Chozaburo Okuda

Disseminated cutaneous Fusarium infection with vascular invasion in a leukemic patient

A 61-year-old male with leukemia manifested multiple cutaneous nodules on his whole body surface, subcutaneous nodules on his arms and a tongue tumor. Septate hyphae were observed microscopically in scrapings from the surfaces of the cutaneous lesions. Fusarium solani and F. anthophilum were isolated from scrapings from the several skin lesions. Histological examination revealed the presence of numerous septate hyphae in the lumina of vessels in the dermis. The fungal elements in the cutaneous tissues were suggested to be Fusarium by an immunoperoxidase method using a genus-specific anti-Fusarium antibody. Although no evidence of fungal infection was found in other organs by clinical examinations, F. solani and/or F. anthophilum were considered to have undergone hematogenous dissemination, because of the presence of thrombi containing abundant fungal elements in the skin lesion. The present case is a case of disseminated cutaneous Fusarium infection, in which fungal elements in skin tissue sections were immunohistochemically regarded as Fusarium, though fungus cultures from biopsied specimens were negative.

Fungus invasion of human hair tissue in tinea capitis caused by Microsporum canis: light and electron microscopic study

SummaryPreviously, we reported a morphological change of Trichophyton violaceum in hair tissue in black dot ringworm. To investigate the morphology of Microsporum canis in human hair tissue, three cases of tinea capitis by M. canis were examined by both light and electron microscopy. The fungal elements, which were located deeply in the keratogenous zone, showed nonseptate hyphae in the outer part of the hair cortex. With the upward development of hair tissues, some hyphae invaded the keratinized inner root sheath and were there transformed into arthrospores, which then occupied the large volume of the inner root sheath; each spore was surrounded by an electron-lucent halo. In some affected hair follicles, at the follicular isthmus level, a microabscess composed of polymorphonuclear leukocytes was often formed in the outer root sheath adjacent to the arthrospores in the keratinized inner root sheath. On the other hand, the remaining hyphae in the cortex became degenerated. Fungi did not invade the hair-germinative cells. There is a distinct relationship between the morphological change of fungi and the differentiation of hair cells in tinea capitis by M. canis as well as in that by T. violaceum, although the direction of invasion and pathological roles of fungal elements within hair tissue are significantly different between the two species of fungi.

Trichophyton rubrum invasion of human hair apparatus in tinea capitis and tinea barbae : light- and electron microscopic study

SummaryWe have previously reported morphological changes ofTrichophyton violaceum andMicrosporum canis in hair apparatuses in tinea capitis. To investigate the morphology ofTrichophyton rubrum in the human hair apparatus, two cases of tinea capitis and one case of tinea barbae were examined by light- and electron microscopy. The fungal elements, which were located in the lower keratogenous zone, showed non-septate hyphae in the outer part of the hair cortex. With the upward development of the hair layers, some hyphae invaded the keratinized hair cuticle and keratinized inner root sheath and were transformed into arthrospores. Some hyphae remaining in the hair cortex were also transformed into arthrospores, while other hyphae in the hair cortex did not survive, but degenerated. InT. rubrum hair infection, there is a distinct relationship between the morphological changes of the fungi and the hair cell differentiation as seen inT. violaceum andM. canis infections. However,T. rubrum displays unique morphological changes, which are different from those ofT. violaceum andM. canis, in hair apparatuses.

Relationship between tissue reactions and morphological changes of the fungi in chromoblastomycosis : morphometry and electron microscopy

SummaryTo investigate the histological distribution and the morphology of the fungi and the tissue reactions in chromoblastomycosis, especially in the process of trans-epidermal elimination, cutaneous lesions of two patients with this disease were studied morphometrically and ultrastructurally. In the dermis, most of the fungal elements appeared as sclerotic cells and their cell wall showed an irregular, worm-eaten leaf-like appearance; they seemed to be continuously attacked by polymorphonuclear neutrophils. The epidermis eliminated 10–20% of all the organisms in the skin lesions, and the hypha-forming activity tended to be higher in the epidermis than in the dermis. Ultrastructurally, basal keratinocytes facing the dermal abscess containing fungal elements frequently appeared as dark cells, suggesting an increased proliferation activity. Spinous keratinocytes facing intraepidermal microabscesses containing fungal elements showed an abnormal accumulation of tonofilaments and further early keratinization in the spinous cell layer. All of the morphological changes of the dermis and epidermis are regarded as defence reactions against the fungi existing in the skin lesions. There is a close relationship between tissue reactions and morphological changes of fungi in chromoblastomycosis.