1. Scheme indicating comparison in hyphal distribution
in the lesion IPA between DN and BR.Kazutoshi SHIBUYA MD, Department
of Pathology, Toho University Ohashi Hospital, 2-17-6 Ohashi Meguro-ku, Tokyo153-8515,
JAPAN
Phone: 81-3-3468-1251,
Fax: 81-3-3468-1283, E-mail:
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This article is a summary of histopathological study on more than fifty autopsies of invasive pulmonary aspergillosis.
A large body of Aspergillus lesions was classified into two identical histopathological patterns; Discrete nodule (DN) [Nodule of coagulation necrosis with peripheral hemorrhage], and Aspergillus bronchopneumonia (BR) [Fused lobular consolidation with liquefaction necrosis]
Discrete nodules are characterized by a scattering of defined nodules of up to 30 mm diameter, which are composed of coagulation necrosis and numerous hyphae aligned themselves in a radial pattern. None have visible neutrophils and other inflammatory cells in the lesion. This pattern is usually demonstrated in a patient with severe bone barrow suppression. Thus, the patient showed aggressive and fluminant clinical course.
Aspergillus bronchopneumonia, is characterized by acute inflammatory exudation consisting of neutrophils, fibrin and a little necrosis in alveoli with focal proliferation of fungi. Gross appearance of the lesion is composed of fusion of lobular consolidation. Cavity formation is occasionally included in this pattern, which is mostly produced by an exclusion of lung tissue with liquefaction necrosis, and by the draining effect of bronchus involved by the lesion. This pattern is particularly observed in a patient with rather mildly suppressed bone marrow or some types of immunodeficiency, e.g., patient with diabetes, steroid administration, and so on.
Accordingly, most of the cavities demonstrated in this disease may be the result of liquefaction necrosis due to tissue toxicity of infiltrating neutrophils.
Figure legends
1. Scheme indicating comparison in hyphal distribution
in the lesion IPA between DN and BR.
2. Section of the lung showing BR pattern. The lesion
is composed of creamy yellowish fused lobular consolidation containing necrotic
cavity in the center.
3. Microphotograph of BR, showing dense neutrophiilic
infiltrate with disappearance of septa (HE stain, x200).
4. Microphotograph of BR, showing palisading arrangement
of hyphae at periphery of the lesion (Grocott's stain, x200).
5. Scheme explaining architecture of BR pattern.
6. Section of the lung showing DN pattern. The photograph
shows three uniform defined nodules on the section with an association of surrounding
hemorrhage. No cavities are found. The feature is essentially mimicking that
of metastatic carcinoma in lung.
7. Microphotograph of DN. The nodule is composed
of coagulation necrosis of the lung tissue without any types of inflammatory
infiltrates. Blood vessels involved by the lesion are occluded, and the nodule
is encompassed with fresh hemorrhage (HE stain, x2).
8. Microphotograph of DN. Numerous hyphae align
themselves in a radial pattern in the lesion (Grocott's stain, x200).