**Author details**

*Sarcoidosis and Granulomatosis - Diagnosis and Management*

confirm mycobacteriosis was in culture [10].

diseases appears to have an uncertain etiology.

also be useful, but not for the detection, but for the identification of fungi found in traditionally stained slides. Real-time PCR can be performed on paraffin sections for tuberculosis diagnostics; the specificity of this method is 99%; however, the sensitivity amounts to only 65%. Nevertheless, when the same method is used to detect mycobacteria tuberculosis in the cerebrospinal fluid, urine, or bronchoalveolar lavage, the sensitivity is more than 90%. Thus, this technique is useful and confirms the diagnosis if mycobacteria are detected, but PCR does not exclude the tuberculosis diagnosis if the result is negative. In addition, it does not allow detecting non-tuberculous mycobacteria. According to Aubry, the cultural study remains the "gold standard" for non-tuberculous mycobacteriosis diagnostics, and, according to their research, indicates that in more than 75% of cases, the only method to

The etiological factor remains unclear in 30–40% of infectious granulomatosis even in leading US university clinics despite a complete histological evaluation of lung tissue slides, as well as correlations with clinical, microbiological, and serological data. In this regard, the question of diagnostic significance of these diseases arises. Ulbright and Katzenstein propose that such cases represent infectious granulomas in which the microorganism was destroyed and/or removed by means of the developed inflammatory process [24]. A retrospective analysis of necrotizing granulomas showed that patients who did not receive further specific therapy were still alive and did not demonstrate any clinical symptoms. The same hypothesis is confirmed by Aubry who notes that even if new foci appear in these patients, poor outcomes were not detected [10]. It can be recommended to pathologists to give a descriptive histological conclusion indicating the presence/absence of necrosis, the absence of detected microorganisms: "The disease etiology is most likely to be

infectious, special stains for the microorganism detection are negative."

When a granulomatous disease is suspected and lung resection is performed, it is necessary to save some specimen tissue unfixed for possible cultural study, and use the quick freeze method at -70°С for subsequent DNA and RNA analyses, if available. In the differential diagnosis of granulomatous diseases, first of all, one should determine whether the granuloma is infectious, or there are signs of other diseases, including Wegener's granulomatosis. If a specific diagnosis is excluded, it is crucial to perform special stains for microorganism detection, it is preferable to stain sections from at least two blocks, while making sure that necrosis foci are present in the material. If the microorganism detection is not possible at the first glance, we recommend evaluating the slides again at a higher magnification, and also using an additional block for staining. When negative result is received, but clinical data are in favor of tuberculosis or other infections, PCR is suggested. Additional cultural and serological studies, which would be able to exclude the infectious process, should be performed in case of another negative result obtained. Nevertheless, according to this algorithm results, a certain part of granulomatous

In conclusion, we would like to emphasize that the differential diagnosis of granulomatous pulmonary diseases is not so easy for pathologists. To exclude or prove the infectious disease, the pathologist should carefully examinate special stained specimens. Noninfectious granulomatous lung disease should be proved, taking into consideration both clinical and radiological data. Finally, from the pathologic point of view, there are the situations for which a specific diagnosis cannot be made. Multidisciplinary approach sometimes is recommended for decision-making.

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Maria V. Samsonova1 \* and Andrey L. Chernyaev2

1 Department of Pathology of Federal State Budgetary Institution, Pulmonology Scientific Research Institute under Federal Medical and Biological Agency of Russian Federation, Moscow, Russia

2 Division of Fundamental Pulmonology of Federal State Budgetary Institution, Pulmonology Scientific Research Institute under Federal Medical and Biological Agency of Russian Federation, Moscow, Russia

\*Address all correspondence to: samary@mail.ru

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
