|LETTER TO THE EDITOR
|Year : 2019 | Volume
| Issue : 6 | Page : 553-554
Negative images of mycobacteria in cytology
Rashmi Patnayak1, Itishree Chowdhury2
1 Department of Pathology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, Odisha, India
2 Department of Pathology, Capital Hospital, Bhubaneswar, Odisha, India
|Date of Web Publication||17-Oct-2019|
Department of Pathology, Institute of Medical Sciences and SUM Hospital, Bhubaneswar, Odisha
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Patnayak R, Chowdhury I. Negative images of mycobacteria in cytology. Med J DY Patil Vidyapeeth 2019;12:553-4
A 34-year-old male patient presented with bilateral multiple matted cervical lymph nodes and low-grade fever of 1-month duration. He was an immunocompromised (human immunodeficiency virus) patient. Fine-needle aspiration cytology of the cervical lymph node yielded pus-like material.
The air-dried smears were stained with Diff-Quik and Ziehl–Neelsen (ZN) stain and alcohol-fixed smears were stained with Papanicolaou stain. The smears showed scant cellularity. Neither epithelioid cell granulomas nor caseating necrosis was observed in the smears examined. There were neutrophils, lymphocytes, plasma cells, and macrophages in a necrotic background. Negatively stained rod-shaped structures were observed in macrophages and also in the background in Diff-Quik-stained smears [Figure 1]a. In ZN stain, numerous acid-fast bacilli identified [Figure 1]b. The cytological diagnosis given was necrotizing lymphadenitis of Koch's etiology. Mycobacterium avium intracellulare was obtained in culture.
|Figure 1: (a) Negatively stained rod-shaped structures (Diff-Quik stain, ×400). (b) Numerous acid-fast bacilli (ZN stain, ×400)|
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To diagnose mycobacterial infections in cytology, the presence of characteristic granulomatous or purulent host response is required in addition to identification of acid-fast bacilli. This response may be lacking in immunocompromised patients. Hence, a high index of suspicion on the part of the pathologist helps in identification of the organisms.,
Special stains such as ZN and auramine–rhodamine stains demonstrate mycobacteria which are not visualized in routine stains such as Leishman, Giemsa, hematoxylin and eosin, and Gram stain. However, in routinely stained smears, they may appear as negatively stained or as ghost images. Awareness of this finding of negatively stained bacilli is essential as it leads to demonstration of mycobacteria by special techniques, even in the absence of typical cytological features of tuberculous infection.
In immunocompromised patients, the typical cytological features of tuberculosis such as epithelioid granulomas and caseating necrosis may not be present. In contrast, the smears of these patients may show plenty of neutrophils or sheets of histiocytes. Hence, in these cases, mycobacteria may be missed. They should be specifically searched for by means of special stains for mycobacteria. Cytology smears stained by Romanowsky stains may demonstrate negatively stained images in the cytoplasm of histiocytes and in the background., Negatively stained ghost images of mycobacteria or “footprint” give an important clue in such cases. In our case, there were negatively stained images in the Diff-Quik stain. Jannotta and Sidawy had described the presence of mycobacteria by numerous negatively stained images in Diff-Quik-stained cytology smears, in their study of intraoperative cytology of lymph nodes in patients with acquired immunodeficiency syndrome.
This finding should be kept in mind, particularly when the aspirate from an immunocompromised patient is purulent without typical cytological finding of tubercular infection.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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