Presentation
Expressive dysphasia for 7 days.
Patient Data
A solitary intracerebral lesion in the inferior left frontal lobe with associated mass effect, edema and subtle hyperdense rim.
T2 hyperintense mass centered in the white matter of the left frontal lobe. There is associated peripheral diffusion restriction and a small focus of peripheral enhancement (demonstrated on the post-contrast images).
7 mm hypoechoic region in the left testis.
Left para-aortic lymph node, averaging 3.1 cm.
The working diagnosis initially included a primary brain tumor and lymphoma.
The abdominal CT demonstrated a 32 mm para-aortic lymph node. Testicular ultrasonography revealed a 7 mm hypoechoic region in the left testicle.
Stereotactic biopsy of the para-aortic lymph node revealed a histological diagnosis of metastatic seminoma.
The axial T2 images demonstrated a hyperintense white matter lesion in the left frontal lobe. Diffusion imaging revealed a peripheral rim of diffusion restriction consistent with a possible diagnosis of active demyelination. T1 post-gadolinium images showed a small focus of enhancement at the periphery of the lesion.
The patient had curative chemotherapy for his metastatic seminoma. He subsequently had a resection of his left frontal lobe lesion.
Histology from the resected lesion confirmed demyelination and reactive changes with no evidence of neoplasia.
The patient subsequently underwent a left inguinal orchiectomy. The histology revealed a scar typical of a regressed tumor.
Case Discussion
This case demonstrates tumefactive demyelination as a paraneoplastic disorder. It is a rare, locally aggressive form of demyelination 1. In patients without a diagnosis of multiple sclerosis it can pose a diagnostic quandary and can often mimic a neoplasm. Peripheral diffusion restriction, a predilection for the periventricular and deep white matter, minimal mass effect and decreased perfusion leans the diagnosis towards tumefactive demyelination rather than malignancy 2.
Paraneoplastic neurological disorders are remote manifestations of malignancy unrelated to metastases or the tumor itself. The greatest chance of neurological recovery comes from treating the associated malignancy and hence early diagnosis plays a vital role 3.
Case contributed by Dr David Swienton and Dr Aanand Vibhakar
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