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Letter to the Editor

Incidental detection of microsporidium spores on Ziehl–Neelson staining done on cervical pap smear

Department of Pathology, AIIMS, Bathinda, Punjab, India
Corresponding author: Gargi Kapatia, Department of Pathology, AIIMS, Bathinda, Punjab, India.
This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

How to cite this article: Khera U, Kapatia G, Rana MK. Incidental detection of microsporidium spores on Ziehl–Neelson staining done on cervical pap smear. CytoJournal 2023;20:9.


Microsporidia are group of spores forming intracellular obligate fungi causing infections particularly in immunocompromised individuals. This case shares our experience with the infection caused by this rare pathogen in cervical pap smear. A 46-year-old postmenopausal women presented with chief complaints of generalized abdominal discomfort and discharge per vaginum. The patient was neither having any history of comorbid conditions nor was immunocompromised. On per speculum examination, cervix showed mild erosions. On per vaginal examination – uterus was anteverted, bilateral fornices were free, and mild discharge was present per vaginum. A conventional cervical pap smear was taken. Cervical pap smear revealed superficial and intermediate squamous epithelial cells, along with parabasal cells admixed with dense neutrophilic inflammatory infiltrate. Few of the squamous epithelial cells show reactive cellular changes in the form of nucleomegaly with overlapping and overcrowding. Epithelioid cell granulomas and multinucleated giant cells also noticed. Tuberculosis was suspected on first go and Ziehl–Neelson (ZN) stain was done. To our surprise, ZN stain highlighted multiple oval acid-fast spores consistent with the morphology of microsporidial spores [Figure 1]. Additional special stains to demonstrate these spores could not be performed as only single smear was received for routine cytological examination. Microbiological correlation was advised from our side; however, the patient was lost to follow-up. We describe the first case of microsporidial granulomatous inflammation on cervical pap smear to the best of our knowledge.

Figure 1:
(a) Epithelioid cell granulomas admixed with acute neutrophilic inflammatory infiltrate in the dirty background (Papanicolaou, ×400), (b) multinucleated giant cells admixed with acute inflammatory infiltrate composed of neutrophils in the dirty background (Ziehl–Neelsen, ×400), (c) epithelioid cell granulomas with acute neutrophilic inflammatory infiltrate (Ziehl–Neelsen, ×400, red arrow), and (d) multiple oval-shaped acid fast spores (Ziehl–Neelsen, ×1000, black arrow).

Cervical pap smear cytology is used primarily to screen women for carcinoma cervix. However, certain infections with microorganisms can also be identified on cervical pap smear cytology. Granulomas on cervical pap smear cytology can be seen in various non-neoplastic and neoplastic conditions. Non-neoplastic or infections conditions associated with granulomatous inflammation include tuberculosis,[1] sarcoidosis,[2] granuloma inguinale,[3] or coccidioidomycosis[3] microsporidia mostly affect immunocompromised hosts. Spores infecting humans are 1–5 µm in length and 1 µm in width.[4] Microsporidial spores show marked morphological variations, and the small and slender forms can resemble bacilli.[5] Mostly, microsporidia affecting humans are able to disseminate. Therefore, if they are found in a single location, other sites in the body should be carefully examined to which they are known to spread. In the examination of ZN-stained smears, these organisms can be overlooked or rarely can be misdiagnosed as acid– fast bacilli of tuberculosis if pathologist is not aware of its peculiar morphological features.

Therefore, it requires a great deal of expertise on the part of cytopathologist to identify these organisms. Other special stains that can be used are PAS, GMS, Calcoflour white stain, acridine orange, masson’s trichome, brown-brenn gram stain, and gram’s chromotrope stain. Hence, we wanted to ascertain the importance of a simple, easy to perform ZN stain for identification of microsporidial spores as an etiology of granulomatous inflammation on cervical pap smear. Identifying these rare pathogens will reduce the chances of misdiagnosis and will hasten the appropriate management of patients with these infections.

Author’s contributions

Dr. Utkarshni Khera took part in evaluation of the case and manuscript drafting. Dr. Gargi Kapatia was involved in final evaluation of the case, manuscript drafting, editing, and revision. Dr. Manjit Kaur Rana was involved in the final evaluation of the case.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.


The authors declare no potential conflicts of interest.


This report does not require approval from the Institutional Review Board.


GMS - Grocott methenamine silver

PAS - Periodic Acid Schiff


To ensure the integrity and highest quality of CytoJournal publications, the review process of this manuscript was conducted under a double-blind model (the authors are blinded for reviewers and vice versa) through automatic online system.


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