Cysts that Still Persist: A Case Series of Cysticercosis on Histopathological Evaluation
Flora D LOBO, Kudurugundi Basavaraju VATSALA, Deepa Adiga A S, Sharada RAI
Department of Pathology, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, KARNATAKA, INDIA
Keywords: Cysticercosis, Neurocysticercosis, T. solium, Cystode, Pork
Cysticercus is the infective larval form of the cystode T. solium that causes cysticercosis. It is has been declared as one of the neglected endemic
zoonoses by the WHO. Poor sanitation, and consumption of undercooked infected pork and raw vegetables contaminated by human feces are
the potential sources. Cysticercosis can affect various organs. India is one of the endemic countries where the parasite is prevalent in many
states. This study aimed to analyze and report cases of cysticercosis based on the histopathological diagnosis. This is a retrospective study that
included cases which had been reported as cysticercosis on histopathology from 2010 to 2018 at a tertiary care hospital. The clinical presentation
of these cases along with macroscopic and microscopic features were reviewed. There were six cases of cysticercosis that were diagnosed on
histopathology during the study period. Among them, two cases were intramuscular lesions, three were subcutaneous, and one case was an
intraventricular lesion in the brain. Three of the cases presented as cystic lesions. On histopathological evaluation, cysts were identified in four
cases on macroscopy. Microscopically, the cross section of the cysticercus was seen in all six cases with associated inflammatory change. To
conclude, cysticercosis can clinically present as a benign neoplastic or an inflammatory lesion. Microscopic findings dictate the diagnosis of
cysticercosis, although histopathological evaluation is not common.
Cysticercosis is a zoonotic disease caused by the larval
form, Cysticercus cellulose (C. cellulose) of the cystode
Taenia Solium (T. solium). It was added to the list of
neglected tropical diseases by the WHO in 2010. Taeniasis
is the intestinal infection caused by the adult tapeworm T.
solium, and is the only subspecies that has major impact
on humans 1
. Poor personal hygiene, lack of basic
sanitation, free roaming pigs, consuming contaminated
food and undercooked infected pork are the routes of its
. The ingested egg evolves into a cysticercus and
can disseminate to involve various sites 3
. We report six
cases of cysticercosis that presented at various anatomical
A middle-aged female presented with a swelling in
right arm. Clinically, it was a subcutaneous cystic lesion and
was excised. Grossly, the specimen was a small translucent
cyst. Microscopic examination revealed the cross section
of a larva with evaginated scolex and body segment. There
was dense inflammatory infiltrate composed of eosinophils,
lymphocytes and histiocytes surrounding the larva.
Case 2: A 60-year-old woman presented with a cystic
mass at the back of the neck for about six months. A cut
opened, unilocular cyst measuring 1 cm in diameter was
received for histopathological evaluation. Microscopically,
cysticercus along with a chronic inflammatory infiltrate in
the surrounding fibromuscular tissue was identified.
Case 3: An 8-year-old girl presented with a nodular
swelling in the left arm and received a clinical diagnosis
of lipoma. Macroscopically, a cyst filled with serous fluid
measuring 1 cm in diameter was identified along with
fibrofatty tissue bits. Sections from the cyst wall revealed the
larva cysticercus. The fibroadipose tissue showed multiple
palisading granuloma with a dense chronic inflammatory
Case 4: A 21-year-old lady presented with a nodule in her
eyelid that was clinically suspected to be a chalazion. Excision
biopsy from the nodule was sent for histopathologic
examination. Macroscopically, a small, pale white nodular
tissue was identified. Microscopically, a cross section of
cysticercus with three different layers was seen. An outer
eosinophilic corrugated cuticular layer that had microvilli
with underlying bundles of muscle fibres, a middle cellular layer having small dark nuclei arranged evenly, and an
innermost reticular layer consisting of loose fibrils, excretory
canaliculi, and calcareous corpuscles were noted (Figure
1A, B). A dense chronic inflammatory infiltrate was seen
surrounding the parasite.
Click Here to Zoom
|Figure 1: A) Cross
section of the
cysticercus, * suckers,
^^ coelomic cavity
B) Three distinctive
layers of the cysticercus:
*Outer cuticular layer,
** middle cellular layer,
and *** innermost
reticular layer (H&E;
Case 5: A 13-year-old school going girl was found to
have a right lateral ventricular lesion, when evaluated for
the clinical diagnosis of central nervous system (CNS)
tuberculosis. Four linear friable pale white tissue bits
were received for histopathological examination. The
sections revealed cysticercus, calcified bodies, areas of
gliosis and eosinophilic infiltrate. It was diagnosed as
Case 6: A 33-year-old man presented to the orthopaedic
department with complaint of swelling in the right arm for
three months. On radiological investigation, a diagnosis
of cysticercosis in the biceps muscle was rendered.
Macroscopically, a cut, collapsed, white, membranous
cystic structure attached to the muscular tissue was
seen. On microscopy, the cysticercus larva was seen with
an intramuscular extension of the cyst that was lined
by a palisading histiocytic aggregate and foreign body
granulomatous reaction. Dense mixed inflammatory
infiltrate surrounded the cyst (Figure 2A-D).
