2023, Volume 39, Number 1, Page(s) 042-054
Seeds or Parasites? Clinical and Histopathological Features of Seeds and Parasites in the Appendix
Gizem ISSIN1, Fatih DEMIR1, Hasan Aktug SIMSEK2, Diren Vuslat CAGATAY1, Mahir TAYFUR1, Ali KANDEMIR3, Mecdi Gürhan BALCI1
1Department of Pathology, Erzincan Binali Yildirim University, Mengucek Gazi Training and Research Hospital, ERZINCAN, TURKEY
2Eskisehir City Hospital, ESKISEHIR, TURKEY
3Department of Biology, Erzincan Binali Yildirim University, Faculty of Science and Art, ERZINCAN, TURKEY
Keywords: Plant seeds, Enterobius vermicularis, Taenia subspecies, Foreign bodies, Appendicitis, Parasites
Parasites and plant seeds may both be found in appendectomy specimens. Each plant seed has a different appearance and can thus
exhibit wide variations under the microscope. Fragmented seeds may histologically mimic parasites. The differential diagnosis between seeds and
parasites can be challenging in such cases. This study aimed to determine the incidence of parasites, seeds, and foreign bodies in appendectomy
materials and highlight the most characteristic histopathological features associated with these structures.
Material and Method: In this study, pathology slides of 9,480 patients, who underwent appendectomy between 2010 and 2021, were reviewed,
and cases that contained parasites, seeds, or foreign bodies were identified. We reviewed the literature on seeds and parasites in appendectomy
Results: Parasites were observed in 56 (0.6%) cases. Of these cases, 45 had Enterobius vermicularis (80%), and 11 had Taenia subspecies (20%).
Plant seeds were observed in 47 cases (0.5%), and were macroscopically recognizable in 5 of them as olive, lemon, and cherry seeds. Parasites and
seeds were usually observed in the lumen of appendix vermiformis, filled with abundant fecal materials.
Conclusion: Seeds are seen in approximately 0.5% of the appendectomy specimens. Though rarely seen, the fragmented seed appearance may
cause diagnostic difficulties. In this context, the key morphological features of parasites and plant seeds outlined in this study may be helpful in
their differential diagnosis.
Parasitic infections of the gastrointestinal tract are
common; nevertheless, parasites are rarely detected in
appendectomy specimens 1
. The most common parasitic
agent in the appendix is Enterobius vermicularis (EV).
Other parasites, such as Taenia subspecies (Taenia spp.),
Balantidium coli, Entamoeba histolytica, Schistosoma, and
Ascaris lumbricoides, are less common 2,3
. If parasites
are detected in appendectomy materials, stand-alone
application of appendectomy is not sufficient for treatment.
It may be necessary to run additional diagnostic tests and
Foreign bodies, undigested food residues, and plant seeds
may occasionally be seen in appendectomy specimens 4-6. Each plant seed and food particle has a different appearance
and can thus exhibit wide histological variations under
the microscope. Given their rarity, non-expert pathologists
may be unfamiliar with the histopathological features
of such substances. Consequentially, the undigested food
particles and seeds might be misdiagnosed as parasites,
which leads to unnecessary treatment decisions.
In this study, we aimed to determine the incidence of parasites,
plant seeds, and foreign bodies in appendectomy
materials and highlight the most characteristic histopathological
features of the most commonly identified seeds and
parasites to provide sample reference images, which would
be helpful in routine diagnosis.
The pathology departments electronic records were
reviewed to identify the patients that underwent
appendectomy between January 2010 and January 2021.
The hematoxylin and eosin (H&E)-stained slides of all
cases were re-examined. Cases in which parasites, foreign
bodies, and seeds were found were included in this study.
The demographic data and histopathological features of the
cases were documented.
The undigested materials in the appendectomy specimens
were evaluated together with the botanist (A.K.). Cases with
intact plant structures such as seed coat, endosperm, and
embryo sections were categorized as the cases containing
seeds. However, cases containing only fragmented or semidigested plant structures were categorized as the cases
containing food residues. The types of the seeds observed
in these cases were identified by comparing them with
reference images of seeds and plants in the catalogues 5-7.
We reviewed the literature to identify studies about parasites
observed in appendectomy specimens. Methods, flow
chart of literature review, inclusion and exclusion criteria
were given in Appendix 1. The relevant studies are compiled
in Table I (8-50). Also, we reviewed the literature
to identify studies about seed observed in appendectomy
specimens without any date or language restriction and
compiled the relevant studies in Table II 6,7,51-62.
Click Here to Zoom
|Appendix 1: Flow diagram of literature review
* We conducted a literature review using PubMed, and Google Scholar database to identify studies published with full text in English about
parasites in appendectomy specimens, which were published between January 2000- January 2020. Search was conducted using the following
keywords: (parasites in appendix vermiformis), (vermiform appendix parasite infestation), (parasites in appendectomy).
