Deep fungal disease Parasitosis and Deep fungal disease Tian Dong Ping 田东萍 Dept. of Pathology Shantou University Medical College

Amoebic dysentery

Ⅰ. Etiology: Amaebiasis is also an infectious disease of digestive tract——caused by entamoeba histolytica. Two forms- trophozoites and cysts: cysts are ingested- enter the lower part of ileum and upper part of the colon- transform to trophozoites

Ⅱ. Pathogenesis: The trophozoites penetrate the mucosa and release membrane- bound cytolytic ezymes – damage of mucosa (liquefactive necrosis), cytotoxin- enterotoxin- caused diarrhea and mucosa damage

Ⅲ. Pathological changes: Location- cecum, ascending colon, sigmoid and rectum There are stages

Grossly: Solitary or multiple, 80% right lobe, 10% left lobe, 10% both The abscess contains a brown-pasty material (liquefactive necrosis and old blood) it appears ragged due to incompletely liquefied necrosis

1. Acute lesion The initial lesion is located in the surface of intes-tinal mucosa- crypts of colonic glands Multiple elevated lesion with grayish- yellow color can be seen- necrotic- superficial ulceration. The trophozoites penetrate the muscularis mucosa into the submucosa- large undermined flask- shaped ulceration can be seen The trophozoites found between viable tissue and necrotic tissoe.

Amebiasis of the colon with a portion of three Entamoeba histolytica trophozoites

Clinically: Abdominal pain diarrhea Stools contain mucus blood and necrotic tissue

2. Chronic stage: The pathological changes are very complicated – necrosis, ulceration, granulation tissue and scar formation may alternate polyp formation fibrosis Amoebic liver abscess The parasite reach the liver through the portal vein.

Clinically Fever, abdominal pain at right upper part of the abdomen The liver is enlarged and tender.

Deep fungal disease

Disease caused by fungi are called mycosis two groups: 1. The superficial mycosis—dermatophytosis 2. The deep or systemic mycosis- candiasis, aspergillosis, cryptococcosis, mucormycosis. Pathogenesis of fungi may be related to the mechanical injury caused by proliferative the fungus or to the metabolic products or enzymes.

Factors which can reduce host resistance and induce mycosis are as follows: 1.chronic debilitating disease 2.The growing use of wide spectrum antibi-otics, radiation, immunosuppressive drugs. 3. Treatment with steroid drugs 4. Iatrogenic factors

Basic pathological change of deep fungal diseases are as follows: 1. Suppurative inflammation-acute suppurative inflammation, chronic suppurative inflammation, or microabscess— mucormycosis, Aspergillosis, Actinomycosis 2. Granulomatous lesion- candidiasis

3. Fungi invade vessels leading to hematogenous spread and thrombosis. Infarction-mucomycosis, aspergillosis 4. Some form pseudomembrane- thrush. Some form vegetation lesion on the heart valves. Candidiasis

candidiasis candidiasis is one of the most common causes of human fungal disease. Pathological changes: 1. There are three types basic lesions. (1) moncytes lymphocytes and neutrophilic infiltration. (2) Disuse necrosis Granulomatous reaction (uncommon)

2.Lesion of skin and mucosa: pseudomembrane. Candidiasis of the mucous membrane of the mouth is known as thrush. 3. systemic candidiasis

A.Severe candidiasis of the distal esophagus. B silver stain of a section of the same lesion reveals the dense mat of Candida B A

cryptococcosis cryptococcosis is caused by cryptococous neoformans it usually infects the central nervous systems the lung, skin bone. Pathological change: 1. It causes chronic inflammation chronic granulomatous reaoction. 2. cryptococcoal meningitis: The meninges are thickened particularly at the base of the brain. The infection extends into the brain It produces small cysts filled with cryptocci granulomatous lesion.

cryptococcosis Fungi invade vessels leading to hematogenous spread and thrombosis. Infarction- mucomycosis,

Mucormmcosis Pathological change: 1. Acute suppurative inflammation. The nonseptate wide fungal hyphae with marked right angle branching are demonstrated in the necrotic tissue 2. The fungi invade vessel- Thrombosis- infarction. hemo to genous spread.

Aspergillosis Aspergillosis is caused by asperillus fumigates. Pathological change: 1.Basic change- suppurative inflammation, microabscess, chronic change is granulomatous lesion 2. Aspergillus tends to invade vessels: (1) Thrombosis infarction. (2) Hemotogenous spread. 3. Aspergillosis of heart valve- vegetation

Aspergillosis Some form pseudomembrane- thrush. Some form vegetation lesion on the heart valves.

Aspergillus colony showing fruiting body and septate hyphae in the nasal septum (silver stain)_

Actinomycosis Actinomycosis chiefly occur in the cervico- cacial region about 50%. Pathological change: (1) chronic suppurative inflammation. The old lesion with fibrosis and the new lesions with abscess formation can be seen at the same time. (2). Abscess- sinus fistula (3) actinomycosis often contain other mixed bacterial infection.

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