continued on next page)




Skin and Soft Tissues 603
F




11-35. (Continued) F. Mature teratoma of the
G
retroperitoneum has a multicystic internal structure
with focal solid areas. G. Histology of this teratoma
shows a variety of well-differentiated tissues resem-
bling bronchial cartilage, spaces lined by bronchial
epithelium, arteries, and lymphoid tissue.




604 Skin and Soft Tissues
A




11-36. Metastatic tumors in soft tissues. A. Metasta-
tic renal cell carcinoma has a deep yellow color due
to its abundant lipid content. B. Metastatic malig-
nant melanoma (MM) in skeletal muscle. An MM
should be considered in any metastatic tumor of
uncertain origin.



B




Skin and Soft Tissues 605
11-37. Cystic hygroma (lymphatic dysplasia) at
back of neck of a fetus. A. Front view of a gener-
ally hydropic fetus showing an halo-like cystic
hygroma colli behind the head. B. Posterior view of
a cystic hygroma after the ¬‚uid contents have been
drained. Cystic hygroma may be associated with
chromosomal abnormalities (including Turner syn-
drome, as in this patient) and/or congenital heart
disease. Fetal Turner syndrome comprises cystic
hygroma, generalized edema, and constrictions at
A
the wrists and ankles.




B




606 Skin and Soft Tissues
12 Central Nervous System



A




12-1. A. Close-up view of a small berry aneurysm
B
(arrow) on a cerebral artery. B. Precursor defect
leading to a berry aneurysm is a localized gap in
the medial muscle where only intima and adventi-
tia comprise the vascular wall. The defect is begin-
ning to bulge outward. Such defects may have a
familial basis accounting for the familial occurrence
of some berry aneurysms. C. Elastic-stained section
of berry aneurysm at vascular branch point shows
absence of muscle and internal elastic lamina in the
wall of the aneurysm. (continued on next page)




C




Central Nervous System 607
D




E




F




608 Central Nervous System
A




B

12-2. A. Coronal section of brain adjacent to site of
rupture of a berry aneurysm shows that a jet of
blood has entered the cerebral substance to produce
an intracerebral hematoma. B. A more posterior
coronal section of the same brain shows more blood
in the Sylvian ¬ssure plus signi¬cant brain swelling
leading to a right-to-left shift.




Facing page:
12-1. (Continued) D. Subarachnoid hemorrhage. The blood lies deep to the arach-
noid membrane and cannot be washed away by applying a gentle jet of water
to the surface. E. Large ruptured berry aneurysm of circle of Willis. F. Large berry
aneurysm (top) shows a coil protruding through its ruptured wall. The radiolog-
ically inserted coil had induced thrombosis but failed to prevent fatal bleeding.


Central Nervous System 609
A




C

12-3. Hypertensive pontine hemorrhage. A. A transverse sec-
tion of the cerebellum and brainstem shows a large hematoma
in the dorsal aspect of the mid pons. B. Two more levels ros-
tral to the prior section show extension of the pontine hemor-
rhage to involve the rostral portion of the fourth ventricle.
B
C. Coronal section of the same brain at the level of the anterior
commissure showing dilatation of the lateral ventricles second-
ary to compression of the fourth ventricle by the hematoma.




610 Central Nervous System
12-4. Intraventricular hemorrhage in a premature
neonate. A. Photo of base of the brain shows sub-
arachnoid hemorrhage in the area around the brain-
stem and the cerebellum. This pattern of hemor-
rhage suggests that the blood has tracked out from
within the ventricular system. B. Coronal section of
cerebral hemispheres shows extensive intraventric-
ular blood in both lateral ventricles, the right tem-
poral horn plus the third ventricle. This is the clas-
sical appearance of hemorrhage into the ventricles
secondary to hemorrhage into the subependymal
germinal matrix in premature infants. (continued on
A
next page)




B




Central Nervous System 611
C




D

12-4. (Continued) C. Transverse sections through
the brainstem and the cerebellum showing blood in
the cerebral aqueduct and the fourth ventricle with
extension into the subarachnoid space. D. Histology
shows a small hemorrhage in the region of the
subependymal germinal matrix. Such hemorrhages
are the source of large intraventricular hemorrhages
seen in premature infants.




