Table 1.

Anatomopathological grading of avian aspergillosis

Grade	Gross lesions	Microscopic lesions
Grade 0	No obvious pathological changes were observed in the trachea, bronchi, lungs, and air sacs.	Normal histoarchitecture was maintained in the trachea, bronchi, lungs, and air sacs. No fungal elements in routine histopathology or special staining
Grade 1	Focal miliary plaques or amorphous necrotic lesions involving <10% of lung portion in one or both lung lobes, Airsacs appeared normal.	Focal areas of caseous necrosis with or without intralesional fungal elements, surrounded by marked congestion of air capillaries and parabronchial vessels. Fungal elements may not be detectable by routine histopathology; however, the conidial wall can be demonstrated by special staining for melanin.
Grade 2	Multifocal raised soft to firm nodular lesions involving up to 30% of the lung parenchyma, while other portions of the lung exhibited only congestion. The clavicular, thoracic, or abdominal air sacs may become cloudy and show plaque-like lesions.	Multifocal areas of extensive tissue necrosis with intralesional colonies of fungal elements were predominantly surrounded by heterophils and fewer lymphocytes with restricted tissue invasion; nonetheless, no granulomatous reaction was usually observed. Fungal hyphae or conidiophores may be found in aerated air sacs.
Grade 3	Multifocal to coalescing pleomorphic firm to hard nodules in lungs involved up to 30%-60% of parenchyma. Plaques and firm greyish to yellowish nodules in air sacs	Multiple foci of caseation necrosis were surrounded by typical granulomatous reaction characterized by a large number of macrophages, multinucleated giant cells, and lymphocytes in lungs, air sacs, and other communicating organs or multiple areas of pyogranulomatous reaction with fungal hyphae and conidia. Tissue destruction and fungal invasion were widespread.
Grade 4	Random or diffuse pleomorphic mixed type (soft/firm/hard) of granulomatous or pyogranulomatous nodules in lungs involving up to 60%-80% of parenchyma, observed on air sacs, peritoneum, and serous membrane of other visceral organs, including blood vessels wall.	Typical mycotic granulomas with or without fibro-vascular reaction in the respiratory system, as well as other organs. The fungal hyphae may be found invading the blood vessels wall and into the lumen (angioinvasive). There may be infection and inflammation on distant non-communicating organs.
Grade X	Peracute form: severely congested and edematous lungs, No distinct nodules	Lung parenchyma revealed diffuse congestion of blood vessels, leaky or collapsed air capillaries, and exuberant invasion by fungal hyphae and conidia. No granulomatous lesions were detected in the lungs.