Extramedullary hematopoiesis mimicking metastatic lung carcinoma.

Extramedullary hematopoiesis is a rare condition defined as the appearance of hematopoietic elements outside of the bone marrow, which occurs primarily in patients with chronic myeloproliferative disorders or congenital hemolytic anemias. We report a patient who presented with a left lower lobe lung carcinoma and right paravertebral and left pleural masses, initially thought most consistent radiographically with inoperable metastatic disease, until biopsies of the paravertebral and pleural masses established the presence of extramedullary hematopoiesis. The left lower lobe neoplasm was subsequently resected uneventfully.