Adiaspiromycosis in a wild European rabbit, and a review of the literature - PubMed (original) (raw)

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Adiaspiromycosis in a wild European rabbit, and a review of the literature

Katherine Hughes et al. J Vet Diagn Invest. 2018 Jul.

Abstract

Adiaspiromycosis is a mycotic infection caused by thermally dimorphic fungi classified as Emmonsia parva and E. crescens (formerly Chrysosporium spp.) until recently, when new classifications were proposed. We document the pathologic findings in a severe case of adiaspiromycosis, with lymph node involvement, in a wild European rabbit ( Oryctolagus cuniculus). The rabbit exhibited granulomatous pneumonia with tracheobronchial lymph node enlargement. Histopathologically, the lung was expanded by myriad, densely cellular, heterophilic and granulomatous foci, surrounding bi- to trilaminar adiaspores. Adiaspore density was considered to be similar in all lung lobes. In the left caudal lung lobe, 80 adiaspores were counted in a 50-mm2 area using digital image analysis. The mean and median adiaspore diameters were 240 ± 52 μm and 255 μm, respectively. Tracheobronchial lymph nodes exhibited moderate numbers of similar adiaspores. PCR amplification of DNA extracted from microdissected adiaspores failed to identify Emmonsia spp.-specific DNA. These data suggest that adiaspiromycosis may result in severe granulomatous pneumonia in wild European rabbits. Although confirmation of the etiologic agent by PCR using DNA extracted from formalin-fixed tissue is not always successful, digital image analysis can be used to aid accurate assessment of adiaspore density and morphology.

Keywords: Adiaspiromycosis; Emmonsia; Oryctolagus cuniculus; digital pathology; lung; lymph node; rabbits.

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Conflict of interest statement

Declaration of conflicting interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figures 1–7.

Figures 1–7.

Pulmonary adiaspiromycosis in a wild European rabbit (Oryctolagus cuniculus). Figure 1. The lungs were firm and expanded by myriad granulomas. Figure 2. The cut surface of the left caudal lung lobe was expanded by variably sized, coalescent, granulomas (arrows). Formalin-fixed tissue. Figure 3. Numerous densely cellular foci surrounding spore-like adiaspores are present throughout the lung. H&E. Figure 4. Adiaspores exhibit a bi- to trilaminar wall (arrow) comprising a thin, brightly eosinophilic outer layer, and a thick, pale eosinophilic inner layer surrounding a core of basophilic granular-to-foamy material (asterisk). Adiaspores are surrounded by heterophils, macrophages, multinucleate giant cells (arrowhead), lymphocytes, and plasma cells, in variable proportions, with interspersed fibroblasts. H&E. Figure 5. The adiaspore wall is stained intensely positive with periodic acid–Schiff stain. Multifocally, adiaspores are surrounded by multinucleate giant cells with >40 nuclei (arrowhead). Figure 6. The adiaspore wall exhibits intense staining with Grocott methenamine silver stain (arrow). Figure 7. Similar adiaspores (arrow) are present within the tracheobronchial lymph node. Large multinucleate giant cells are also evident multifocally in this case within the subcapsular sinus (arrowheads).

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