Involvement of cranial vault in Hodgkin lymphoma

Clinical History

The patient presented with nodular sclerosis (grade II) Hodgkin disease stage IIA. After 5 months the patient presented with swelling over the right parietal bone and cervical lymphadenopathy without "B" or other symptoms.

Imaging Findings

The patient presented with nodular sclerosis (grade II) Hodgkin disease stage IIA (bulky disease of the mediastinum). He had a complete remission after treatment with nitrogen mustard, vincristine, procarbazine and prednizon (MOPP) and radiotherapy.

After 5 months the patient presented with swelling over the right parietal bone and cervical lymphadenopathy without "B" or other symptoms. The laboratory tests showed mild normochromic, normocytic anaemia and a high erythrocyte-sedimentation rate (ESR).

CT of the brain showed a large hyperdense scalp lesion involving the right frontoparietal region (Fig. 1). The lesion extended through the bony calvarium to the epidural space. An intraaxial hypodense area corresponding to peritumoral oedema in the frontal lobe was depicted. The cranial vault showed a slight osteolysis in the region of the subcutaneous mass.

MR images revealed a large mass in the scalp of the right frontoparietal region with an epidural component. The mass was isointense on TI-weighted images. On T2-weighted images the epidural component as well as part of the scalp mass was hypointense. Hyperintense white matter oedema in the frontal area was also depicted on T2-weighted images. After the administration of paramagnetic agent the lesion showed strong enhancement. Linear meningeal enhancement on both sides of the epidural mass was also noted (Fig. 2).

Biopsy from the soft tissue mass of the right parietal area showed infiltration with Reed Stenberg cells, lymphocytes, histiocytes, eosinophils, plasma cells and polymorphs. The findings were compatible with Hodgkin's disease, nodular sclerosis type. Bone marrow examination was normal. The patient received combination chemotherapy (dexa-Beam) and involved field radiation therapy (3500 rads). Two months after treatment the patient was in partial remission.

A post-treatment follow-up MR examination revealed shrinkage of the mass, both the scalp and epidural components, with residual linear meningeal enhancement. Complete resolution of the white matter oedema was also noted (Fig. 3).

Discussion

Cranial vault involvement on lymphomas although rare, is most commonly associated with non-Hodgkin disease. The involvement of the bone in Hodgkin's lymphomas usually occurs in the late stages of the disease and is indicative of widespread, aggressive disease with a poor prognosis [1]. Secondary involvement of the brain or meninges is an uncommon complication of HD occurring in 0.2-0.5% of all cases in advanced stages. The involvement of the epidural space is usually secondary to extension of the tumour from contiguous calvarial involvement [2]. This explains the extension of a scalp mass both into epidural space as well as to subcutaneous soft tissue. Rarely HD may arise primarily in the dura or cranial vault [3]. The initial symptoms and signs of lymphoma in the skull include a painless scalp lump, headache due to bony destruction or tumour infiltration of the meninges, seizures, and focal neurological deficits resulting from the cortex infiltration [4,5].

The imaging findings are nonspecific. In the majority of reported cases of skull lymphomas, the mass is hyperdense on unenhanced CT scan and shows marked enhancement on post-contrast studies. Destruction of the bone may not be seen in some cases, because of the characteristic permeating growth pattern of lymphoma with a large soft tissue component and very little bone destruction. The bone window setting is useful in depicting tiny lytic lesion of the bony calvarium.

MR provides direct multiplanar imaging, thus, it is ideal for detecting extracerebral tumour deposits in the subdural or epidural space. Most often the densely cellular deposits of lymphoma do not show high signal intensity on T2-weighted images and typically remain hypo- to isointense on all pulse sequences. Post-contrast T1-weighted images show dense either homogeneous or inhomogeneous enhancement. Linear dural enhancement is usually seen on both sides of the dural mass [1-4]. Although this type of linear enhancement along the dura mater, referred to as the dural tail, has been reported as an important finding in the diagnosis of meningioma, it is also observed in other conditions involving the dura mater such as glioma, brain metastasis, sarcoidosis, and lymphoma.

The cause of white matter oedema associated with extra-axial tumours is unknown, although various theories have been proposed, such as active fluid production by the tumour, a disrupted blood-brain barrier, or the influence of vascular endothelial growth factor.

The differential diagnosis of a cranial vault mass with an epidural component includes osteomyelitis, secondary metastatic lesion, meningioma, solitary plasmocytoma, and reparative granuloma.

Although involvement of the cranial vault is a rare complication of Hodgkin's lymphoma, it must be suspected in patients with scalp pain or soft tissue oedema.

Differential Diagnosis List

Final Diagnosis

Involvement of cranial vault in Hodgkin lymphoma

URL:	https://www.eurorad.org/case/1818
DOI:	10.1594/EURORAD/CASE.1818
ISSN:	1563-4086