[IgD myeloma with skin tumor].

A 66-year-old man was treated for IgD (lambda) multiple myeloma with 2mg/day melphalan and 20mg/day prednisolone. Subsequently, he developed pneumonia for which he received antibiotics, an antifungal agent and granulocyte colony-stimulating factor (G-CSF) twice. Myeloma cells appeared in the peripheral blood 10 days after the second G-CSF course. In addition, skin tumors developed on his extremities and chest 14 days after the second use of G-CSF. The skin tumors consisted of immunohistochemically IgD (lambda)-positive myeloma cells. The skin tumors may have been formed from the bone marrow by metastasis, a very rare occurrence in multiple myeloma. Before the development of the tumors we administered G-CSF, which may also have been related to the formation of the skin tumors.