A 26-year-old pregnant woman was admitted owing to cough for 11 days, fever for 6 days and dyspnea for 2 days at 15 weeks of gestation. She presented with a dry cough 11 days prior to admission, accompanied by profound fatigue and night sweats. After treatment with Chinese patent medicine, the symptoms were temporarily resolved. High fever occurred 6 days prior, with a peak temperature of 39.3 C, accompanied by cough with white sputum. There was no clinical response to symptomatic treatment administered. Her previous symptoms aggravated 2 days prior, with a peak temperature of 40.1 C, along with dyspnea and altered sensorium. There were no chills, loss of consciousness, hemoptysis, or colporrhagia. Chest X-ray showed diffuse bilateral infiltration and nested polymerase chain reaction (PCR) for M. tuberculosis complex in sputum was positive, which was performed in the Maternal and Child Health Hospital. She was then transferred to the medical intensive care unit (MICU) of the Third Affiliated Hospital of Sun Yat-Sen University for isolation and further treatment.
The patient had a past history of Evans syndrome (ES) for 4 years. She regularly took oral corticosteroids (prednisone 20-45mg/day) and had normal hemoglobin and platelet counts. She had no disorders related to the other organs and was a non-smoker. She had no past history of M. tuberculosis infection and any recent travel, tick bites, or poultry contact. Her pregnancy duration was uneventful to date.
On admission to the MICU (day 1), her vital signs were as follows: body temperature, 37.0 C, pulse rate, 120 beats/min, respiratory rate, 40 breaths/min, blood pressure, 140/68 mmHg, and oxygen saturation, 95.0% with breathing 15 L/min of oxygen by venture mask. She was drowsy and appeared to be acutely ill. The diminished breath sounds and wet rales in both lungs were heard on auscultation. There was no audible murmur on cardiac auscultation. Tenderness, hepatomegaly and splenomegaly were not detected. The patient had no neck stiffness. No rash was observed.
Laboratory data upon admission revealed a white blood cell (WBC) count of 13.86 x 109/L with an elevated neutrophil ratio of 94.0% and normal eosinophil ratio, hemoglobin of 101 g/L, and platelet count of 73 x 109/L. The concentration of C-reactive protein (CRP) and procalcitonin was 222.0mg/L and 3.29ng/mL, respectively. The erythrocyte sedimentation rate (ESR) was 47 mm/h. Albumin was 20.8g/L. Globulin was 21.8g/L. Triglyceride level was 1.3 mmol/L. Her lactic dehydrogenase (LDH) level was 568 U/L. The uric acid concentration was 429 micromol/L. Electrolytes, creatinine, aspartate aminotransferase, alanine aminotransferase, total bilirubin and direct bilirubin levels were within normal limits. Even with continuous nasal high flow oxygen therapy, arterial blood gas analysis showed a pH of 7.44, PO2 of 71.0 mmHg, PCO2 of 38 mmHg, oxygenation index of 87.6, and lactate level of 1.0 mmol/L. Coagulation tests demonstrated prothrombin time of 13.7 s, prothrombin activity of 95%, and fibrinogen 5.0 g/L. Serology for respiratory viruses (adenovirus, influenza A virus, influenza B virus, parainfluenza, and respiratory syncytial virus) as well as bacteriological assays (Mycoplasma pneumoniae, Chlamydia pneumonia, and Legionella) were all negative. Tests for cytomegalovirus, Epstein Barr virus, Toxoplasma, rubella virus, herpes simplex virus, HIV, hepatitis A, B, C, and E viruses, dengue virus, malaria, Leptospira, and scrub typhus were also negative. Cryptococcal antigen was negative. The galactomannan and beta-D-glucan tests were both negative. The interferon-gamma release assay was indeterminate. Peripheral blood culture was negative. However, the sputum smear sample was positive for acid-fast bacilli. All the indicators were negative for routine laboratory screening (anti-nuclear antibody, anti-extractable nuclear antigen antibody, and anti-neutrophilic cytoplasmic antibody, et al) for autoimmune diseases. Coombs test was negative (The detailed immunological profile was shown in  Supplementary File 1 ). The counts of CD3, CD4, and CD8 T lymphocytes in blood were 520/mm3, 208/mm3 and 284/mm3 respectively, with a decreased CD4/CD8 ratio of 0.73. After admission, a lumbar puncture showed no abnormalities. There was no evidence in cytology and biochemistry of cerebrospinal fluid supporting the existence of tuberculous meningitis. Chest computed tomography (CT) revealed diffuse infiltration and patchy shadows in both lungs and bilateral pleural effusion ( Figures 1A, B ). Abdominal CT revealed splenomegaly but showed no peritonitis and seroperitoneum.
