CASE REPORT
A 6-year-old boy with fever was suspected of having Mycoplasma pneumoniae infection and was prescribed acetaminophen and clarithromycin in the clinic 7 days before admission. He had no previous medical or family history. In addition, there was no history of drug allergy or exposure to suspected drugs before disease onset. At night, erythema multiform appeared on the patient’s face and trunk. Three days before admission, he was diagnosed with SJS at a general hospital based on skin findings. Although he was administered prednisolone (2.0 mg/kg/day), his erythema gradually expanded and developed dyspnea. The patient was transferred to our hospital for further intensive care.
Upon admission, his vital signs were as follows: body temperature, 37.3 °C; blood pressure, 86/52 mmHg; heart rate, 86 beats/min; respiratory rate, 36 breaths/min; and oxygen saturation, 90% with O2 at 8 L/min via an oxygen mask with a reservoir bag. Retractions appeared immediately below the neck and under the breast. Subcutaneous emphysema was observed in the cervical and supraclavicular fossae. Chest examination revealed coarse crackles, decreased breathing sounds, and bilateral expiratory wheezing. No hyperemia or erosion was found in the conjunctiva of the eyeball, bloody scabs were found on the lips, and no redness or erosion was found in the oral cavity. The body surface area of blisters or erosions was less than 10%, and that of erythema was 25% (Fig. 1A ). Laboratory examination further revealed the following findings: white blood cell, 5,800 /µL (neutrophils 69.6%, lymphocytes 19.3%, and eosinophils 0%); red blood cells, 482×104 /µL; hemoglobin 13.2 g/dL; platelet, 35.2×104 /µL; total-bilirubin, 7.0 mg/dL; aspartate aminotransferase, 304 U/L; alanine aminotransferase, 372 U/L; lactate dehydrogenase, 614 U/L; ferritin, 615 ng/mL; soluble interleukin-2 receptor, 779 U/mL; Krebs von den Lungen 6 (KL-6), 953 U/mL; and antinuclear antibody titer, 1:40. The drug lymphocyte stimulation test (DLST) was positive for acetaminophen (H-thymidine, 905 cpm; stimulation index, 274%) and negative for clarithromycin (H-thymidine, 226 cpm; stimulation index, 114%).  Moreover, the loop-mediated isothermal amplification (LAMP) assay for M. pneumoniae was negative, and there was no increase in antibody titer. Chest radiography revealed subcutaneous emphysema, bilateral mediastinal emphysema, and decreased permeability in the bilateral middle and lower lung fields (Fig. 1B ).
Based on these findings, we diagnosed severe SJS due to acetaminophen with mediastinal/subcutaneous emphysema. We also administered high-dose immunoglobulin (0.5 g/kg/day, for 5 days) and methylprednisolone pulse therapies (1 g/day for 3 days/week), resulting in an improvement in the eruption. However, his respiratory failure persisted, and the chest CT showed a ground-glass-like shadow (Fig. 1C ). We diagnosed acute respiratory distress syndrome (ARDS), and cyclosporine (3.0 mg/kg/day) was added to the treatment regimen on day 9. Artificial respiration with tracheal intubation was initiated on day 13. Persistent progressive respiratory failure, veno-venous extracorporeal membrane oxygenation, and plasmapheresis were introduced on day 44. On day 51, left hemopneumothorax developed, and thoracoscopic hemostasis and lung biopsy were performed. Pathological examination of the pulmonary tissue revealed the diffuse alveolar injury, confirming the diagnosis of diffuse alveolar damage (DAD) (Fig. 1D ). Although we performed various multidisciplinary treatments, his lung lesions showed poor treatment responsiveness, and he died on day 90.