Kohli, A.

Abstract Introduction Extramedullary hematopoiesis (EMH) is the production of blood cells outside of bone marrow. It is associated with myeloproliferative neoplasms such as myelofibrosis and chronic myeloid leukemia. Most common sites for EMH are liver and spleen, but other sites may be involved. Pulmonary EMH is extremely rare. It is associated with symptoms of dyspnea, cough or chest pain. Chest imaging may demonstrate pulmonary nodules or masses, alveolar septal thickening, ground glass opacities, and/or patchy consolidations. We present a case of a woman with primary myelofibrosis who developed pulmonary hypertension (PH) in the setting of pulmonary EMH. Case description 73-year-old woman with history of primary myelofibrosis (diagnosed via bone marrow biopsy, grade 3 fibrosis, being treated with hydroxyurea) presented with progressive exertional dyspnea for 1.5 years. Exam was notable for elevated jugular venous pressure and mild peripheral edema. Labs revealed anemia with hemoglobin 8.2 g/dL, thrombocytosis with platelets 549K/dL and no leukocytosis. Brain natriuretic peptide was elevated at 1361 ng/L. Chest CT demonstrated few peripheral wedge-shaped opacities in the bilateral lower lobes were noted. Pulmonary function tests revealed normal spirometry and lung volumes but moderately reduced diffusion capacity. Echocardiogram showed normal left ventricular (LV) size and function with ejection fraction 60%, moderately enlarged right ventricle (RV) and RV systolic pressure 63 mmHg. Right heart catheterization showed RA pressure:14 mmHg, PA: 49/26/36 mmHg, PCWP 15mmHg, thermodilution CO 5.5 L/min, CI 3.1L/min/m2, Fick CO 4.6 L/min, CI 2.6 L/min/m2, pulmonary vascular resistance 3.8-4.6 Woods Units. Given her history of myelofibrosis, Tc-99m bone marrow scan was performed which showed diffuse radiotracer uptake in both lungs suggestive of pulmonary EMH. She subsequently underwent radiation therapy with 100cGy to bilateral lungs. On a follow-up visit two months later, she reported symptomatic improvement. Repeat NM bone scan showed decreased tracer uptake in the lungs. Discussion PH associated with myeloproliferative neoplasia is classified as group 5 in the latest clinical classification. It can be due to thrombocytosis, hypercoagulability, left ventricular failure, portal hypertension and/or hematopoietic infiltration of the pulmonary parenchyma. Tc-99m sulfur colloid scanning can be used to detect hematopoietic tissue in the lung. Treatment is usually radiation-therapy to the lungs to control the hematopoiesis. In patients with myeloproliferative neoplasms presenting with dyspnea, consider screening for PH with echocardiogram.