J Neurosurg 108:1018–1020, 2008

Non-Hodgkin lymphoma of the cranial vault
with retrobulbar metastasis mimicking a
subacute subdural hematoma
Case report
SANG-HOON YOON, M.D.,1 SUN HA PAEK, M.D., PH.D.,1 SUNG-HYE PARK, M.D., PH.D.,2
DONG GYU KIM, M.D., PH.D.,1 AND HEE-WON JUNG, M.D., PH.D.1
Departments of 1Neurosurgery and 2Pathology, Cancer Research Institute, Seoul National
University College of Medicine, Seoul, Korea

PPrimary skeletal non-Hodgkin lymphoma is rare. The authors report a case of a small lymphocytic B-cell lymphoma
of the skull occurring in a 53-year-old man who presented with right-hand apraxia. Initial computed tomography and
magnetic resonance imaging revealed a hematoma-mimicking lesion in the left frontoparietal subdural area. A frontotemporoparietal craniectomy and biopsy procedure yielded a diagnosis of small lymphocytic B-cell lymphoma, with a
metastatic nodule in the retrobulbar area. Three years after undergoing radiation therapy and surgery, the patient has
shown neurological improvement without systemic dissemination of the malignancy. The lesion in this case was misdiagnosed as a subdural hematoma, and shows the importance of including lymphoma in the differential diagnosis of subdural mass lesions. (DOI: 10.3171/JNS/2008/108/5/1018)
KEY WORDS • lymphocytic B-cell lymphoma • non-Hodgkin lymphoma •
retrobulbar metastasis • subdural hematoma

P

RIMARY skeletal NHL is rare, occurring in only 1 in

20 cases of lymphoma; of these rare cases, . 75%
originate in the pelvis and limbs.11 A primary NHL of
the skull is exceedingly rare.1,3 The authors report on a
patient found to have NHL of the cranial vault with a retrobulbar metastasis that mimicked a subacute subdural hematoma during preoperative radiological examination.
Case Report

History and Examination. This 53-year-old man without any history of head trauma presented to the emergency
department with a 10-day history of right-hand apraxia.
The patient had a history of pulmonary tuberculosis that
had been cured after he received antituberculosis medication for 6 months. Laboratory test results (complete blood
count, serum chemistry, and urinalysis) were within normal
limits, the patient was not immunocompromised, and was
HIV negative. The preoperative radiological diagnosis was
a left frontoparietal subdural hematoma based on CT scans
and MR images (Fig. 1).
Operation and Postoperative Course. We attempted to
perform frontal and parietal bur hole trephination, but the
liquefied hematoma was not evacuated from the subdural space. Instead, a hypervascular, firm mass lesion was
found. A frontotemporoparietal craniectomy was extended
from the bur holes. After removal of sponge-like denatured
Abbreviations used in this paper: CT = computed tomography;
MR = magnetic resonance; NHL = non-Hodgkin lymphoma.

1018

skull vault, a granulated tissuelike tough texture filled the
epidural and subdural space, with unusual dural thickening.
The subdural space was filled with yellowish, gelatinous
tissue. The pathological diagnosis was a small lymphocytic B-cell lymphoma, which was positive for L26 and Bcl-2
and negative for CD3 (Fig. 2). After surgery, the patient’s
right-hand apraxia was improved, but recurrent ischemic
attacks such as dysphasia and hemiparesis on the right side
occurred for 2 weeks. The initial neuroimaging results were
reviewed and another left retrobulbar enhancing mass was
found on CT and MR imaging, which was later confirmed
to be a small lymphocytic B-cell lymphoma using an ultrasonography-guided biopsy procedure. There was no evidence of bone marrow involvement in the NHL on a bone
scan. The patient underwent whole-brain radiation therapy at a dose of 3060 cGy and received booster radiation
therapy to the skull and left eye of 1980 cGy. After these
treatments, there was no evidence of tumor recurrence. The
patient currently has mild dysphasia and right-hand clumsiness 3 years after his initial diagnosis.
Discussion
Secondary NHLs often show bone involvement, but primary osseous lymphoma is rare, and accounts for only
3–4% of the patients with lymphoma.5 A true primary malignant lymphoma of the bone is defined as “a solitary mass
lesion with no evidence of disease at other sites and no systemic dissemination within 6 months of the detection of
tumor.”12 In particular, initial involvement of the calvaria is
extremely rare. Lymphomas of the cranial vault usually inJ. Neurosurg. / Volume 108 / May 2008

