case_images: PMC8767649_01
case_images: Patient's chest radiograph demonstrating bilateral diffuse infiltrates consistent with acute respiratory distress syndrome.
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case_images: She became progressively hypoxemic with serial chest X-rays (Figure 1) showing bilateral interstitial infiltrates consistent with ARDS and ultimately required intubation.
case_images: Wright stain aspirate smear of bone marrow. Histiocytes are noted to be increased (black arrows) demonstrating evidence of hemophagocytosis, with one histiocyte showing ingestion of an immature granulocyte (red arrow).
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case_images: Due to suspicion of HLH, a bone marrow biopsy was performed, which showed normocellular marrow with myeloid predominance, mild granulocyte atypia, and increased histiocytes (Figure 2).
case_images: H&E and CD163 immunohistochemical stain of core bone marrow biopsy.. H&E stain showing normocellular marrow for age (approximately 30-35% cellularity). CD163 stain highlighting numerous histiocytes throughout the marrow space.
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case_images: CD163 immunostaining of the core biopsy revealed markedly increased histiocytes with some cells showing ingested cellular material, which is consistent with HLH (Figure 3).