Skin manifestation of agnogenic myeloid metaplasia.

Agnogenic myeloid metaplasia (AMN) with myelofibrosis is a clonal malignancy of the hematopoietic stem cell. The disease is characterized by increased endothelial cell and fibroblast proliferation, resulting in increased deposition of fibronectin, laminin, and collagen in the bone marrow. In advanced disease, extramedullary hematopoiesis (EMH) is invariably seen in the spleen and liver. The lymph nodes are also frequent sites of EMH, but other organs, especially the kidneys, arenals, lungs, pleura, ovaries, gastrointestinal tract, and dura, may also be involved. Skin manifestations are rare. They may present in several ways: erythematous plaques, nodules, diffuse or papular erythema, ulcers, and bullae. Histopathology of these lesions reveals cells from one or more myeloid lineage in the dermis, erythroid, or megakaryocytic series alone or in combination. In rare cases, all three cell lines are demonstrated.