Fig. 2

Imaging and morphologic findings of the index patient. A1-A3: Pulmonary, abdominal and pelvic CT scan shows no sign of infection, absence of hepatosplenomegaly and kidneys with slightly diminished size. A4: Mediastinal window depicts enlarged left axillary lymph node, with the ring-shape nodal necrosis (arrow). B1-B4: US image obtained at the same time as the CT scan shows a somewhat matted, hypoechoic nodal mass at the cervical, supraclavicular, axillary and inguinal sites, with an irregular perinodal border (arrow), suggesting perinodal infiltrates. C1-C2: Bone marrow aspiration and biopsy reveal trilineage hematopoiesis with hemophagocytosis (red circle). C3-C4: Lymph node biopsy finds that left cervical and axillary lymph nodes were filled with CD3⁺CD8⁺ T-lymphocytes surrounded by histiocytes in the necrotizing lesions, which was consistent with a diagnosis of KD.