Soft Tissue Cysticercosis
Diagnosis by Fine-Needle Aspiration
IGNATIUS T. M. KUNG, M.R.C.PATH., DICK LEE, C.R.C.P. (C), AND HIP CHO YU, F.R.C.S.(EDIN)
Taenia solium infection is endemic in Asia and cysticercosis is
not uncommon. The authors report a case of cysticercosis diagnosed by fine needle aspiration using a cell block. The authors
believe it to be the first such case so diagnosed. (Key words:
Cysticercosis; Fine needle aspiration) Am J Clin Pathol 1989;92:
834-835
FINE NEEDLE ASPIRATION (FNA) is now very popular and can be applied to almost any palpable lesion.
We report a case of cysticercosis diagnosed by FNA. While
FNA diagnosis of hydatid disease is well documented, 4 as
far as we are aware, this is the first report in literature of
FNA diagnosis of cysticercosis.
Report of a Case
The patient is a 51-year-old Chinese woman who noticed a nodule
on the left side of the neck for two weeks. On physical examination, the
lesion was a 1 cm well-defined mobile nodule in the posterior triangle,
partly covered by the sternomastoid muscle. FNA was done by the pathologist (D.L.). After return of the FNA diagnosis, the patient was interviewed and examined again. Although she resided in Hong Kong, she
had visited the rural areas of mainland China several times during the
previous two years. She had never eaten any raw or undercooked pork.
There were no symptoms or signs of neurologic or eye disease. No further
nodules were found on physical examination. Investigations showed no
peripheral blood eosinophilia, and no parasitic ova or proglottids in the
stool. Chest radiograph, electrocardiogram, and computed tomography
of the brain were all normal.
Material and Methods
FNA was performed using a 10 mL syringe loaded on
a Cameco syringe holder. A 21-gauge needle was used.
The aspirate yielded 1 mL of clear fluid. Smears were
prepared using the rehydration technique and were stained
with hematoxylin and eosin (H & E).1 The residual material and fluid were fixed in 7.5% buffered formalin, and
a cell block was prepared.3 Paraffin sections 5 ^m thick
were stained with H & E.
Received February 14, 1989; received revised manuscript and accepted
for publication May 10, 1989.
Address reprint requests to Dr. Lee: Laboratory, Royal Columbian
Hospital, New Westminster, British Columbia, V3L 3W7 Canada.
Institute of Pathology and ENT Unit, Queen Elizabeth
Hospital, Hong Kong; and Laboratory, Royal Columbian
Hospital, British Columbia, Canada
Results
The smears were acellular. The cell block paraffin sections, on the other hand, showed the wall of a cysticercus
of Taenia solium. The wall was 100 to 200 jum thick and
was raised into dome-shaped elevations (Fig. 1). The tegumental lining was about 5 ^m thick and had microvilli
projecting from the surface (Fig. 2). Beneath the tegument
were muscle fibers stained red with Masson's trichrome
(Fig. 1). The tegument and muscle layer were supported
by loose edematous stroma in which were small dark cells.
A small fragment of dense fibrous tissue, probably of host
origin, also was included. No scolex or hooklets were
identified, even in Ziehl-Neelsen stained sections.
Discussion
Cysticercosis is infection by the larval stage of the tapeworm Taenia solium. Infection by this parasite is common
in parts of Asia.5 Humans are the definitive host of T.
solium. The pig is the intermediate host, in which the
larval cysticercus stage develops. Humans acquire the infection through consumption of undercooked pork harboring the larva, which develop to adults in the small
intestine. Cysticercosis occurs when a human acts as the
intermediate host commonly from ingestion of food or
water contaminated with eggs or proglottids of the parasite
or, rarely, through internal autoinfection as a consequence
of regurgitation of proglottids into the stomach. The organs and tissues commonly involved are subcutaneous
tissue, brain, skeletal muscle, liver, lungs and eyes.
While infection by the adult worm is rare in Hong
Kong, cysticercosis is occasionally seen. Most of the patients come either from mainland China or make visits
to areas where hygiene is poor. In our experience, most
of the cases present with solitary nodules in the subcutaneous region. The nodules usually are surgically removed, and the diagnosis is made on the excised specimen.
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SINGLE CASE REPORTS
FIG. 1 (upper). The wall of the cysticercus
featuring a thin, refractile tegument raised
into dome-shaped projections, a layer of
muscle fibers, and an edematous stroma
with small, dark, round cells. Masson's trichrome (X350).
FIG. 2 (lower). A higher magnification of
the tegument to show the microvilli. Hematoxylin and eosin (X850).
*
This is our first diagnosis based on a fine needle aspirate.
Although FNA diagnosis of hydatid disease is well documented, 4 to our knowledge this is also the first report of
FNA diagnosis of cysticercosis in the English literature.
In our Institute, cell blocks are a routine for FNA.2 In
this present case, diagnosis was entirely based on histologic
study of the cell block paraffin sections. The morphology
of the cysticercus was identical to that described in detail
by Sparks and colleagues.5 It was regrettable that no tissue
was available for cytologic study. Nevertheless, we did
have a cell block that allowed us to make a diagnosis with
confidence. This case also reinforced the fact that although
the aspirate may appear clear and acellular, all of the material should be examined under the microscope. We
found cell blocks a convenient way of achieving this aim.
With the popularity of international travel and immigration, it is expected that there will be more cysticercosis
cases, even in developed countries. It is also expected that
$
&
the cytopathologist will see more of these cases as FNA
is employed more and more liberally as a diagnostic tool.
Acknowledgment. The authors thank Emily Chan for her secretarial
assistance.
References
1. Chan JKC, Kung 1TM. Rehydration of air-dried smear with normal
saline: Application infine-needleaspiration cytologic examination.
Am J Clin Pathol 1988;89:30-34
2. Kung ITM, Yuen RWS. Fine needle aspiration of the thyroid: Distinction between colloid nodules and follicular neoplasms using
cell blocks and 21-gauge needles. Acta Cytol 1989;33:53-60
3. Kung ITM, Yuen RWS, Chan JKC. Optimal formalin fixation and
processing schedule of cell blocks from fine needle aspirates. Pathology (in press).
4. Koss LG, Woyke S, Olszewski W. Aspiration biopsy: Cytologic interpretation and histologic bases. New York: Igaku-Shoin,
1984;355-357
5. Sparks AK, Neafie RC, Connor DH. Cysticercosis. In: Binford CH,
Connor DH, eds. Pathology of tropical and extraordinary diseases.
Vol. 2. Washington DC: Armed Forces Institute of Pathology,
1976;539-543