An 80-year-old man was diagnosed with PMF 3 years prior to hospital admission, as confirmed by bone marrow biopsy, expressing the JAK2 V617 F mutation but with no mutations in MPL exon 10 and CALR. His medical history included herpes zoster at 79 years of age, sick sinus syndrome controlled by a permanent pacemaker, and pulmonary tuberculosis, which was partially treated at 18 years of age because isoniazid and pyrazinamide was not approved in Japan at that time, and rifampin and ethambutol had not been discovered. He did not recently have contact with patients with tuberculosis or have family or friends with a tuberculosis history. He was treated with 20 mg ruxolitinib twice daily 10 months prior to admission. Ruxolitinib induced rapid symptom relief and therefore was reduced to 15 mg twice daily, and prednisolone at 20 mg daily was started 8 months prior to admission. As his general condition improved, the prednisolone dose was gradually reduced from 20 to 5 mg. Two weeks prior to admission, he had a fever, back pain, and multiple nodules in the left femur, inguinal node, and armpit. An unenhanced chest and spine computed tomography scan demonstrated the nodules, as well as bilateral miliary shadows, in the lungs (Fig. 1) and bone destruction in thoracic vertebrae 8/9 (Fig. 2). Laboratory findings on admission were as follows: white blood cell count, 6900/muL; C-reactive protein, 7.6 mg/dL; creatinine, 1.19 mg/dL; blood urea nitrogen, 22.6 mg/dL; aspartate aminotransferase, 52 U/L; alanine aminotransferase, 45 U/L; alkaline phosphatase, 318 U/L; gamma-glutamyl transpeptidase, 62 U/L; total bilirubin, 1.17 mg/dL; glucose, 138 mg/dL; HbA1c, 5.4 %. The interferon-gamma release assay (IGRA; Interferon-QuantiFERON-TB) test on admission was positive. He was hospitalized for suspected disseminated tuberculosis. Microbiological examination of his sputum showed positive acid-alcohol resistant bacilli, and polymerase chain reaction and culture were both positive for Mycobacterium tuberculosis, which was susceptible to all anti-tuberculosis drugs. We diagnosed disseminated tuberculosis, including tuberculous spondylitis, pulmonary tuberculosis, and skin tuberculosis. The standard tuberculosis treatment (300 mg isoniazid, 450 mg rifampin, and l500 mg ethambutol once daily) was started, and his general condition gradually improved. We did not administer pyrazinamide, because he was over 80 years of age and his laboratory results showed elevated liver enzymes. Four weeks later, he had fever diagnosed as an initial aggravation, and thus, pyrazinamide at 1200 mg once daily was added to the anti-tuberculosis treatment. Ruxolitinib was discontinued gradually over 4 months. Three months after the commencement of treatment, a follow-up sputum culture was negative for M. tuberculosis and the lower respiratory symptoms and skin nodules were resolved. Five months after treatment, thoracic vertebrae debridement surgery was performed to control his back pain. On post-operation day 5, however, the patient presented with acute heart failure and was diagnosed with takotsubo cardiomyopathy. He died on post-operation day 13.