This study was approved by the Local Ethics Committee
(decision no: 07/15, decision date: 24.05.2021) and
conducted in accordance with the principles set forth in the
Declaration of Helsinki.
Data obtained as a result of the study were analyzed
statistically. Continuous variables were expressed as mean
± standard deviation (SD) values, and categorical variables
were expressed as numbers (n) or percentage (%) values
The H&E slides of 9,480 appendectomy specimens were reevaluated.
Adult or ova of parasites were observed in 56
(0.6%) cases, of whom 37 were female and 19 were male.
The male-to-female ratio was 1:1.9, and the mean age
was 23 years (2-56 years). EV was seen in 45, and Taenia spp. were seen in 11 cases. The mean and median ages of
the patients with EV and Taenia spp. were 19-14 years
and 40-45 years, respectively. All patients with parasitic
infestation presented with right lower quadrant pain. The
ultrasonographic findings were compatible with acute
appendicitis in 41 patients and suspected acute appendicitis
in 15 patients. The mean diameter of the appendectomy
specimens was 0.7 cm (range, 0.4-1 cm). In 32 cases, the
appendix lumen was filled with feces and enlarged. Active
inflammation was observed in 16 cases. Three of these cases
also had perforation. In 40 cases, there was no histological
evidence of appendicitis. The demographic data and
histopathological features of the cases are summarized in
In cases with EV, 1 to 10 adult forms were seen in the
appendix lumens, which were 2 mm to 6 mm x 0.2 mm to 0.4
mm in size, and in which cuticle structures, gastrointestinal
or reproductive organs, and lateral ales could be detected
on the outer parts. Additionally, a D-shaped egg form was
observed in the reproductive system of the female forms.
In three of the cases with Taenia, adult forms with gravid
proglottid were observed in the appendix lumen, whereas
in the other eight cases only eggs form were observed.
Images of some cases with EV and Taenia are given in
Figure 1 and Figure 2.
Click Here to Zoom
|Figure 1: Cross-section of Enterobius vermicularis (EV) in the appendix lumen (A; H&E stain, ×40), adult EV with a thick cuticle,
lateral alae, and visible organs (B; composite photograph of H&E stain ×100, gastrointestinal organs; black arrow); longitudinal section
of the uterine reproductive system of female EV; it is filled with multiple D-shaped ova (C; H&E stain, x400) and adult EV at higher
magnification (D; bilateral spikes (alae); red arrows, the cuticle; blue arrow, reproductive organ; pink arrow, gastrointestinal organ; green
Click Here to Zoom
|Figure 2: Cross-section of the adult Taenia spp. in the appendix lumen (A; composite photograph of H&E, ×100), a section of the adult
Taenia spp. at higher magnification (B; thick outer tegument with microvillus; red arrow, calcareous corpuscles; green arrow, smooth
muscle; blue arrow H&E stain, ×100), and Taenia ova in in the appendix lumen; spherical brown structures and a large round eosinophilic
center (orange arrow) encircled by brown rings (black arrow) (C; H&E stain, ×400)
Plant seeds were detected in 47 appendectomy specimens.
Of the 47 cases with seeds, 21 were female, and 26 were male.
The mean age of these cases was 26 years (median; 24, range;
15-53 years). Seeds were detected during macroscopic examination in five cases: olive seed in one case, lemon
seed in two cases, and cherry seed in the remaining two
cases (Figure 3). In the remaining 42 cases, the seeds were
detected during the histopathological examination. Active
inflammation was present in 35 cases, whereas no evidence
of inflammation was observed in the other 12 cases.
Click Here to Zoom
|Figure 3: Gross appearance of appendectomy specimens: Lemon seed surrounded by fecaloid in the proximal part of appendix lumen
(A), Non specified seed fragments in fecaloid (B), appendix lumen obstructed by cherry pip surrounded with fecaloid (C), Lemon seed
in the proximal portion of the appendix (D)
The seed-containing cases were evaluated under the
guidance of a botanist. Consequentially, it was thought
that the seeds in these cases might pertain to grasses such
as tomato, pepper, kiwi, apple, lentil, and oat. It could
not be possible to determine the origin of the seeds in all
cases. Examples of basic anatomical structures of the seeds,
i.e., seed coat located in the outer part of the nucleus,
endosperm region that surrounds the embryo and provides
nutrition, embryo structures, and convoluted cereal parts
similar to parasites, are presented in Figure 4.
