PMC10171769_01
FDG PET/CT maximum intensity projection (a), axial (b and d), sagittal (c), and coronal (e) fused images. Metabolically active left L5-S1 sciatic nerve roots (block arrows, image a and e), right trigeminal nerve (arrows, image a-c), and left adrenal (curved arrow, image d) involvements. FDG PET/CT: Fluorodeoxyglucose positron emission tomography-computed tomography
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F1
FDG PET/CT scan revealed avid left adrenal lesion and intense linear avidity in the left L5-S1 nerve root of the sciatic nerve, extending through greater sciatic foramina into the posterior compartment of the upper thigh [Figure 1].
PMC10171769_02
FDG PET/CT maximum intensity projection (a), coronal (b), and axial (c) fused images. Metabolically active linear tracer uptake in right ulnar (arrows, image a and b), right sciatic (block arrows, image a and c), and left obturator (curve arrow, image c) nerves. FDG PET/CT: Fluorodeoxyglucose positron emission tomography-computed tomography
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F2
FDG PET/CT showed a linear avid lesion in the right ulnar nerve, left brachial plexus, and left obturator nerve [Figure 2].
(a) CT-guided biopsy from the right sciatic nerve lesion showed diffuse infiltration by the neoplastic lymphoid population of cells (H and E, x40). (b) The neoplastic lymphoid cells were predominantly large with vesicular nuclei and conspicuous nucleoli exhibiting brisk mitosis (arrows) (H and E, x400). (c) Neoplastic large lymphoid cells were diffusely positive for CD20, confirming the recurrence of DLBCL Diaminobenzidine (DAB, x100). (d) CD3 highlights background nonneoplastic reactive T-lymphoid cells (DAB, x100). (e) MUM-1 showed diffuse nuclear immunoexpression with strong intensity (DAB, x100). (f) BCL6 showed diffuse nuclear immunoexpression with moderate intensity (DAB, x100). CT: Computed tomography, DLBCL: Diffuse large B-cell lymphoma
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F3
Right sciatic nerve biopsy was positive [Figure 3].
PMC10171769_03
FDG PET/CT maximum intensity projection (a), axial (b and c), and sagittal (d) fused images. Metabolically active multiple focal tracer uptake in bilateral neural forminas in the cervical and dorsal spine (Black block arrow, image a). Focal tracer uptake was seen in bilateral trigeminal (white block arrows, images b and c), right hypoglossal (white curve arrow, image c) nerves, and intense tracer uptake in multiple lumbar vertebrae (white arrow, image d). FDG PET/CT: Fluorodeoxyglucose positron emission tomography-computed tomography
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F4
FDG PET/CT scan revealed corroborative to MRI [Figure 4].
(a) CT-guided L3 vertebra and nerve root dural layer core biopsy showed fibro-adipose tissue infiltrated by the atypical lymphoid population of cells. Foci of ischemic necrosis were also seen (arrow) (H and E, x40). (b) Neoplastic lymphoid cells were predominantly large and were admixed with reactive lymphoid infiltrate. Significant mitosis noted (arrow) (H and E, x400). (c) Neoplastic large lymphoid cells were positive for CD79a, confirming the recurrence in a known case of DLBCL. The admixed reactive lymphoid cells were negative (DAB, x200). (d) Neoplastic large lymphoid cells were however negative for CD20 (as the patient had received rituximab) (DAB, x100). (e) Neoplastic large lymphoid cells showed nuclear strong immunoexpression for BCL6 (DAB, x200). (f) Mindbomb E3 ubiquitin protein ligase 1 (MIB)-1 (ki-67) index was 60%, and immunoexpression was seen in large neoplastic lymphoid cells (DAB, x200). CT: Computed tomography, DLBCL: Diffuse large B-cell lymphoma
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F5
L3 vertebra and nerve root dural layer biopsy confirmed recurrence [Figure 5].
PMC10171769_04
FDG PET/CT maximum intensity projection (a), axial (b-e) fused images and T1W contrast-enhanced images (f-i). Focal tracer uptake was seen in bilateral trigeminal (black arrows, image a, b, f and g), bilateral brachial plexus (curved up arrows, image a), left 7th intercostal nerve (white curve arrow, image c), diffuse meningeal thickening (image h), with thickening of the exiting nerve roots in the bilateral lower dorsal and lumbosacral nerve roots (image a, d and i), and lytic lesion with soft tissue along the posterior aspect of left femur midshaft region (white elbow arrow, image e). FDG PET/CT: Fluorodeoxyglucose positron emission tomography-computed tomography
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F6
FDG PET/CT scan showed avid bilateral Vth CN thickening extending into the foramen ovale, with focal meningeal thickening along the left temporal lobe [Figure 6].
PMC10171769_05
FDG PET-CT maximum intensity projection (a), fused sagittal (b), coronal (c) axial (d), and TIW post contrast fat saturated sagittal (e) and coronal (f) images. Metabolically active enhancing linear thickening in sacral canal extending in S1-S3 left sacral foramina (Block arrows). FDG PET/CT: Fluorodeoxyglucose positron emission tomography-computed tomography
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F7
FDG PET/CT also showed linear avid thickening in the left S1 to S3 nerve root region [Figure 7].
PMC10171769_06
FDG PET-CT maximum intensity projection (a), coronal (b-d) fused images. Scan showed metabolically active lymph nodes with fusiform and linear thickening in the left brachial plexus, bilateral ulnar nerve (in arm and forearm, arrows, image a and c), right sciatic nerve and bilateral tibial nerves (block arrows, image a and d). FDG PET/CT: Fluorodeoxyglucose positron emission tomography-computed tomography
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F8
FDG PET/CT showed multiple FDG-avid supra- and infra-diaphragmatic lymph nodes with multiple fusiform and focal linear thickening in the left brachial plexus, bilateral ulnar nerve, right sciatic nerve, and bilateral tibial nerves [Figure 8].