Extramedullary hematopoiesis in a bronchial carcinoid tumor. An unusual complication of agnogenic myeloid metaplasia.

A case of bronchial carcinoid tumor with foci of extramedullary hematopoiesis is presented. The patient had a 6-year history of agnogenic myeloid metaplasia and hepatosplenomegaly. All three hematopoietic cell lines were represented in different areas of the bronchial tumor. To our knowledge, this is the first case of extramedullary hematopoiesis described in a bronchial carcinoid and only the fourth report of hematopoietic cells in a neoplasm of otherwise unrelated origin. The pathogenesis of this uncommon finding is discussed and the literature is reviewed.