title: Case of polycythemia vera with unusual organizing pneumonia mimicking the clinical features of military tuberculosis and possibly caused by the involvement of neoplastic megakaryocytes.
abstract: Polycythemia vera (PV) is a clonal myeloproliferative neoplasm (MPN) of hematopoietic stem cells. Although the management of MPN patients generally focuses on the prevention of thromboembolic events caused by hypercoagulability, it is true that the patients with hematological malignancy often suffer from pulmonary diseases with atypical radiological patterns. We present here a 56-year-old woman with PV harboring a JAK2(V617F) mutation that had a diffuse reticulonodular pattern on chest radiography and was initially suspected of having military tuberculosis. Pathological assessment of a video-assisted thoracoscopic surgery lung biopsy revealed that the lesions were in fact organizing pneumonia (OP). Interestingly, pulmonary extramedullary hematopoiesis with a diffuse plugging of the alveolar blood capillaries by numerous atypical megakaryocytes was also observed around the granulation components. The histological findings of our case of unusual OP suggest that local activated neoplastic megakaryocytes and platelets played an important role in the development of spreading fibrotic lesions. JAK2 mutation or the preleukemic phase of MPN may accelerate the activation of megakaryocytes and result in the proliferative process of fibrosis.
authors.affiliation: Department of Pathology, School of Medicine, Kurume University, Kurume-city, Fukuoka, Japan. yoshizo830@yahoo.co.jp
authors.forename: Yoshizo
authors.initials: Y
authors.lastname: Kimura
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Imamura
authors.forename: Koichi
authors.initials: K
authors.lastname: Higaki
authors.forename: Yuju
authors.initials: Y
authors.lastname: Ohno
authors.forename: Namiko
authors.initials: N
authors.lastname: Hashiguchi
authors.forename: Rituko
authors.initials: R
authors.lastname: Seki
authors.forename: Takashi
authors.initials: T
authors.lastname: Okamura
authors.forename: Fumiko
authors.initials: F
authors.lastname: Arakawa
authors.forename: Junichi
authors.initials: J
authors.lastname: Kiyasu
authors.forename: Masanori
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Miyoshi
authors.forename: Maki
authors.initials: M
authors.lastname: Yoshida
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Daisuke
authors.initials: D
authors.lastname: Niino
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Sugita
authors.forename: Koichi
authors.initials: K
authors.lastname: Ohshima
mesh_terms: D003937:Diagnosis, Differential; D017809:Fatal Outcome; D005260:Female; D006411:Hematopoiesis, Extramedullary / Q000235:genetics; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics / Q000378:metabolism; D008533:Megakaryocytes / Q000473:pathology*; D008875:Middle Aged; D009154:Mutation; D011014:Pneumonia / Q000150:complications / Q000175:diagnosis*; D011087:Polycythemia Vera / Q000150:complications / Q000175:diagnosis* / Q000235:genetics; D013902:Radiography, Thoracic; D014391:Tuberculosis, Miliary / Q000175:diagnosis*
chemical_list: C507924:JAK2 protein, human; D053614:Janus Kinase 2