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Homme de 18 ans,présentant des lésions papuleuses millimétriques généralisées. |
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18 yo man, with a generalised small papular skin lesions. |
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- Forme rare d'éruption lichenoide
- se distingue du lichen plan par l'aspect clinique, l'histologie:
- papule de 1 à 2 mm de diamètre, plate ou légèrement bombée ou acuminée, blanche, brillante, ou parfois de la couleur de la peau normale, peu ou pas prurigineuse.
- groupements d'une dizaine de papules qui siègent au fourreau de la verge, aux poignets, au dos des mains, mais peuvent se généraliser.
- un infiltrat dense, bien limité, micronodulaire, sous l'épiderme atrophique, comportant des lymphocytes, parfois des plasmocytes, des histiocytes et des cellules géantes
- cette image pseudotuberculoïde qui caractérise le lichen nitidus.
- L'immunofluorescence directe est négative.
- asymptomatique, ne nécessite aucun traitement mais peut répondre aux corticoïdes topiques et aux antihistaminiques, voire à la PUVA.
in Dermatologie, H Saurat et al, 3ème Ed. Masson |
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- Small, glistening, flesh-colored to pink or reddish-brown papules may be limited to the penis, genitalia, abdomen, and extremities or less frequently may occur as a generalized condition
- the discrete, tiny papules of lichen planus are indistinguishable from those of lichen nitidus
- etiologic theory of lichen nitidus proposes that an allergen may cause epidermal and dermal antigen-presenting cells (e.g., Langerhans cells) to activate a cell-mediated response, initiate lymphocyte accumulation, and form discrete inflammatory papules. The presence of large numbers of Langerhans cells in the infiltrate supports this theory
- Occasionally, the papules are grouped and the isomorphic or Koebner's phenomenon is observed
- usually asymptomatic; however, pruritus is occasionally present and sometimes intense
- dense mass of infiltrating lymphohistiocytic cells is situated immediately below the epidermis and results in widening of the papillary dermis
- central parakeratosis without hypergranulosis.
- Colloid bodies are rarely seen in lichen nitidus
- dermal infiltrate is well circumscribed and composed of closely associated histiocytes, lymphocytes, and occasional foreign body or Touton-type giant cells
- some cases, the majority of the cells in the infiltrate are histiocytic
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