612 Central Nervous System
12-5. A. Brain of an infant who survived an intra-
ventricular hemorrhage shows brownish discol-
oration and thickened leptomeninges at the base of
the brain. B. Close-up view of the same region. C.
Coronal section of this same brain shows hydro-
cephalus with dilatation of the lateral and third
ventricles and accentuation of the temporal horns
of the lateral ventricles. The old hemorrhage has
given rise to brownish discoloration of the lining of
A
the ventricles. (continued on next page)




B




Central Nervous System 613
C




D

12-5. (Continued) D. Section of the midbrain,
medulla, and cerebellum of the same patient shows
a dilated cerebral aqueduct in the midbrain, as well
as dilated foramina of Luschka in the lateral aspects
of the medulla. This pattern is indicative of a com-
municating type of hydrocephalus, the obstruction
being distal in the ¬‚ow of cerebrospinal ¬‚uid (CSF).
Note the thickened leptomeninges over the medulla
(bottom). Such leptomeningeal scarring interferes
with the ¬‚ow of CSF to sites of resorption in the
arachnoid granulations.




614 Central Nervous System
A



12-6. Cerebral infarction. A. Hemorrhagic infarct in
the area of distribution of the right middle cerebral
artery. The right hemisphere is swollen, and there is
local disruption of the surface by hemorrhage. B. Lat-
eral view of the same brain shows extensive cerebral
softening with disruption of the surface and sur-
rounding subarachnoid hemorrhage. C. Coronal sec-
tion through frontal lobes shows hemorrhagic infarc-
tion in the right middle cerebral artery territory.
Much of the hemorrhage is con¬ned to the cortical
regions. The right hemisphere is greatly swollen
compared to the left. (continued on next page) B




C




Central Nervous System 615
D




E

12-6. (Continued) D. Close-up view of the same
infarct shows a sharp distinction between normal and
abnormal white matter underlying the infarct. Note
that the hemorrhage is largely within the gray matter
with a perivascular or petechial appearance. This is
due to gray matter having a ¬ve times greater vascu-
larity than the white matter. E. Histology of this 4- to
5-day-old infarct shows eosinophilic degeneration of
neurons, mild neutrophilic in¬ltration, perivascular
cuf¬ng by mononuclear cells, and several areas of
hemorrhage.




616 Central Nervous System
12-7. A. Well-established infarct of left occipital
lobe shows shrinkage of the involved area. B. Liq-
uefactive necrosis (X) of the cerebellum following
infarction. C. Histology shows liquefactive necrosis
of the cerebral tissue with large numbers of swollen
A
microglial cells ¬‚oating in a ¬‚uid-¬lled stroma.




C
B




Central Nervous System 617
A B




C

12-8. A. Massive subdural hematoma overlies left
cerebral hemisphere. B. View of brain from the top
shows indented left frontal lobe (top left) due to
compression by the subdural hematoma. C. Coronal
section through frontotemporal region shows inden-
tation and left-to-right shift of brain with evidence
of cingulated gyrus herniation. (continued on next
page)




618 Central Nervous System
12-8. (Continued) D. Transected midbrain of the same brain
shows herniation of the left uncus, which shows prominent
notching and some hemorrhagic softening. The midbrain also
shows secondary brainstem (Duret) hemorrhages. Also note the
ragged destruction of the right cerebral peduncle (Kernohan™s
notch) (KN) due to compression of the opposite peduncle
against the free edge of the tentorium. This lesion may lead to
a paradoxical paresis ipsilateral to the side of the mass lesion.
E. Sections through the rostral brain stem showing secondary
Duret hemorrhages due to transtentorial herniation with rup-
ture of penetrating vessels, which are anchored as the brain-
D
stem shifts downward.




E




Central Nervous System 619
A



12-9. Leptomeningitis indicates in¬‚ammation local-
ized to the pia mater/arachnoid mater that contain
cerebrospinal ¬‚uid. A. Purulent basal meningitis
over the pons and the cerebellum due to ascending
spread of infection from the spinal cord region.
B. Typical appearance of generalized purulent
meningitis. The leptomeninges appear clouded,
especially in the sulci, due to abundant purulent
exudate in the subarachnoid space. C. The sub-
arachnoid space is histologically seen to be ¬lled by
closely packed neutrophils. (continued on next
B
page)




C




620 Central Nervous System
D




E

12-9. (Continued) D. Gram stain of in¬‚ammatory
in¬ltrate shows gram-positive diplococci consistent
with Streptococcus pneumoniae. This organism
causes meningitis in older persons and often causes
meningitis in persons with fractured base of skull.
E. Cauda equina syndrome (compression of the
nerves in the lower portion of the spinal canal
below the termination of the cord) came about in
this patient due to organized meningitis. The
meninges appear thickened. The cauda equina his-
tologically showed axonal degeneration and ¬brosis
of many spinal roots.




