[Acquired regressive cutaneous non-Langerhans-cell histiocytosis in an infant].

Introduction: Cutaneous histiocytosis of childhood often regresses spontaneously without treatment. In some cases however, it is difficult to differentiate aggressive forms and electron microscopy and immunohistochemistry can be a valuable help. We report a case of cutaneous histiocytosis in a child which illustrates the difficulties encountered in the classification of histiocytosis.

[Waldenstrom's macroglobulinemia with antibasement membrane activity of monoclonal immunoglobulin].

Introduction: Waldenström macroglobulinemia is a rare hematologic disorder with characteristic malignant plasma cell proliferation associated with the secretion of a IgM monoclonal immunoglobulin which is the cause of most of the clinical manifestations. Skin involvement is exceptional. We report a new case of Waldenström macroglobulinemia discovered in a patient who developed specific skin lesions with monoclonal immunoglobulin deposits.

[Cutaneous hypersensitivity at the site of injection of vitamin K1].

Introduction: Skin reactions after vitamin K injections are uncommon and only seen with vitamin K1 (phytomenadione). Possible association with liver disease is debated. The pathophysiological mechanism would be related to hypersensitivity to phytomenadione.