Pathology of Phycomycosis

Abstract

Phycomycosis is an acute and fluminant fungous infection in debilitated patients, but generally the diagnosis of the disease has been made histopathologically in autopsy cases. In Japan, it may be restricted to mucormycosis caused by several species of the genera Rhizopus, Mucor and Absidia. Therefore, the following descriptions refer to the mucormycosis.
In histopathology, mucormycosis is characterized by direct invasion of fungi to the walls of arteries and thrombosis, which cause infarction and hemorrhagic necrosis of adjacent tissue. The hyphae in tissue are greatly broad (5 to 50μ), sparsely septate, and haphazardly branched. Furthermore, in contrast to most fungi, the hyphae are fairly well stained with hematoxylin, but not constantly. The Gomori methenamine silver stain is more preferable than the other staining methods for fungi.
Mucormycosis is usually a secondary infection. Baker emphasized diabetes and blood diseases as the most frequently antecedent conditions in 1957. In our statistical survery of deep-seated mycoses using the Annual of the Pathological Autopsy Cases in Japan during the ten year period from 1966 to 1975, 154 cases of mucormycosis were reported, which were 0.068% of 224, 436 all autopsy cases and 3.45% of the total of 4, 464 autopsy cases of mycoses. In this series, leukemias were present in 61% of the cases of mucormycosis, although diabetes was in 1% of them. In addition, anticancer and corticosteroid therapies for blood diseases and malignant neoplasms were emphasized as predisposing factors in the experimental studies in the rabbits pretreated with cyclophosphamide, mitomycin C and predonine.