INTRODUCTION:The diagnosis and management of Interstitial Lung Disease can be challenging. We report a case of Interstitial Lung Disease due to an unusual cause.
CASE PRESENTATION:76 year old gentleman with past history of hypertension, DM and prostate cancer was diagnosed with myelofibrosis in November 2000 by bone marrow biopsy. He was subsequently treated with hydroxyurea in 2006 for thrombocytosis which was discontinued due to severe anemia. He was referred to pulmonary clinic in February 2007 for evaluation of progressively worsening shortness of breath for more than a month. He denied paroxysmal nocturnal dyspnea or orthopnea. He gave history of cough with whitish expectoration for last few months. Review of systems was otherwise unremarkable. He has a 25 packyear smoking history. No significant family, social and occupational history. He did not have any pets at home. Physical examination revealed end inspiratory rales in mid lung fields. Pulse oximetry was 90% on room air. Labs revealed hemoglobin: 9.5, WBC: 6.9, platelet: 720000, BNP: 34. His rheumatologic work-up including ANA, rheumatoid factor, C-ANCA, P-ANCA were negative. Hepatitis profile and HIV were also negative. Chest X-ray showed bilateral interstitial infiltrates. CT chest revealed diffuse ground glass opacity, interlobular septal thickening and mediastinal lymphadenopathy( Fig 1). Left ventricular ejection fraction was normal by echocardiogram. PFT showed evidence of mild restriction. Bronchoscopy with transbronchial lung biopsy was done from right upper and lower lobes and transbronchial needle aspiration (TBNA) of the subcarinal lymph nodes were performed. All the cultures from BAL were negative.Pathology from the transbronchial lung biopsy revealed benign lung parenchyma with interstitial fibrosis and interstitial inflammatory infiltrate and nucleated red blood cells, eosinophils, mononucleated cells and megakaryocytes suggestive of extramedullary hematopoiesis( Fig 2). TBNA was non-diagnostic. Patient underwent mediastinoscopy for lymph node biopsy, pathology of which was reported as presence of erythroid, myeloid precursors and magakaryocytes suggestive of extramedullary hemtopioesis (EMH).
DISCUSSIONS:EMH, which presents itself during the 6th or 7th decade of life, usually occurs in myelofibrosis and involves the reticuloendothelial system including the spleen, lymph nodes and liver. However, other uncommon sites of involvement include thorax, kidney, GI tract, breast, uterus, ovaries, choroid and meninges (1). EMH presenting as paraspinal masses have also been described. Thoracic involvement of EMH includes the pleura, lung parenchyma and mediastinal lymphnodes. While it is unclear how EMH develops in the lungs, Glew et al have proposed two possible ways: (i) in situ development of EMH in the lungs; (ii) embolisation of EMH from other organs (1). EMH in the lungs could manifest itself as a hemothorax from pleural involvement, chronic progressive disease with worsening dyspnea from interstitial involvement as seen in our case. EMH in the lung presenting as acute respiratory failure has also been reported. Interstitial involvement can also present as pulmonary fibrosis in the form of alveolar or septal fibrosis. Pulmonary hypertension also occurs secondary to EMH in the lung. Most cases of pulmonary EMH have antecedent hematological problems however de novo pulmonary involvement has also been reported. There are reports where Tc 99m Tin Colloid Scintigraphy could be useful in diagnosing pulmonary EMH. Various management strategies have been tried including steroid, hydroxyurea and low dose whole lung radiation (2). However, there is no clear consensus on management of pulmonary EMH.
CONCLUSION:Extramedullary hematopoeisis, though rare, should be entertained in the differential diagnosis of interstitial lung disease in patients with underlying hematologic disease as seen in our patient.
DISCLOSURE:Gnananandh Jayaraman, No Financial Disclosure Information; No Product/Research Disclosure Information