Plasmacytoma - cavernous sinus

Case contributed by A.Prof Frank Gaillard

Presentation

CN III and IV palsy on the right.

Patient Data

Age: 56-year-old
MRI

MRI Brain

A rounded lobulated mass is centred on the right cavernous sinus, posterior to the carotid, eroding the adjacent bone, and displacing the pituitary, from which it is separate, slightly towards the left. It is of intermediate T1 and T2 signal, with a rapid and vivid contrast enhancement, and no associated dural thickening. No flow voids within. ADC values are relatively depressed (800 x 10^-6 cm^2/s) suggest this is a quite cellular tumour. The mass has no suprasellar extent, and the optic nerves and chiasm are unremarkable. Flow voids of the carotids and other intracranial vessels appear unremarkable. 

Anteriorly, arising from the left side of the falx, and only partially imaged is an extra-axial mass with a prominent dural tail. It is also lobulated although it has a different signal intensity on T2 and different ADC values. It is more likely a separate incidental meningioma rather than representing two of the same type of lesion. 

Conclusion: Differentials include multiple myeloma, lymphoma and metastases. A meningioma is and a possibility, although the morphology is atypical for this. A neurogenic tumour (schwannoma) is another possibility of a signal intensity and diffusion restriction would also be atypical for this. 2. Left para falcine extra-axial mass may represent a 2nd instance of the same pathology, although signal characteristics are somewhat different and more likely it represents a coincidental meningioma.

Pathology

MICROSCOPIC DESCRIPTION: 1-2. The sections show fragments of a densely hypercellular tumour. This consists of a diffuse sheeted arrangement of moderately pleomorphic plasma cells. An occasional mitotic figure is identified. No areas of necrosis are seen. Immunohistochemistry shows strong staining in tumour cells for CD138, CD20 and BOB-1. There is lambda light chain restriction. Scattered CD45+ lymphocytes are admixed with the atypical plasma cells. No staining for PAX 5, epithelial membrane antigen (EMA), CD56 or OCT-2 is seen in tumour cells. The Ki-67 proliferation index is approximately 40%. The features are of plasmacytoma/myeloma. 

DIAGNOSIS: Pituitary lesion: Plasmacytoma/myeloma

Case Discussion

This case was histologically proven to be a plasmacytoma.

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Case information

rID: 48750
Case created: 22nd Oct 2016
Last edited: 31st Mar 2017
Inclusion in quiz mode: Included

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