Central Nervous System 621
B
A




C

12-10. Herpes simplex virus type 1 (HSV-1) encephali-
tis presents as a fulminant infection and often affects
the temporal lobes most severely. A. Softening, discol-
oration, and focal hemorrhages in the medial frontal
lobes bilaterally. B. Coronal section at the level of the
thalamus shows hemorrhagic softening (necrosis) in
the left medial temporal lobe and the right lateral lobe.
C. High-power histologic appearance of intranuclear
inclusions due to HSV-1 infection. (continued on next
page)




622 Central Nervous System
D E




F

12-10. (Continued) D. Immunohistochemical stain
(brown labeling) for HSV-1 antigens labels most
cells in this brain section. E. Electron micrograph
of brain tissue from the case illustrated previously
shows typical herpesvirus particles within the
nucleus of an infected cell. F. Coronal section of
brain from a patient with resolved HSV-1 encephali-
tis shows bilateral extensive damage to the tempo-
ral lobes with much loss of brain substance. This
distribution is typical for HSV-1 infection.




Central Nervous System 623
A B




C

12-11. Cerebral aspergillosis is a complication of an
initial pulmonary Aspergillus infection, which is
more prone to become disseminated in immuno-
compromised individuals. A. Coronal section at
level of hypothalamus shows a large area of hemor-
rhagic necrosis involving the left basal ganglia. A
smaller lesion occupies the left inferior frontal
gyrus. B. Close-up view of both lesions, which have
a distribution unlike that of infarction based on a
vascular distribution. C. Brain of another patient
shows multiple infarct-like lesions due to
aspergillosis. (continued on next page)




624 Central Nervous System
D



12-11. (Continued) D. Close-up view of one of the
brain slices seen in C. E. Hyphae of Aspergillus
within cerebral infarct show acute angle branching
and surrounding necrotic tissue is in¬ltrated by dis-
integrating neutrophils. F. Grocott methenamine sil-
ver stain shows fungal hyphae in¬ltrating into the
arterial media (left).




E




F




Central Nervous System 625
A




B




C

12-12. A. Brain abscess due to Petriellidium boydii infection in a
heart transplant recipient. Hemorrhage is related to a recent neuro-
surgical procedure. B. Appearance of the same brain abscess in a coro-
nal section. C. Whole mount histologic section of the brain abscess.



626 Central Nervous System
A




B

12-13. Arnold“Chiari malformation and associated lesions. A. Spina
bi¬da with meningomyelocele at lumbar level of the spinal cord
showing the ulcerated sac of the meningomyelocele communicating
with the skin surface. B. Dissection of the meningomyelocele shows
that the spinal cord terminates in the sac of the malformation. (con-
tinued on next page)




Central Nervous System 627
C




D




E

12-13. (Continued) C. Histology of the interface between the dermal
and the neural elements of the meningomyelocele in spina bi¬da.
Dermal elements lie on the left and dysplastic spinal cord elements
with reactive gliosis lie on the right. D. Hydromelia of the spinal cord
above the meningomyelocele. The central canal of the spinal cord is
widely dilated. E. Dilated central canal of hydromelia has an intact
ependymal lining. The condition is analogous to hydrocephalus.
(continued on next page)


628 Central Nervous System
12-13. (Continued) F. Cervical spinal cord exposed
from the posterior aspect in Arnold“Chiari malfor-
mation. Due to downward displacement of the
spinal cord, the cervical roots must ascend to reach
the spinal foramina. G. Posterior fossa abnormality
in Arnold“Chiari syndrome. Upper specimen shows
a sagittal section through the brainstem and the
cerebellum of a normal child. Lower specimen
shows a similar section in a patient with the
Arnold“Chiari malformation. Note the elongated
brainstem, fourth ventricle, and herniation of the
posterior cerebellar vermis and caudal brainstem
into the spinal canal. The level of the foramen mag-
F
num is labeled (FM). (continued on next page)




G




Central Nervous System 629
H




I

12-13. (Continued) H. Left specimen is a transverse
section of midbrain from a normal infant. The sam-
ple on the right is a similar section from an infant
with an Arnold“Chiari malformation showing the
“beaked” appearance of the tectum with fusion of
the colliculi and severe stenosis of the aqueduct. I.
Hydrocephalus in a newborn with Arnold“Chiari
malformation showing dilatation of the lateral ven-
tricles and the temporal horns of the lateral ventri-
cles. The septum pellucidum is absent, as it may be
in severe, chronic hydrocephalus.




