Tumefactive demyelinating lesion: experience with two unusual patients.

Tumefactive demyelinating lesion, a variant of multiple sclerosis, is a solitary large demyelinating lesion, which mimics cerebral neoplasm. Distinguishing tumefactive lesions from other etiologies of intracranial space-occupying lesions is essential to avoid inadvertent surgical or toxic chemotherapeutic interventions. We report two unusual cases of tumefactive demyelinating lesion. The first patient presented with recurrent right focal tonic-clonic seizures with secondary generalization of three-month duration. Her neurological examination was normal. Another patient presented with right homonymous hemianopia. In this patient, the diagnosis was established after biopsy of the lesion, which revealed perivascular lymphocytic infiltrate and aggregates of foam cells in white matter with relatively uninvolved grey matter, suggestive of tumefactive demyelinating lesion. Administration of intravenous methylprednisolone resulted in rapid clinical improvement in both the patients and the brain lesion decreased in size. Both, epilepsy and homonymous hemianopia, are unusual manifestations of tumefactive demyelinating lesions. In our cases, cerebral tumors were initial diagnoses. Presence of an open ring or incomplete ring lesions and other magnetic resonance characteristics helped in differentiating demyelinating lesions from other neoplastic and infective diseases of the brain. Differential diagnosis of tumefactive demyelinating lesions, at times, may prove to be a challenging task for the treating physician.