| Abstract|| |
Background: Histopathologists encounter strange structures in tissue sections that appear unrelated to tissues, and these artifacts may be misinterpreted and misdiagnosed as pathological lesions. These substances may either be present within the tissues or can get implanted into tissue during biopsy procedure or laboratory handling or processing. Aims: The aim of this study is to observe the microscopic appearance of different abnormal structures like commonly implanted food particles or easily incorporated substances during tissue processing with their probable histological misdiagnosis. Materials and Methods: Certain food particles, suture materials, wood pieces, insects, and filter paper were intentionally introduced in the tissue specimens of uterus and lung. Following routine processing and hematoxylin and eosin staining, the slides were subjected to single-blind study and viewed under light and polarizing microscope. Results: The vivid appearances of these structures lead to histological misdiagnosis. Conclusion: Knowledge and familiarity of these commonly encountered extraneous substances will help to prevent misinterpretation.
Keywords: Artifacts in histopathology, extraneous substances, polarizing microscope
|How to cite this article:|
Shashikala P, Sreevidyalatha G M, Nandyal SS, Umapathy GK. Familiar trespassers in histopathology: An obstacle in diagnosis? A single-blind study. Indian J Pathol Microbiol 2017;60:524-7
|How to cite this URL:|
Shashikala P, Sreevidyalatha G M, Nandyal SS, Umapathy GK. Familiar trespassers in histopathology: An obstacle in diagnosis? A single-blind study. Indian J Pathol Microbiol [serial online] 2017 [cited 2019 Sep 20];60:524-7. Available from: http://www.ijpmonline.org/text.asp?2017/60/4/524/222962
| Introduction|| |
Histopathologists come across various structures in tissue sections which may be misinterpreted and misdiagnosed as pathological lesions. These substances may either be present within the tissues or can get implanted into tissue, during biopsy procedure or during laboratory handling, grossing, or processing. This study was conducted to observe the microscopic appearance of different abnormal structures such as commonly implanted food particles and easily incorporated substances during tissue processing with their probable histological misdiagnosis.
| Materials and Methods|| |
Different extraneous substances that may reach the histopathologist through biopsy tissue were considered in this study. These samples were segregated into three categories. The first category included samples of food particles that may reach pathologist through biopsy tissue. These included chana dal, green gram, rice, groundnut, red chilli seeds, cumin seeds, curry leaves, and coriander leaves. The second category of samples included extraneous substances that may get introduced during surgical removals such as different types of suture materials, namely, vicryl, catgut and silk. The third category included substances that may get incorporated during grossing of the tissue and processing such as filter paper, sponge, wood pieces, and insects.
The food particles considered for the study were partially cooked before inserting them into tissue sections. The study samples were intentionally introduced in the tissue sections of uterus and lung. An incision was made in the fixed tissue sections of myometrium of the uterus and in fixed sections of the lung in some cases, using a scalpel and then, these unfixed extraneous substance was inserted into the incision using a tissue forceps. After 24 h of fixation, these tissues were routinely processed and paraffin-embedded sections of 5 μ thickness were taken and stained with hematoxylin and eosin. A Single-blind study was conducted in which the slides were given to two independent pathologists for microscopic evaluation. They were unaware of the extraneous substances. These slides were mixed with routine slides which were being reported. Later all, the sections were subjected to polarizing microscopy. Results were recorded and tabulated.
| Results|| |
The vivid appearances of these structures lead to histological misdiagnosis in this single-blind study as shown in the table below [Table 1].
|Table 1: Light microscopy of different extraneous materials with their probable misdiagnosis|
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There were certain difficulties encountered during the study. Few sections were difficult to cut and were getting detached from the slides during staining. A new microtome blade was used in such cases, and extra albumin was smeared on the slide to avoid detachment of sections. Thick and fibrous myometrium was replaced with lung tissue for easy incorporation of ants and rice.
Appearance under polarizing microscope
Positive birefringence was observed with all substances included in Category I and Category II except catgut. In Category III, part of the ant which was incorporated in the section and Sponge did not show birefringence [Figure 1].
|Figure 1: (A) Chanadal resembling (B) suture material, (C) greengram resembling (D) columnar epithelium, (E) groundnut resembling (F) adipocytes, (G) chiliseed resembling (H) hydatidcyst, (I) cumin, (J) rice, (K) curry leaf, (L) coriander leaf, (M) vicryl, (N) silk, (O) catgut, (P) ants, (Q) wood, (R) sponge (S) filter paper resembling, (T) anucleatesquames ((A1 C1 E1 G1 and inset in I to S-polarizing-microscopy)|
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| Discussion|| |
An artifact (Latin'ars'-art+'factum'-made) is a feature or phenomenon not usually expected and is caused by an offending external agent or procedure, as an unwanted feature in a microscopic specimen.
