[Renal extramedullary hematopoiesis. Case report]

Extramedullary hematopoiesis (EMH) is defined as the formation and development of erythrocytic, granulocytic and megakaryocytic cell lines outside the bone marrow; it is a rare occurrence, which is limited to case reports.

To describe a case of renal EMH secondary to chronic hypoxia.

The patient is a 16 year old teenager who developed chronic hypoxia, central cyanosis, clubbing and lives more than 2,500 m above sea level. Chronic hypoxia is probably secondary to pulmonary hypertension, neither detected nor previously treated. The Consultation was due to a mass in the left upper quadrant for the last three months. An Echocardiogram showed pulmonary hypertension that could not be assessed by hemodynamic parameters. A computed tomography showed bilateral left renal pelvic masses. The hemogram showed polycythemia, so bone marrow aspiration was performed, which rule out malignant pathology. A biopsy of the renal mass reported EMH with three hematopoietic cell lines.

This EMH case is a response to chronic hypoxia rather than to a bone marrow lesion as it has usually been described.