A 15-year-old girl is evaluated for recurrent episodes of focal onset seizures evolving to bilateral tonic-clonic seizures over the past several months. She has also had headaches that are severe enough to keep her home from school. The patient has no prior medical conditions. MRI of the brain is shown in the exhibit.

Which of the following histopathological findings are most likely present in the abnormal lesion?

Question

A 15-year-old girl is evaluated for recurrent episodes of focal onset seizures evolving to bilateral tonic-clonic seizures over the past several months. She has also had headaches that are severe enough to keep her home from school. The patient has no prior medical conditions. MRI of the brain is shown in the exhibit.

Which of the following histopathological findings are most likely present in the abnormal lesion?

Quizplus · Accepted Answer

11ec160b_3596_a864_9249_1b0e9b8dbbb8_MD0001_00 This patient with recurrent headaches and seizures has multiple flow voids in the left temporoparietal lobe demonstrated by MRI, consistent with a cerebral arteriovenous malformation (AVM). AVMs are vascular malformations in which blood courses directly from arteries to veins, without passing through an intervening capillary bed. These tangled vessels with turbulent flow can lead to aneurysm development, bleeding, and damage to the surrounding brain. Microscopy of AVMs shows abnormal vessels, including irregular arteries and large veins with thickened walls, and gliotic brain tissue. AVMs frequently present in children and young adults with headaches and seizures as well as intracranial hemorrhage (eg, intraparenchymal, subarachnoid hemorrhage). Some patients are initially asymptomatic and diagnosed incidentally by imaging. A nest of abnormal vessels with "bag of worms" appearance may be seen on angiography. MRI may reveal prior hemorrhage and multiple dark flow voids, indicative of swift blood flow. (Choice A) Dense perivascular aggregates of atypical lymphoid cells are a histologic feature of primary CNS lymphoma, which is typically a diffuse large B-cell lymphoma. Although clinical symptoms may include seizures, it usually presents in older adults or immunocompromised patients. MRI would likely reveal an enhancing mass. (Choice B) Lipid-laden macrophages with phagocytized myelin debris are seen in the demyelinating plaques of multiple sclerosis. Symptoms are variable but commonly include unilateral visual disturbance (eg, optic neuritis) and focal sensory and motor deficits. MRI typically reveals periventricular white matter lesions. (Choice C) Histologic findings in cerebral Toxoplasma gondii infection include necrotic debris with surrounding inflammation, tachyzoites, and pseudocysts of bradyzoites. Although seizures and headaches are a frequent manifestation, CNS toxoplasmosis usually occurs in immunocompromised patients. Imaging would likely reveal ring-enhancing lesions. (Choice D) Necrosis surrounded by malignant cells (pseudopalisading necrosis) and microvascular proliferation are features of glioblastoma, a high-grade infiltrating astrocytoma. It commonly presents with seizures, headache, and neurologic deficits in middle-aged or older adults (rather than children). MRI would likely reveal a mass with central hemorrhagic necrosis, vasogenic edema, and possible extension to the contralateral hemisphere. Educational objective: Cerebral arteriovenous malformations (AVMs) are vascular malformations histologically characterized by a tangle of abnormal vessels, including large veins with thickened walls and irregular arteries. AVMs may present with intracranial hemorrhage, headache, and/or seizures. Radiologic findings include abnormal vasculature with a "bag of worms" appearance and multiple dark flow voids.

A 15-Year-Old Girl Is Evaluated for Recurrent Episodes of Focal