630 Central Nervous System
A




C
B

12-14. Parkinson disease (PD) is a common neu-
rodegenerative disease, and Parkinsonism (syn-
drome) may have many causes, but most are asso-
ciated with degeneration of the dopaminergic
neurones of the substantia nigra. Dementia and
dysautonomia are due to lesions elsewhere. A. Two
sections of normal midbrain on the left showing
normal substantia nigra (pigmented zones). Two
sections on the right from a patient with PD show
a loss of pigmentation in the areas corresponding to
substantia nigra. B. Substantia nigra in PD showing
loss of density of pigmented nuclei with scattered
macrophages containing pigment. Occasional Lewy
bodies are seen in surviving neurones. The charac-
teristic pathological feature of PD is the presence of
Lewy bodies (alpha-synuclein“containing inclu-
sions) in the cytoplasm of surviving neurones in
areas of neuronal loss. C. Prominent Lewy body in
a neurone with reduced pigment content. The Lewy
body comprises a brightly eosinophilic, amorphous
structure surrounded by a clear halo.



Central Nervous System 631
A




B

12-15. Alzheimer disease (AD) is the most common
cause of neurodegenerative dementia. Morphologic
changes usually begin in the mesial temporal lobe
and then become more generalized. (Memory
de¬cits precede global cognitive problems.) A. Lat-
eral view of the brain in AD. Note that the accen-
tuated sulci secondary to gyral atrophy is most
apparent in the frontal and temporal lobes and is
least apparent in the occipital lobe (left). B. Coro-
nal section of the brain shows ventricular dilatation
and pronounced cortical atrophy, especially in the
region of the Sylvian ¬ssure. (continued on next
page)




632 Central Nervous System
C




D

12-15. (Continued) C. Coronal section (slightly more
posterior than the previous picture) shows marked
atrophy of the temporal lobes. The temporal horns
are dilated, and the anterior hippocampal formation
(H) is greatly shrunken. D. Hematoxylin-eosin-
stained section shows a plaque with an amyloid
core (deeply eosinophilic central portion).
Increased numbers of microglial cells are also evi-
dent. Amyloid angiopathy often accompanies AD.
The amyloid in AD is composed of beta-amyloid, a
form that is unique to AD. (continued on next page)




Central Nervous System 633
E




F

12-15. (Continued) E. Silver stain demonstrates sev-
eral neuritic plaques (NPs) of AD that have a cen-
tral dark brown core composed of amyloid. The
periphery of each plaque bears silver positive neu-
ritic processes. The diagnosis of AD is based on
¬nding increased numbers of NPs for the patient™s
age. F. Multiple neurones are seen to contain neu-
ro¬brillary tangles in their cytoplasm. These tangles
comprise accumulations of tau and MAP2 proteins
and ubiquitin.




634 Central Nervous System
A




B




C

12-16. Amyotrophic lateral sclerosis (ALS) is the most common form
of motor neurone disease, and it affects both upper and lower motor
neurons. It is slightly more common in men, and up to 10% are
familial, usually with an autosomal dominant inheritance. A. Atro-
phy of the interosseous muscles of the hand in ALS. B. Gross appear-
ance of three levels of the spinal cord in ALS showing whitish dis-
coloration of the lateral columns due to degeneration of the
corticospinal tracts. C. Transverse sections of the cervical spinal cord
stained with an immunostain against myelin basic protein shows loss
of myelinated ¬bers in the lateral columns. (continued on next page)


Central Nervous System 635
D




E

12-16. (Continued) D. Spinal cord shows marked
atrophy of the anterior nerve roots (below) com-
pared to the normal posterior (sensory) roots
(above). E. Anterior horn of spinal cord shows sig-
ni¬cant loss of anterior horn cells with reactive
gliosis.




636 Central Nervous System
A B




C

12-17. Multiple sclerosis (MS) shows variable clin-
ical features according to the location of the patho-
logical lesions. The acute lesions are due to an
autoimmune in¬‚ammatory process with myelin
loss. The Epstein“Barr virus may be implicated
in its pathogenesis. Chronic pathology comprises
sharply circumscribed areas of con¬‚uent loss of
myelin with gliosis and partial loss of neurons. A.
Coronal section at the level of the hypothalamus
shows extensive plaque involvement of the basal
ganglia bilaterally and also affecting both internal
capsules. The white and gray matter is also exten-
sively involved. Collapse of the internal capsules
suggests neuronal loss in addition to demyelination.
B. Coronal section at the level of the thalamus and
the lateral geniculate bodies shows multifocal small
plaques (arrows) in the white matter of the periven-
tricular and perithalamic regions. C. Cross-sections
through the optic chiasm showing extensive
involvement by MS plaques. (continued on next
page)




Central Nervous System 637
D




E

12-17. (Continued) D. Whole mount section of thal-
amus and hypothalamus stained by Luxol fast blue-
periodic acid-Schiff stain for myelin shows MS
demyelination plaques sparing the internal capsule.
E. Higher-power view shows the edge of a plaque
on the left, and myelinated ¬bers still stain blue on
the right.


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