Plasmacytoma of the skull (MRI)
Headache, depression and insomnia. PMHx Multiple myeloma and chronic neutrophilic leukaemia. Skull lesion ?haemangioma.
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3.9 x 2.8 x 3.6 cm mass fifth erodes both inner and outer tables of the left parietal bone. This is T1 isointense to muscle on T2 hyperintense with diffuse but slightly heterogeneous enhancement. Some low signal linear regions within largely correlate with residual bony spicules on CT. The lesion results in minor local mass effect upon underlying parietal gyri but there is no brain parenchymal involvement. Lesion lies in close proximity but does not immediately abut the otherwise normal superior sagittal sinus.
The smaller lytic lesion involving outer table only appreciated on CT (see this case) shows a small lesion of similar signal and enhancement characteristics. No direct continuity appreciated between the 2 lesions. No other lesion identified. Sulcal and ventricular pattern is normal for age. No significant abnormal parenchymal signal or enhancement.
In this clinical setting, plasmacytoma/myeloma deposits are most likely. No definite imaging features to suggest haemangioma.
The patient went on to have a biopsy.
The sections show a densely cellular malignant infiltrate, forming sheets and aggregates. It invades in-between bony trabeculae. The tumour cells are plasmacytoid in appearance. They have enlarged round nuclei, clumped chromatin, occasional perinuclear hofs and moderate amounts of eosinophilic cytoplasm. There is no amyloid in the background. The tumour cells are CD138 positive. Scattered cells are lambda light chain positive. Kappa light chain is negative. CD3 and CD20 are also negative. The features are those of multiple myeloma.
This is the MRI of the same patient who has this CT of the brain (one day I will combine them).