Transmission electron microscopy of the preclinical phase of experimental phytophotodermatitis.

OBJECTIVE: To examine the epidermis in induced phytophotodermatitis using transmission electron microscopy in order to detect histologic changes even before lesions are visible by light microscopy. INTRODUCTION: In the first six hours after the experimental induction of phytophotodermatitis, no changes are detectable by light microscopy. Only after 24 hours can keratinocyte necrosis and epidermal vacuolization be detected histologically, and blisters form by 48 hours. METHODS: The dorsum of four adult rats (Rattus norvegicus) was manually epilated. After painting the right half of the rat with the peel juice of Tahiti lemon, they were exposed to sunlight for eight minutes under general anesthesia. The left side was used as the control and exposed to sunlight only. Biopsies were performed immediately after photoinduction and one and two hours later, and the tissue was analyzed by transmission electron microscopy. RESULTS: No histological changes were seen on the control side. Immediately after induction, vacuolization in keratinocytes was observed. After one hour, desmosomal changes were also observed in addition to vacuolization. Keratin filaments were not attached to the desmosomal plaque. Free desmosomes and membrane ruptures were also seen. At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed. DISCUSSION: The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation. CONCLUSIONS: Transmission electron microscopy can detect vacuolization, lesions of the membrane, and desmosomes in the first two hours after experimental induction of phytophotodermatitis.

Transmission electron microscopy of the preclinical phase of experimental phytophotodermatitis

OBJECTIVE: To examine the epidermis in induced phytophotodermatitis using transmission electron microscopy in order to detect histologic changes even before lesions are visible by light microscopy. INTRODUCTION: In the first six hours after the experimental induction of phytophotodermatitis, no changes are detectable by light microscopy. Only after 24 hours can keratinocyte necrosis and epidermal vacuolization be detected histologically, and blisters form by 48 hours. METHODS: The dorsum of four adult rats (Rattus norvegicus) was manually epilated. After painting the right half of the rat with the peel juice of Tahiti lemon, they were exposed to sunlight for eight minutes under general anesthesia. The left side was used as the control and exposed to sunlight only. Biopsies were performed immediately after photoinduction and one and two hours later, and the tissue was analyzed by transmission electron microscopy. RESULTS: No histological changes were seen on the control side. Immediately after induction, vacuolization in keratinocytes was observed. After one hour, desmosomal changes were also observed in addition to vacuolization. Keratin filaments were not attached to the desmosomal plaque. Free desmosomes and membrane ruptures were also seen. At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed. DISCUSSION: The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation. CONCLUSIONS: Transmission electron microscopy can detect vacuolization, lesions of the membrane, and desmosomes in the first two hours after experimental induction of phytophotodermatitis.

Mucocutaneous Leishmaniasis: a study of oral lesions by peroxidase-antiperoxidase technique / Leishmaniose muco-cutânea: estudo de lesões de boca pela técnica da peroxidase-antiperoxidase

A Leishmania Braziliensis, o agente etiológico da leishmaniose muco-cutânea, é um parasita de difícil visualização em cortes histológicos de rotina. Foram estudados oito casos de mucosa bucal pelo H.E. e técnica imuno-histoquímica. Observamos positividade de 5 dos 8 casos, para o anticorpo utilizado

Fatores prognósticos em carcinoma espinocelular de lábio inferior: estudo retrospectivo / Prognostic factors in squamous cell carcinoma of the lower lip: retrospective study

Análise retrospectiva de 58 prontuários de portadores de carcinoma espinocelular do lábio inferior, atendidos no período de janeiro de 1980 a dezembro de 1989, no Hospital das Clínicas da Faculdade de Medicina da Universidade de Säo Paulo. Além dos dados demográficos, foram considerados o uso de álcool, fumo e a exposiçäo solar, assim como o estado clínico na época da cirurgia, as características macroscópicas dos tumores, o tipo de tratamento instituído e as observaçöes do seguimento pós-operatório. Os espécimens cirúrgicos foram submetidos a minuciosa revisäo anátomo-patológica com análise do grau de diferenciaçäo histológica, espessura máxima tumoral, elastose solar, invasöes perineural, vascular e muscular, margens cirúrgicas, infiltrado inflamatório peritumoral e acometimento glanglionar, com ou sem rotura capsular. A análise da sobrevida global em 5 anos demonstrou valor prognóstico significativo para as seguintes variáveis: espessura tumoral, tamanho da neoplasia (T) e acometimento ganglionar

Salivary duct carcinoma: ultrastructural and histogenetic considerations / Carcinoma ductal de glândula salivar: considerações ultraestruturais e histogenéticas

Two cases of salivary duct carcinoma were examined by light and electron microscopy. Histologically, the tumor presented cribriform and papillary patterns together with comedonecrosis. Electron microscopy revealed duct cells with microvilli, interdigitations, and apical vesicles. No myoepithelial cells were observed. These findings suggest a ductal origin other than from the intercalated duct or its precursor element. The importance of separating the salivary gland adenocarcinomas is discussed