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case_images: The role of head MRI in the evaluation of therapy response.. Notes: (A) T2W image shows left temporal bone involvement of LCH (white arrow). (B) This lesion shows inhomogenous diffusion restriction (black arrow) on the diffusion-weighted image. (C and D) Normal appearance of the left temporal area after the initial chemotherapy on T2W and diffusion-weighted images. (E and F) Signal abnormality in the left temporal area on the T2W (white arrow) and diffusion-weighted (black arrow) images.. Abbreviations: LCH, Langerhans cell histiocytosis; MRI, magnetic resonance imaging.
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case_images: Thanks to the effectivity of the therapy, rapid regression of the skull masses was detectable in the beginning (Figure 1C and D), but in the fourth month of chemotherapy, hepatosplenomegaly, hypalbuminemia, serious pancytopenia occurred, the activity of the left frontal bone lesion came back (Figure 1E and F), and the skin symptoms flared up.
case_images: Skull lesion in LCH.. Notes: (A) Hematoxylin-eosin stain. Majority of the cells have coffee bean-shaped nuclei with open chromatin pattern and nuclear membrane grooves. (B) Strongly positive CD1a immune reaction, which is specific for LCH.. Abbreviation: LCH, Langerhans cell histiocytosis.
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case_images: B). Based on the patient history, physical findings, and imaging studies, LCH came up as a possible diagnosis with skin and multifocal bone involvement, which was confirmed histologically: the biopsy specimen from one of the skull masses was histologically composed of CD1a- and S100-positive mononuclear cells with coffee bean-shaped nuclei, eosinophil granulocytes, and multinucleated giant cells (Figure 2A and B).
case_images: Massive bone marrow infiltration with ECD (original magnification).. Notes: (A) Hematoxylin-eosin stain. The marrow spaces are extensively engaged by foamy macrophages. (B) S100 immune reaction. The immune phenotype of macrophages is consistent with the phenotype of the conventional tissue histiocytes (CD68 positive, S100 negative). S100 is a highly sensitive but a nonspecific marker of Langerhans cells, therefore a good marker for screening Langerhans cells, or exclude Langerhans cell origin of a tumorous proliferation.. Abbreviation: ECD, Erdheim-Chester disease.
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case_images: These macrophages had water clear wide cytoplasm and rounded nuclei (Figure 3A and B).
case_images: Plain radiograph of the knees (A) before and (B) after vemurafenib treatment.. Notes: (A) Bilateral, symmetric, irregular sclerotic changes in the metaphysis of the bones. (B) Normal bone structure with a radiolucent band and small cystic lesions next to the epiphyseal plates.
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case_images: On plain radiograph of the painful knees, symmetric osteosclerosis could be seen (Figure 4A). Our findings reveal that the histological disappearance of the disease from the bone marrow can last for several months; however, the radiological improvement takes a couple of weeks/month (Figure 4B), and the positive clinical response is the first indicator of the effective treatment.
case_images: Coronal T2W image of the spine shows very low signal intensity of the bone marrow that is specific for ECD.. Abbreviation: ECD, Erdheim-Chester disease.
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case_images: Interestingly, low signal intensities could be seen in all visualized bones (not only in the long bones) on every MRI sequence (Figure 5).
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