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case_images: (A) MRI-scan (T2-TSE) at diagnosis showing the abdominal tumor, pulmonary metastases (indicated with an arrow) and a metastasis in the right proximal femur (indicated with an arrow), (B) MRI-scan of the brain (T1) at diagnosis, (C) after start of neurological symptoms (T1-gadolinium), showing extensive leptomeningeal metastases (indicated with an arrow) and (D) CT-scan (with ultravist contrast) shortly before death of the patient.
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case_images: An MRI-scan revealed a tumor of the left kidney with several pulmonary metastases and skeletal lesions, suspicious for metastases ( Figure 2A ). An MRI of the brain showed no abnormalities ( Figure 2B ) and bone marrow testing showed no metastases. Imaging (by MRI and CT-scan) of the brain showed new leptomeningeal lesions ( Figures 2C, D ) that could not be biopsied.
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case_images: (A) MRI-scan (T2-TSE) at diagnosis showing the abdominal tumor, (B) [123I]mIBG-scan and (C) FDG-PET at diagnosis and (D) RT-qPCR neuroblastoma mRNA marker-panel results at diagnosis (Y-axis, normalized mRNA expression noted as Ctmarker - CtGUSB; green BM infiltration, orange PB infiltration). Dashed line indicates separation of positivity.
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case_images: MRI ( Figure 3A ) showed a retroperitoneal tumor extending into the right suprarenal area, with locoregional lymph node involvement and a potential skeletal metastasis in the S1 vertebra. On [123I]mIBG imaging ( Figure 3B ) there was heterogeneous [123I]mIBG uptake of the primary tumor, with large [123I]mIBG negative parts of the primary tumor and locoregional lymph node metastases. Because of the heterogeneous [123I]mIBG uptake, an [18F]FDG-PET CT was performed ( Figure 3C ), confirming all lesions on [123I]mIBG imaging plus identifying additional skeletal lesions, as suspected on the MRI. In addition, RT-qPCR was performed on diagnostic BM and PB samples using the neuroblastoma MPX-panel, which came back positive for mRNA markers CHRNA3 and GAP43 (Figure 3D).
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case_images: (A) Axial CT-scan (soft tissue setting) at diagnosis showing the primary tumor (indicated with an arrow) and (B) coronal CT-scan (lung setting) at diagnosis showing the pleural effusion.
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case_images: A CT-scan showed multiple masses of the rib, vertebrae and pleura, and a filled right hemithorax (pleural effusion) with a mediastinal shift and deviation of the trachea and left main bronchus ( Figure 4 ).
case_images: (A) MRI-scan (T2 weighted) at diagnosis showing the abdominal and enlarged liver, (B) after treatment (MRI after gadolinium injection) showing gadolinium enhancement of the minimal rest tumor (indicated with an arrow and circle) and (C) RT-qPCR neuroblastoma mRNA marker-panel results at diagnosis (left Y-axis, normalized mRNA expression noted as Ctmarker - CtGUSB; green BM infiltration, orange PB infiltration) and ddPCR MYCN amplification-assay (right Y-axis, ratio MYCN/NAGK, blue hexagon).
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case_images: MRI showed a small tumor in the right adrenal gland with massive liver infiltration, resulting in a very large liver that extended into the pelvis ( Figure 5A ). After chemotherapy, only a very small (8x10 mm) calcified primary tumor lesion remained ( Figure 5B ). RT-qPCR of BM and PB samples at diagnosis showed detection of all neuroblastoma mRNA-markers, including the neuroblastoma-specific marker PHOX2B ( Figure 5C ). No amplification was detected ( Figure 5C ), and a non-high risk neuroblastoma was diagnosed.
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case_images: (A) Ultrasound and (B) [18F]FDG-PET at diagnosis showing the tumor in the left forearm, (C) bone marrow aspirate at diagnosis (63x enlarged) and (D) RT-qPCR rhabdomyosarcoma mRNA marker-panel results at diagnosis (Y-axis, normalized mRNA expression noted as Ctmarker - CtGUSB; green BM infiltration). Dashed line indicates separation of positivity.
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case_images: Imaging by [18F]FDG-PET showed a soft tissue tumor without metastases ( Figures 6A, B ). MyoD1 staining (heterogeneously expressed in embryonal rhabdomyosarcoma) was considered ambiguous in the bone marrow aspirate ( Figure 6C ). No tumor invasion was detected ( Figure 6D ), and the patient was diagnosed with non-metastatic rhabdomyosarcoma.
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case_images: Potential applications of liquid biopsy components.
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case_images: As shown in  Figure 7D , RASSF1A-M stayed positive throughout and BM RT-qPCR became positive at immunotherapy, followed by the PB RT-qPCR.
case_images: (A) [123I]mIBG scintigraphy before [131I]mIBG-treatment, (B) 3-day post [131I]mIBG-therapy scan (C) [18F]FDG-PET-scan after [131I]mIBG-treatment and (D) RT-qPCR neuroblastoma mRNA marker-panel results (left Y-axis, percentage infiltration as calculated by IMR32; green triangles BM infiltration, orange circles PB infiltration) and ddPCR RASSF1A methylation-assay (right Y-axis, copies hypermethylated RASSF1A per mL plasma, blue squares). Dx, diagnosis; nCT 1L, after n courses in first line therapy; nCT 2L, after n courses in second line therapy; IT-0, before GD-2 immunotherapy; IT-3, after 3 cycles of GD-2 immunotherapy; IT-6, after 6 cycles of GD-2 immunotherapy; R, relapse; PD, progressive disease. Green block indicates first line treatment, red block indicates treatment for relapsed disease.
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case_images: During relapse treatment, [123I]mIBG imaging showed progressive disease for which he was treated with [131I]mIBG therapy ( Figure 7A ). After [131I]mIBG therapy ( Figure 7B ), he suffered from pancytopenia despite autologous hematopoietic stem cell reinfusion and severe hemorrhagic cystitis for which he received continuous bladder irrigation through a urinary catheter. This demonstrated diffuse bone marrow activation, reduced uptake in regions with known skeletal metastases and an enhanced liver uptake ( Figure 7C ). As shown in  Figure 7D , RASSF1A-M stayed positive throughout and BM RT-qPCR became positive at immunotherapy, followed by the PB RT-qPCR.