Click Here to Zoom
|Figure 2: A) Chronic
inflammation in the
B) Cyst wall lined by
cells (H&E; x40).
C) Cyst wall showing
cells (H&E; x40).
D)* Hooklet (H&E;
The clinicopathological findings are summarized in Table I.
Cysticercosis is mostly seen in those individuals who are
closely associated with subsistence farming. It is common
in Africa, Asia and Latin America 1
. In our retrospective
study, we were unable to retrieve information regarding
the occupational and socioeconomic background of the patients. The case range was from an 8-year-old girl to a
60-year-old lady, and the disease affected both genders.
The infective cysticercus gets lodged at various tissues
and presents as cystic mass lesions with associated clinical
manifestations depending on location. Neurocysticercosis
presents with the most alarming symptoms. According to
the literature, the larva may persist in the CNS for long
time, protected from the blood-brain barrier due to its
active immune evasion mechanism, and may also elicit
inflammatory changes in the surrounding tissue 4-7. In
the CNS, cysts are most commonly found in the fourth
ventricle, followed by the third ventricle, with the lateral
ventricles being the least commonly involved 4,8. Our
case of neurocysticercosis was a young girl with clinical
suspicion of tuberculosis and had a lesion in the right lateral
ventricle. Microscopically the host immune response was
evident in the surrounding tissue.
The severity of nonneuronal cysticercosis is less on human
health. Subcutaneous cysticercosis appears as painless,
small, mobile nodules that are most commonly located in
the arms or chest. The nodules may become swollen, tender,
and inflamed which may gradually disappear. Subcutaneous
cysticercosis is very common in Asia and Africa but rare in
Latin America 4,9. In our study, three of the reported cases
were subcutaneous lesions in the arm, back of the neck and
eyelid. Based on the location, chalazion and lipoma were
the provisional clinical diagnoses, respectively.
Muscular cysticercosis is frequently associated with
neurocysticercosis and appears as an incidental radiological
finding in the form of dot-shaped or ellipsoidal calcifications
following the muscle bundles in the thighs or arms 4.
Dixon reported 75% of patients with neurocysticercosis to have muscular calcifications after several years of
radiographic follow-up 4,10. We have reported one case of
intramuscular cysticercosis in the biceps but the CNS status
of the patient was not followed up.
Macroscopically, the cysts are uniform, round or oval
vesicles measuring a few millimeters to 1-2 centimeter in
size. When the cysts are viable, they have a translucent
membrane, through which scolices can be visualized.
However, when they start degenerating, the fluid in the cyst becomes more opaque and may undergo calcification 4. In
our case series, we identified intact small cysts in only two
cases while in the rest of the cases it was sent after being cut
opened by the operating surgeons. Microscopically all cases
have shown the cross section of the parasite with variable
host immune responses in the form of dense inflammation,
foreign body granulomatous reaction, palisading histiocytic
reactions and additionally gliosis as witnessed in the brain
tissue in neurocysticercosis cases.
Among the three subspecies of taenia, T. solium is most
commonly associated with neurocysticercosis 11,12. Histomorphologically,
there are few significant differentiating
features to classify these subspecies. The most easily recognizable
feature is that C. cellulosae can have 22-32 small and
large hooklets, whereas C. bovis (the larval form of T. saginata)
can have none and C. viscerotropica (larval form of T.
asiatica) will have only rudimentary hooks 13,14.
To conclude, in this era of advanced molecular technologies
to diagnose and manage much more complicated diseases,
certain preventable non-neoplastic, zoonotic diseases
that are prevalent in many parts of the world deserve
equal attention. With the available epidemiological data,
cysticercosis is still a major health burden and cannot be
underemphasized. The disease can manifest as an indolent,
cystic lesion to a complicated CNS lesion. Although
visualization of the parasite on histopathological evaluation
is the more accurate diagnostic test, availability of less
invasive and rapid diagnostic procedures saves time. India
being one of the endemic countries of cysticercosis,
there is ample opportunity for the investigators to learn
extensively the biological nature of the parasite, the various
manifestations of the disease, and its early diagnosis and
management. A combined and targeted effort from the
health, education and animal husbandry departments is
required to educate and bring awareness to prevent the
infection and its associated complications among the
identified at-risk geographic population.
This is a retrospective study and only those cases that
have been evaluated on histopathology were included.
Most of the cysticercosis cases in clinical practice are
diagnosed radiologically and might not be subjected to
histopathological confirmation. Hence, the number of
cysticercosis cases reported in this study may not represent
the actual burden of the disease.
CONFLICT of INTEREST
The authors declare no conflict of interest.
Concept: FDL, Design: FDL, KBV, SR, Data collection or
processing: FDL, KBV, DAAS, Analysis or Interpretation:
FDL, KBV, DAAS, SR, Literature search: KBV, DAAS,
Writing: FDL, KBV, DAAS, Approval: FD, KBV, DAAS,
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