After admission, the patient was initially administered with non-invasive positive pressure ventilation, anti-tuberculosis therapy (ATT), and a low dose of methylprednisolone (40 mg qd intravenous infusion). The details of ATT were isoniazid (0.8 g qd intravenous infusion), rifampin (0.4 g qd orally), ethambutol (0.75 g qd orally), pyrazinamide (0.5 g TID orally) and moxifloxacin (0.4 g qd intravenous infusion). However, the patient's condition deteriorated rapidly with high fever, acute respiratory distress syndrome (ARDS), pancytopenia, and hyperferritinemia on day 3. The patient was treated with tracheal intubation and mechanical ventilation. Metagenome next-generation sequencing (mNGS) of the bronchoalveolar lavage fluid (BALF) identified 926 of 225958 DNA sequence reads and 195 of 491668 RNA sequence reads corresponding to M. tuberculosis complex, respectively. mNGS of blood identified 48 of 125859 DNA sequence reads corresponding to M. tuberculosis. There was no sequence read corresponding to other potential pathogens (Methods, quality control and detailed results of mNGS were shown in  Supplementary File 2 ). Bone marrow smears showed increased macrophage activity with hemophagocytosis without evidence of leukemia or lymphoma. And there was no evidence of M. tuberculosis in bone marrow ( Figure 2A ). Additional blood tests showed hyperferritinemia (6649 ng/mL, normal range 10-291 ng/mL), low NK cell activity (13.08%, normal value: >=15.1%, tested by flow cytometry) and elevated soluble CD25 levels (5730 pg/mL, normal value: <2400 pg/mL, tested by ELISA). Genetic testing for primary HLH was negative (Detailed result of genetic testing was shown in  Supplementary File 3 ). As the embryo died on day 5, she underwent a medical abortion, and caseating tuberculous granulomas were found in the placenta ( Figure 3 ). Clinical laboratory tests and imaging were performed by the department of laboratory and image center of the Third Affiliated Hospital of Sun Yat-sen University, respectively. mNGS, NK cell activity, level of soluble CD25 and genetic testing for primary HLH were performed and reported by Guangzhou Kingmed Medical Test Center Co., Ltd.
At the most severe moment, the patient was assessed with an acute physiology and chronic health evaluation (APACHE) II score of 32, sepsis related organ failure assessment (SOFA) score of 14, Marshall score of 14 and mortality risk of 85.3%. Following consultation with a multidisciplinary team, a diagnosis of disseminated TB-associated HLH was made. Along with the continuation of four drug ATT regimen, therapy of higher dose of methylprednisolone (80 mg bid intravenous infusion) combined with immunoglobulin (20 g qd intravenous infusion, days 2-10) and plasma exchange (2000 mL each time on days 4 and 8) was administered. The patient responded well to the treatment, with marked improvement in fever and cytopenia ( Figures 4A, B ). She failed to respond to transfusion of platelet initially, then platelet count began to increase spontaneously after combined therapeutic strategy. Elevation of eosinophil ratio was not noted during the treatment. Along with the resolution of hypofibrinogenemia and hyperferritinemia ( Figure 4C ), the concentrations of CRP and interleukin (IL)-6 decreased continuously ( Figure 4D ). The second bone marrow aspiration showed no hemophagocytosis ( Figure 2B ). Her condition improved daily, along with the increase in oxygenation index and improvement in chest CT gradually ( Figures 1C-F ); she was withdrawn from the ventilator on day 10 and was discharged on day 19. Two weeks later, pleural fluid culture revealed M. tuberculosis and was confirmed by Xpert.
Based on the clinical data, the patient was finally diagnosed with disseminated TB-associated HLH, severe pneumonia, type I respiratory failure, severe ARDS, medical abortion, and ES.
The patient was in good condition during the follow-up. Two months after discharge, the standard four-drug ATT was changed to a two-drug continuation phase with isoniazid and rifampin. Methylprednisolone was reduced to 12 mg qd orally. No significant abnormalities were found in WBC, hemoglobin, platelet count, CRP, ESR, LDH, ferritin, and uric acid in the serum.