INTRODUCTION: The differential diagnosis of B-cell lymphoproliferative processes remains a challenge for pathologists, dermatologists and oncologists, despite advances in histology, immunohistochemistry and molecular biology. OBJECTIVE: Evaluate aid and limitations of clonality analysis in the diagnosis of primary cutaneous B-cell lymphomas and B-cell pseudolymphomas. METHODS: This study included 29 cases of B-cell lymphoproliferative processes classified as primary cutaneous B-cell lymphomas (13), B-cell pseudolymphomas (6) and inconclusive cases (10) using histology and immunohistochemistry. The clonality analysis was performed by polymerase chain reaction analysis of immunoglobulin light chain and heavy chain rearrangements. RESULTS: DNA quality was shown to be generally poor; eight samples were inadequate for polymerase chain reaction analysis. The results showed monoclonality in eight of the primary cutaneous B-cell lymphomas and polyclonality in four of the B-cell pseudolymphomas. In addition, monoclonality was shown in two of the inconclusive cases by histology and immunohistochemistry, demonstrating the utility of polymerase chain reaction as an ancillary diagnostic tool for primary cutaneous B-cell lymphomas. DISCUSSION: The low quality DNA extracted from these cases demanded the use of an IgH protocol that yielded small fragments and IgK. Both methods used together improved detection. CONCLUSION: Use of the two protocols, immunoglobulin heavy chain FR3-trad and immunoglobulin light chain-Kappa Biomed protocols for clonality analysis improved diagnostic accuracy.

O mecanismo de interação entre o Mycobacterium leprae e as células neurais não está esclarecido até o momento. Não há interpretação satisfatória do tropismo da bactéria ao sistema nervoso periférico, em particular. O presente estudo é uma revisão da microfisiologia da estrutura do aparelho extracelular, ligado às células de Schwann, assim como a descrição das unidades morfológicas, provavelmente envolvidas no processo de ligação à parede celular da bactéria.

The mechanism of interaction between Mycobacterium leprae and neural cells has not been elucidated so far. No satisfactory interpretation exists as to the bacterium tropism to the peripheral nervous system in particular. The present study is a review of the micro-physiology of the extracellular apparatus attached to Schwann cells, as well as on the description of morphological units probably involved in the process of the binding to the bacterial wall.

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.

São registrados três casos de feo-hifornicose subcutânea em transplantados renais provocados pela Exophiala jeanselmei (Langeron) McGinnis et Padhye 1977, fungo demácio capaz, também, de produzir raramente eumicetoma de grãos pretos. Este fungo, segundo KWON-CHUNG & BENNETT, 1992(27) é antigenicamente muito heterogêneo, sendo identificados até o presente momento três sorotipos com subgrupos dentro de cada um deles. A feo-hifomicose subcutânea vem se tornando cada vez mais freqüente em transplantados renais, submetidos a terapêutica imunodepressora. Como a Exophiala jeanselmei já foi isolada do meio ambiente, torna-se dificil explicar a patogenia desses casos por um despertar ou reativação de processos quiescentes. Os Autores fizeram ampla revisão da literatura, registrando principalmente os casos de feo-hifomicose publicados no Brasil. Sugerem também, eventual ação fungistática da ciclosporina A sobre a Exophiala jeanselmei.

We report three cases of subcutaneous phaeohy-phomycosis due to Exophiala jeanselmei (Langeron) McGinnis et Padhye 1977, in kidney transplant patients. Exophiala jeanselmei is a dematious fungus having also ability to rarely procedure eumycetoma (black grains). According to KWON-CHUNG & BENNETT (1992)27 such fungus is antigenically very heterogeneous, since so far three serotypes have been identified; each serotype including subgroups. Subcutaneous phaeohyphomycosis is becoming more and more frequent in kidney transplant patients submitted to an immunosupressive treatment. As Exophiala jeanselmei has already been isolated from the environment it becomes difficult to explain the pathogenicity of these cases by a reactivation of quiescent processes. The authors suggest an occasional fungistatic action of cyclosporine A upon Exophiala jeanselmei. A review of the literature was carried out with the report mainly of cases published in Brazil.