Click Here to Zoom
|Figure 4: Cross-section of seeds in in the appendix lumen; the seed coat (Sc); red arrow, endosperm (End), and embryo (Emb); green
arrow (A, B and C; H&E stain, x100), partly digested seed (D; H&E stain, x200), digested plant-seed fragment with empty endosperm
region (E; x40), partly digested plant seed, endosperm filled with starch and fat (F; H&E stain, x100) and the endosperm region containing
various-sized bright pink-red colored spherules (Ag:aleurone grains); orange arrow (G; H&E stain, x200 and H, H&E stain, x400).
Convoluted, Small grain fragments; thick, the outer grain layer (Ogl: the outermost layer of the endosperm); yellow arrow (H, I, and J;
H&E stain, x400).
Foreign bodies were detected in two cases. There was no
history of swallowing an object in these two cases. Both
patients, 25 and 32 years old, presented with right lower
abdominal pain lasting for 1-2 days. The white blood
cell count was 10x109/L and 9.5x109/L, respectively. In
the USG (ultrasonography) examination, the diameters
of the appendix lumens were increased; thus, they were
interpreted as acute appendicitis. No finding indicated
a foreign body in the abdominal X-ray examinations. A
plastic T-shaped structure was observed within the fecalith
during the macroscopic examination in one of the cases.
In contrast, transparent white small tube-like foreign
body structures were observed during histopathological
examination in the other case (Figure 5).
Click Here to Zoom
|Figure 5: Transparent tube-like foreign body structure in fecaloid (A; H&E stain, x100), under polarized light (B)
Parasites, seeds, and foreign bodies are rarely seen in appendectomy
specimens. The results of the literature review
and Figure 6
) revealed that the prevalence of parasites
in appendectomy specimens varied immensely between
studies (8-50). The highest prevalence was reported
in a study from Libya and the lowest prevalence was reported from Iran, with 68.6% and 0.22%, respectively 38,42
The prevalence ranged between 0.33% and 9.8% in studies
from Turkey 8,49
. In our study, parasites were observed
in 0.6% (56/9.480) of the appendectomy specimens. Some
studies suggested that prevalence could be associated with
the countrys income level, developmental level, and hygiene
. However, since the prevalence is
affected by many factors (the experience of the researcher, number of pieces taken during macroscopic sampling,
the age range of the population, etc.), we believe that welldesigned
prospective studies are required to address the association
Click Here to Zoom
|Figure 6: World map; presenting prevalence of parasites in appendectomy specimens by countries.
* This map was created in Excel format with the data of the studies in Table-1. Its color is based on the study in which the highest prevalence
of that country was reported. The data and the reference numbers of the studies were added to the map with photoshop.
The most common parasitic agent in the appendix has been
reported as EV, while Tenia was the second most common
in several studies, as in our series 15,19,22,26,37. Other
parasitic agents such as Entamoeba histolytica, Balantidium
coli, Entamoeba histolytica, Schistosoma, and Ascaris lumbricoides have been indicated in a few studies 2, though
none of these were observed in the current study.
In our study, there was a significant difference in patient
age between EV and Tenia spp.; the mean and median ages
were 19-14 years for EV and 40-45 years for Tenia spp. EV
infection tended to occur at a younger age than Tenia spp.,
consistent with previous studies 16,44.
Patients with parasite often presented with appendicitislike
symptoms such as right lower quadrant pain,
vomiting, and loss of appetite in our study. However,
appendicitis findings were observed in only 28% of cases.
Furthermore, there was no significant correlation between
the presence of appendicitis and the parasitic agent type.
The literature review showed that the rates of inflammation
accompanying parasitic infestation reported in different
studies varied greatly, between 3% and 100% 44,45.
The fact that inflammation is not observed in every case
raises to question of whether the presence of parasites
in the appendix is coincidental or a factor that triggers
inflammation. It has been reported that the parasites that
involve the mucosa or invade the lamina propria may
trigger inflammation 1,44. However, the relationship
between parasites and ova found in the appendiceal lumen
and the development of appendicitis-like symptoms has not
yet been fully elucidated. As with foreign bodies, parasites
in the appendiceal lumen can induce fecal concretion.
Grimes et al. suggested that the presence of fecaliths could
lead to abdominal pain without inflammation 64. In the
light of this information, appendicitis-like symptoms in the
cases with parasites may be related to the increased feces
concentration and the development of fecaliths.
Foreign bodies are also rarely encountered in appendectomy
specimens 4. Most undigested foreign bodies pass through
the gastrointestinal system and are excreted without any
complication. However, materials with sharp and thin ends
may cause perforation of the appendix. On the other hand,
blunt-ended foreign bodies may not pass into the colon
after entering the appendix 4. Various materials including
retained shotgun pellets, teeth, mercury, eggshells, and
gallstones have been detected in the appendix 4. Most of
these materials are radiopaque; thus, they can be detected
in preoperative radiographic evaluation 4. As is the case
with foreign bodies, large seeds, such as those of olives,
cherries, and lemons pips, cannot be redirected to the
colon after they enter the appendiceal lumen and may thus
cause appendicitis by obstructing the appendiceal lumen.
