2 | CASE REPORT
(Case 1) A 7-year-old boy, who developed diffuse papules on his trunk and extremities 1 year previously, was admitted to our hospital due to polydipsia and polyuria. Cranial magnetic resonance imaging (MRI) revealed swelling of the pituitary gland and multiple T2-hyperinFig. 1A). He had no long bone involvement or other classic radiographic findings associated with ECD. Histopathological examination of a papule resected from his waist revealed accumulation of skin dendrocyte-derived histiocytes, which were positive for CD68 and FXIII, and negative for S100, CD1a, CD207 (langerin), and BRAF V600E. Therefore, the patient was diagnosed with systemic JXG.
Although a 1-year LCH-oriented chemotherapy resulted in long-term stabilization of the disease,6 his gait was unstable, and he developed ataxia and cognitive deterioration 7 years after treatment. Cranial MRI revealed widespread T2-hyperintense lesions in the bilateral cerebellar dentate nuclei, a finding similar to typical MRI findings in cases of LCH-associated ND (Fig. 1B). Despite monthly intravenous immunoglobulin (IVIG) therapy, his neurological symptoms worsened gradually. No genomic data were derived from old formalin-fixed paraffin-embedded (FFPE) samples due to the low amount of DNA that could be extracted.
(Case 2) A 1-year-old boy presented with fever, papules on his face, pancytopenia, and hepatosplenomegaly. He had no long bone involvement or other classic radiographic associated with ECD. Cranial MRI revealed no abnormal findings. Histopathological examination of a papule and liver biopsy revealed proliferation of histiocytes, which were positive for CD68 and FXIII, and negative for S100, CD1a, CD207, and BRAF-V600E. He was diagnosed with systemic JXG.
The patient underwent a 1-year LCH-oriented chemotherapy, during which he achieved complete remission. Although he experienced relapse of the skin and bone marrow 1 year after the initial treatment, salvage cladribine monotherapy led to second complete remission. year after the salvage treatment, he complained of frequent falls, and fluid attenuated inversion recovery cranial MRI revealed bilateral hyperintense lesions in the cerebellar dentate nuclei (Fig. 2A). Both his neurological symptoms and radiological findings improved spontaneously (Fig. 2B). Droplet digital polymerase chain reaction and next generation sequence analyses of FFPE samples7,8 failed to detect the somatic mutations frequently found in histiocytic neoplasms, including BRAF, MAP2K1, KRAS, NRAS, CSF1R, and ALK.