Extramedullary hematopoiesis may involve the lungs, resulting in a number of clinical and pathologic findings. The presence of hematopoietic cells in the lungs may be the first indication of myelofibrosis or other hematologic disorder.


Clinical findings:

(1) dyspnea

(2) orthopnea

(3) cough

(4) pleural effusion

(5) pleuritic chest pain

(6) hemoptysis


Imaging findings:

(1) pulmonary infiltrate


Laboratory findings:

(1) anemia and leukoerythroblastosis


Pathologic locations of hematopoietic cells:

(1) interstitial infiltrates

(2) within the alveolar airspace and/or alveolar wall

(3) within vascular lumina and/or vascular walls (especially subintimal) and/or perivascular infiltrates

(4) peribronchial infiltrates

(5) mass-like infiltrate

(6) pleura


The infiltrates of hematopoietic cells may consist of:

(1) megakaryocytes (CD61 positive)

(2) erythroid precursors (hemoglobin positive)

(3) myeloid precursors (myeloperoxidase positive)


Additional pathologic findings may include:

(1) interstitial fibrosis

(2) intra-alveolar hemorrhage


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