Lymphoma of the skull

Case contributed by Assoc Prof Frank Gaillard

Presentation

Headache.

Patient Data

Age: 65 years
CT

A large hyperdense mass that has a large intracranial component and a smaller extracranial component preserving the intervening bone. Extensive edema and mass effect. No hyperostosis or bony destruction (best seen on bone windows that are not, unfortunately, available). 

MRI

A large intracranial lesion is present within the right frontal region that crosses bone with an associated extracranial component that involves the right temporalis muscle and extends inferiorly into the infratemporal fossa.

The lesion is isointense to grey matter on both T1 and T2, and demonstrates heterogeneous peripheral and central regions of enhancement. At the medial and posterior margins of the lesion, T1 hyperintensity measuring up to 9 mm in depth with associated susceptibility artefact is in keeping with surrounding hemorrhage. Further regions of susceptibility artefact also noted within the medial and inferior portions of the lesion. More medially is an additional region of peripheral contrast enhancement surrounding an area of "cystic" change. Dural tails are present.

Extensive surrounding T2/FLAIR hyperintensity, with associated localized mass effect and effacement of the right lateral ventricle, with midline shift to the right.

The right frontal bone demonstrates slightly increased T1 signal and decreased T2 signal.

Both the intra and extracranial lesions demonstrate marked diffusion restriction. MR spectroscopy is non-specific, especially given the extensive susceptibility artefact. Mildly elevated CBV is noted, similar to adjacent grey matter.

No other intracranial lesions identified.

Conclusion:

Solitary large right frontal intracranial hemorrhagic lesion involving bone, and with an extracranial component, is most likely extra-axial (either bone or dura) in origin. Although this lesion is not entirely typical for a particular diagnosis, lymphoma or an atypical/anaplastic meningioma (highly cellular). Hemangiopericytoma, metastasis, and primary sarcoma are other possibilities. 

Case Discussion

The patient went on to have a core biopsy of the scalp component.

Histology:

Sections show skeletal muscle extensively replaced by a malignant lymphoid infiltrate. The medium-sized lymphoid cells are arranged in diffuse sheets with no germinal centers seen. Tumor cells contain scant cytoplasm with angulated hyperchromatic nuclei and inconspicuous nucleoli. No Reed Sternberg cells are seen.

Immunohistochemical results show tumor cells stain:

  • CD10: positive
  • CD20: positive (focal)
  • BCL2: positive
  • BCL6: positive
  • MUM1: positive
  • CD3, CD5, CD23 and CyclinD1: negative

The Ki67 proliferation index is 80%.

FINAL DIAGNOSIS: CD10-positive diffuse B-cell lymphoma with high proliferation index, consistent with transformed follicular lymphoma.

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Case information

rID: 66065
Published: 22nd Jun 2019
Last edited: 16th Dec 2019
Inclusion in quiz mode: Included

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