Tiny seeds are usually determined incidentally during
The literature review results have indicated that most studies
on this subject were carried out in the early nineteenth
century 51-57. In those years, it was thought that seeds
played an important role in developing appendicitis 65.
In the following years, relatively few studies addressed the
seeds, which may be attributed to the fact that the observation
of seeds in the appendix lumen did not change the
treatment plan or follow-up approaches, and thus that the
studies aimed at such findings did not receive enough attention
from researchers for publication purposes. To our
best knowledge, only 63 cases have been described in the
literature to date 6,7,51-62. The details of these cases are
summarized in Table II. The highest incidence was reported
in the study of Grillo et al., in which complete and fragmented
seed parts were found in 13 (2.2%) of the 588 appendicectomy
specimens 7. In this study, we determined
seeds in 47 (0.5%) of the cases. It was thought that the seeds
might pertain to plants such as tomato, pepper, kiwi, apple,
lentil, and oat, in addition to olive, lemon, and cherry. The
mean age of the patients was 26 years and the seeds were
frequently observed in young adults (median age; 24 years).
Only 3 patients were younger than 16 years.
Fruits, vegetables, and undigested food particles can be seen
in the histological or cytological examination of surgical
pathology specimens, and some have been documented in
the literature as potential mimickers of clinically significant
findings 66,67. In the gastrointestinal tract, seeds that can
adhere to the intestinal mucosa with the glycoprotein-rich
villi available on their surfaces may be mistakenly identified
as parasites due to their complex and unfamiliar histological
appearance, leading to a misdiagnosis 68. Knowledge of
the morphological features of such substances is crucial
to distinguish them from parasites and drug residues
which otherwise would require additional treatment.
Routine pathology practices include differential analysis
of the food residues from the structures they can mimic.
However, specific seed type identification may be necessary
for forensic pathology practices, such as determining the
victims last meal 69.
Seeds are multifaceted so that they can exhibit wide variations
under the microscope. In this context, seed fragments
may lead to the suspicion of the presence of helminths, such
as Anisakis simplex 5. Non-expert pathologists may misidentify
seed structures as unusual parasitic agents. Grillo
et al. reported that three cases whose specimens included
seeds were referred by the pathologists who considered
that the seeds could be some un-identified/unrecognized
worm 7. We also observed that some seed photographs
were mistakenly published as parasites in the literature 35,39,70.
The mature seed comprises three parts: seed coat, embryo,
and endosperm structures 5,6. However, the thickness, the
color, and the shape of these structures may differ between
species 7. The outer covering of a seed is called the seed coat.
Seed coats help protect the embryo from external factors.
The endosperm contains bright pink-red colored starch
and fat globules in various sizes that surround and nourish
the embryo with one or two cotyledons 6,7. Fragmentedsemi-
digested seed structure, particularly curly particles of
cereals, may raise suspicion of parasites 5. Parasites are
usually smaller in size than seeds. Females of EVs are often
8-13 mm long, and the males 2-5 mm long. There is a thick
cuticle on the outside and lateral alae that protrude like
spines on the surface. Gastrointestinal and genitourinary
organs could be observed. In the reproductive organs of
females, 50-60 μm by 20-30 μm D-shaped eggs can be
observed 71. Taenia spp., generally 2-12 mm in length,
are rarely observed in appendectomy specimens 2,3.
In most cases, the egg form is seen in the lumen. Taenia
egg, which has a spherical shape, is 30-40 μm in diameter.
Depending on the level of the slice, the egg may appear in
different specimens as spherical brown structures or large
round eosinophilic centers encircled by brown rings. Adult
worms of Taenia have many proglottids (1000 to 2000).
Mature proglottids each have genital organs consisting of
about 300 to 400 testes and a vaginal sphincter 71.
Parasites, foreign bodies, and plant seeds are rarely found
in the appendix, and if present, they are usually detected
incidentally during the histopathological examinations
of the appendectomy specimens. Fragmented seeds can
exhibit wide variations under the microscope, and their
histopathological images can mimic parasites. In such
cases, assessing the above-mentioned histopathological
features will be beneficial for differential diagnosis between
parasites and seeds.
Conflict of Interest
The author(s) declared no potential conflicts of interest with respect
to the research, authorship, and/or publication of this article.
The author(s) received no financial support for this article's research,
authorship, and/or publication.
Concept: GI, Design: GI, FD, HAS, Data collection or processing:
GI, FD, HAS, DVC, MT, AK, MGB, Analysis or Interpretation: GI,
Literature search: GI, FD, Writing: GI, Approval: GI, FD, HAS,
DVC, MT, AK, MGB.
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