case_images: PMC9659946_01
case_images: Imaging of the patient. CT (A, B), MRI (C), and PET (L) revealed multiple enlarged lymph nodes in the mediastinum and axilla with elevated glucose metabolism. After remission, CT (D, E) and PET (M) showed smaller lymph nodes than before and decreased glucose metabolism. Before treatment, PET (H) depicted multiple lymph node enlargements and tissue involvement with abnormally increased glucose metabolism. After remission, PET (I) revealed a significant reduction in the original lymph node and tissue lesions and decreased glucose metabolism. After remission, PET (J, L) indicated elevated FDG metabolism in the posterior nasopharyngeal wall and central bone marrow (K, M), suggesting normal FDG metabolism. MRI (F, G) indicated edema around the dorsal extensor tendons of the 2nd to 5th metacarpals of the right hand and soft tissue swelling around the right wrist. PET (N) depicted increased liver volume. Moreover, repeat PET (O) after remission indicated increased liver volume and diffused hypodensity of the liver parenchyma. CT, computed tomography; MRI, magnetic resonance imaging; PET, positron emission tomography.
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case_images: Magnetic resonance imaging (MRI) and computed tomography (CT) ( Figures 1A-E ) showed multiple enlarged lymph nodes of the mediastinum and the axilla. MRI ( Figures 1F, G ) indicated edema around the dorsal extensor tendons of the 2nd to 5th metacarpals in the right hand and soft tissue swelling around the right wrist. Positron emission tomography (PET) ( Figures 1H-O ) depicted multiple systemic enlarged lymph nodes coupled with abnormally high glucose metabolism, hepatosplenomegaly, significant myeloproliferative neoplasm, and infiltrated connective muscle tissue.
case_images: Bone marrow cell morphology of the patient. (A) The proliferation of bone marrow is active; (B) the presence of phagocytic cells; (C) severely diminished nucleated cell proliferation; (D) active bone marrow nucleated cell proliferation.
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case_images: Figure 2A ) on the second day of admission suggested that the proliferation of bone marrow was active. Flow cytometry analyzed 10.9% of the mature lymphocyte population in the bone marrow, with 0.2% of the CD5+CD10- mature clonal B-lymphocyte population being visible. Bone marrow cell morphology ( Figure 2B ) revealed phagocytic cells. Three weeks after the start of chemotherapy, bone marrow cell morphology ( Figure 2C ) indicated severe hypoplasia of bone marrow nucleated cells without phagocytic cells. Three days before discharge, bone marrow cell morphology ( Figure 2D ) revealed active proliferation of myeloid nucleated cells, normal morphology of all the cells, and no phagocytic cells.
case_images: Brain imaging of the patient. T2WI (A, B) showed a high brainstem density and thalamus density (red circle). Brain T2WI (C, D) 2 weeks after ANE diagnosis indicated brainstem edema and typical "concentric circles" (red circles) within the thalamus. T2WI (E, F) after remission indicated the disappearance of edema and damage in the thalamus and brainstem. T2WI, T2-weighted MRI; PET, positron emission tomography; ANE, acute necrotizing encephalopathy.
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case_images: MRI ( Figures 3A, B ) showed high-intensity brainstem and thalamus areas on T2-weighted images (T2WI), which indicated edema. After 2 weeks, the MRI ( Figures 3C, D ) still depicted symmetrical brain damage, and the thalamic damage revealed the typical "concentric circle" sign. Necrotic lesions were still visible on brain MRI ( Figures 3E, F ) but significantly improved from the previous examination.
case_images: Flowchart of the patient disease progression and clinical treatments. HLH, hemophagocytic lymphohistiocytosis; ANE, acute necrotizing encephalopathy.
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case_images: The patient's disease progression and treatment flow chart are shown in  Figure 4 .