case_images: PMC11304403_01
case_images: (a, b) Post-contrast coronal image shows intracranial extension of the skull base tumour causing mass effect and compression of the left lateral ventricle (yellow arrow). It invades the central skull base and sphenoid sinus (red arrow), extending inferiorly into the masticator space (purple arrow) and nasopharynx (blue arrow). There is left-sided proptosis (green arrow). (c) Post-contrast axial image shows the extent of the intracranial component (black arrow) of the tumour compressing the midbrain (orange arrow) and extending into the suprasellar cistern (yellow arrow). No cerebral oedema. (d-f) Pre-contrast, post- contrast and bone window images in the same axial plane. The tumour is pre-contrast dense (d) and avidly enhances (e). It involves the left sinonasal passage (blue arrow), left masticator space (purple arrow) and the left pterygopalatine fossa (red arrow). Erosion of the bone (f) including the pterygoid plates (red arrow), clivus (yellow arrow) and petrous apex (green arrow).
case_images: SAJR-28-2883-g001.jpg
case_images: PMC11304403_01_SAJR-28-2883-g001.jpg
case_images: F0001
case_images: The radiodense material within the matrix was in keeping with scattered bone fragments (Figure 1).
case_images: Bone window (a) and magnified bone window (b) of the left temporal bone show the expansion of the medullary cavity and unusual periosteal reaction (red arrow) that is perpendicular to the distorted cortex and has an irregular curled and haphazard construction reminiscent of a crown of thorns (c).
case_images: SAJR-28-2883-g002.jpg
case_images: PMC11304403_01_SAJR-28-2883-g002.jpg
case_images: F0002
case_images: (a-c) Coronal pre-contrast T1-weighted (T1W), post contrast T1W fat saturation (FS) and T2-weighted (T2W) FS at the same level. The trans-spatial base of skull tumour (red arrow) is hyperintense to muscle on T1W (a) and T2W FS (c) and avidly enhances on post contrast T1W FS (b). Invasion of the left cavernous sinus is demonstrated (blue arrow). (d-e) No restricted diffusion (red arrow) on axial diffusion-weighted imaging (DWI) (d) and apparent diffusion coefficient (ADC) (e). The tumour is shown to extend into the extraconal compartment of the left orbit (yellow arrow) with resultant proptosis of the left globe (green arrow).
case_images: SAJR-28-2883-g003.jpg
case_images: PMC11304403_01_SAJR-28-2883-g003.jpg
case_images: F0003
case_images: T2-weighted (T2W) and fluid-attenuated inversion recovery (FLAIR) images when compared to muscle and avidly enhancing on T1W-post-gadolinium images. The tumour showed no restricted diffusion on apparent diffusion coefficient (ADC)/diffusion-weighted imaging (DWI) (Figure 3). The aggressive nature of the tumour was further highlighted by the intracranial extent with cavernous sinus infiltration (Figure 3).
case_images: (a, b) 18F-FDG positron emission tomography (PET)/CT demonstrates the avid left skull-base tumour (yellow arrow) (a) and the avid focus in the right posterior 8th rib (red cross hairs) (b).
case_images: SAJR-28-2883-g004.jpg
case_images: PMC11304403_01_SAJR-28-2883-g004.jpg
case_images: F0004
case_images: Furthermore, avid uptake in a lytic lesion in the 11th thoracic vertebral body was demonstrated (Figure 4).
case_images: (a-d) Many cells exhibited an eccentrically located nucleus, abundant amphophilic cytoplasm, and a distinctive paranuclear hof, which gave rise to a clock face appearance (a). The lymphoproliferative neoplasm displayed negative staining for CD20, CD3, and CD56 (not shown). Epstein-Barr encoding region (EBER) in situ hybridisation yielded a positive result (b). The Ki67% was interpreted to be 20% - 30% (c), and plasma cell markers were positive, including CD138 (d), multiple myeloma oncogene-1 (MUM1), and VS38c. Kappa and Lambda in situ hybridisation revealed a Lambda light chain restriction, consistent with a neoplastic proliferation of plasma cells (not shown).
case_images: SAJR-28-2883-g005.jpg
case_images: PMC11304403_01_SAJR-28-2883-g005.jpg
case_images: F0005
case_images: A solitary plasmacytoma of the bone was favoured, but plasma cell myeloma needed to be excluded (Figure 5).
case_images: (a, b) Post-therapeutic post-contrast coronal CT head at 5 months (a) and 9 months (b) after diagnosis. Post-chemotherapy image (a) shows a decrease in the volume of the base of skull plasmacytoma (red arrow). Post-radiation image (b) shows a radiological response with no residual enhancing tumour (red arrow). There is post-therapeutic left temporal lobe volume loss (yellow arrow).
case_images: SAJR-28-2883-g006.jpg
case_images: PMC11304403_01_SAJR-28-2883-g006.jpg
case_images: F0006
case_images: A decrease in volume of the base of skull plasmacytoma on follow up CT imaging was in keeping with a partial response to therapy (Figure 6a). The patient received a further 15 fractions of radiotherapy to the base of skull mass which resulted in a complete radiological response with no appreciable mass on follow up imaging (Figure 6b).