These artifacts when encountered by a pathologist in histopathology sections can lead to misdiagnosis and thus hamper appropriate treatment of the patient. It is very important to specifically recognize the microscopic morphology of the external particles or structures to avoid litigation in cases of misdiagnosis.
There are only a handful of research papers available that have discussed causes of developing an artifact in biopsy specimens and a few narrating the importance of adequate recognition of artifacts. This study is unique because it presents the artifacts produced by food particles and other extraneous substances with their probable misdiagnosis which can be an obstacle in diagnosis.
There is no adequate data in literature which enlightens us with the probable causes of all artifacts noticed during microscopic evaluation of biopsy specimens, which possibly get incorporated in tissues during biopsy procedure, during histotechnical processing and staining procedure of sections.
Food particles can be encountered in tissue sections obtained from biopsy or from specimens of lung, periapical region, oral cavity intestine, and perianal region, with or without inflammation and foreign body granuloma. It is important to rule out serious pathological lesions or malignancies, which they simulate.
Exogenous agents or food particles such as pulses and peas get implanted in periapical tissues and may elicit a tissue reaction, referred to as vegetable granuloma or pulse granuloma. Lung involvement is seen in individuals with risk factors such as impaired reflexes, intoxication, anesthesia, or other disturbances of brain function, ryles tube feeding, electroconvulsive therapy as they are prone for aspiration pneumonia. In these cases, pulses and food substances are cooked to a puree or soup form before consumption; hence, when aspiration occurs, cells are liable to get widely disseminated throughout the lung. The indigestible cellulose part of food particles persists as hyaline material and initiate a granulomatous reaction causing severe pulmonary granulomatosis. Histologically, they appear as homogenous eosinophilic material surrounded by acute and chronic inflammatory cells and foreign body giant cells.
The starch powder is a lubricant of surgical gloves and can cause iatrogenic starch granuloma. It can accidentally contaminate biopsy tissues during surgical removal or during specimen processing. Lovas et al. have reported that these starch bodies might resemble epithelial cells. Starch appears as refractile, glassy, polygonal bodies which are periodic acid Schiff-positive and exhibit “Maltese cross” birefringence under polarized microscopy.,
Suture materials that get incorporated in tissues during surgical procedures can present as isolated fragments or complete fibre-bundles cut in transverse, oblique, or longitudinal planes appearing as well-defined polygonal isomorphous tiny structures. In our study, the suture materials such as silk and catgut took eosin stain while vicryl remained unstained giving a lumen-like appearance, similar to study done by Sonal et al. in which majority of them took up eosin stain whereas a few remained unstained giving a lumen-like appearance as formed by the folding of the thin stratified squamous epithelium.,
Polarizing microscopy was useful in identifying most of the extraneous substances. Birefringence of Catgut was difficult to appreciate. Catgut, an absorbable suture is known to be weakly birefringent.
Substances such as filter paper, sponge, wooden cutting board pieces, and insects such as ants may get incorporated into tissues during grossing and laboratory handling. Filter paper resembled eosinophilic anucleate squames of epidermoid cyst.
In few studies, an attempt was made to evaluate the extraneous substances present in tissues sections using polarizing microscopy.,, It has been proven by few authors that the food materials that contain cellulose in their cell walls exhibit positive birefringence which was similar finding in our study.,
| Conclusion|| |
The various extraneous substances and food particles which were introduced or embedded in the biopsy tissues created a diagnostic dilemma to pathologist. Our study brought about familiarity with common artifacts which can be misdiagnosed as pathologic lesions and created awareness of histological appearance of these substances. Polarizing microscopy played a very important role in identifying most of these extraneous substances.
Clinicians and pathologists should consider the occurrence of these materials in biopsies, and additional diagnostic techniques such as polarizing microscopy and special stains could be used for identifying the real nature of extraneous bodies.
The knowledge gained and familiarity will help pathologists to prevent histological misdiagnosis. Further studies involving more structures are needed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Dr. G M Sreevidyalatha
Department of Pathology, SSIMS and RC, NH4 Bypass, Davangere, Karnataka
Source of Support: None, Conflict of Interest: None