Non-Hodgkin lymphoma mimicking subacute subdural hematoma

FIG. 1. Preoperative axial unenhanced CT scans (A and B) and MR images (C–E) obtained in the patient. The CT scans
(A and B) show a compressive extraaxial lesion in the left frontoparietal area and a high density masslike lesion in the retrobulbar area that was overlooked. A T2-weighted MR image (C) shows a lesion with high signal intensity in the left frontoparietal area, whereas a T1-weighted image (D) shows a lesion with low signal intensity in the same area and altered
signal intensity in the left cranial vault. The lesion compresses the left hemisphere and left lateral ventricle. Another T1weighted image (E) shows the mass lesion in the left retrobulbar area.

volve the pericranium, underlying meninges, and subcutaneous tissues. These lesions are effectively treatable using
surgery and radiation therapy with a good outcome in most
cases.6,8
The signal intensity of a lymphoma on MR images is
nonspecific; most reported cases of skull lymphomas were
isointense on unenhanced MR images and showed marked
enhancement after administration of contrast medium.
Magnetic resonance imaging of lymphomas cannot be specific because its appearance can mimic those of metastatic
carcinoma, osteomyelitis, or meningioma.7 A high index of
clinical suspicion, awareness of the characteristic CT features, and aggressive therapy are therefore required for lymphomas, especially when a scalp mass extends through the
skull.9
Small lymphocytic lymphoma and chronic lymphocytic
leukemia are morphologically, phenotypically, and genotypically indistinguishable, differing only in the degree of
peripheral blood leukocytosis. Chronic lymphocytic leukemia is the most common type of leukemia in adults in the
Western world. Small lymphocytic lymphoma constitutes
only 4% of NHL cases. Chronic lymphocytic leukemia and
small lymphocytic lymphoma are much less common in
Asian countries. Most patients present at ages . 50 years
(median 60 years old); a male predominance has been
noted, with a male/female ratio of 2:1. The course and progJ. Neurosurg. / Volume 108 / May 2008

nosis of small lymphocytic lymphoma is variable and depends primarily on the clinical stage. Overall median survival is 4–6 years, but patients who present with minimal
tumor burden may survive for $ 10 years.2 The prognosis
of a patient with a skull lymphoma is uncertain, but either
direct cerebral invasion or leptomeningeal seeding should
indicate a less favorable prognosis.4,7,15 A primary lymphoma of bone is usually treated with local radiation therapy
and/or systemic chemotherapy, and the 5-year survival rate
has been reported to be . 60%.10,14 None of the previously
reported 16 patients survived longer than 24 months, however, indicating that patients with malignant lymphomas
originating from the cranial vault have an extremely poor
prognosis.13 Our case showed a good clinical outcome only
after surgery and radiotherapy.
Primary NHL of the cranial vault with periorbital metastasis is extremely rare; so far, only 1 other case has been
reported in the English literature.7,11 In our case, only neurological deterioration was observed, without a scalp lump
or exophthalmus symptoms. This lack of other symptoms
led to the misdiagnosis of the lymphoma as a subacute subdural hematoma.
Conclusions
The authors emphasize the rarity of primary cranial vault
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S. H. Yoon et al.

FIG. 2. Photomicrographs of a specimen from the tumor. The tumor was composed of small lymphocytic cells (A) involving the skull. The tumor cells are diffusely and robustly immunoreactive for L26 (B) and Bcl-2, compatible with a diagnosis of a small lymphocytic lymphoma (C). The Ki 67 labeling index was low (1%), indicating that few tumor cells
stained positive for Ki 67 (D). H & E, original magnification 3 100 (A and B) and 3 200 (C and D).

lymphoma and its importance in the differential diagnosis
of cranial vault mass lesions extending either intra- or extracranially.
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Manuscript submitted June 16, 2007.
Accepted August 20, 2007.
Address correspondence to: Sun Ha Paek, M.D., Ph.D., 28 Yeongeon-dong, Jongno-gue, Seoul 110-744, Korea. email: paeksh@snu.
ac.kr.

J. Neurosurg. / Volume 108 / May 2008