Myelophthisis

Myelophthisis, also known as myelophthisic anemia, is a form of bone marrow failure characterized by the displacement of normal hematopoietic tissue by abnormal tissue, such as tumor cells, granulomas, or fibrosis. This infiltration impairs the bone marrow's ability to produce adequate numbers of blood cells, leading to pancytopenia, leukoerythroblastosis, and often extramedullary hematopoiesis.

This code is used when documentation clearly indicates the presence of myelophthisis as the underlying cause of bone marrow dysfunction. It is typically supported by bone marrow biopsy findings demonstrating infiltration by malignant cells (e.g., metastatic carcinoma, leukemia, lymphoma), granulomatous disease, or severe fibrosis. This diagnosis explains the resulting cytopenias.

• Always code the underlying cause of the myelophthisis (e.g., malignancy, granulomatous disease) first, as this code represents a manifestation.
• Distinguish from aplastic anemia (284.8) where bone marrow failure is due to hypoplasia or aplasia without significant infiltration.
• Ensure documentation specifies "myelophthisis" or describes bone marrow replacement by abnormal tissue leading to hematopoietic failure.