A 60-year-old man presents with acute confusion, aggressive behavior, and aphasia

T2-weighted FLAIR MRI A 60-year-old man presents with acute confusion, aggressive behavior, and aphasia. Imaging reveals a heterogeneously enhancing mass (5 x 2 x 2 cm) in the left medial temporal lobe with extensive peripheral edema (image above), but no significant contrast enhancement. A subtotal temporal lobectomy was performed on suspicion of a low-grade glioma.High-power view of biopsy from left temporal lobeThe diagnosis is herpes simplex encephalitis. PCR amplification of DNA from the specimen more specifically identified the causative agent as herpes simplex virus, type 1 (HSV1). The most common identifiable cause of viral encephalitis in hospitalized patients, HSV1 classically exhibits tropism for the orbitofrontal and temporal lobes bilaterally, but can on occasion present as a unifocal mass mimicking neoplasm as exemplified in this case. Untreated cases have a mortality rate of up to 70%, while in patients treated with a 14- to 21-day course of acyclovir the mortality rate is less than 10%. Although the patient in this case clinically improved while on a four-week course of acyclovir, he did not return to baseline functioning and was discharged to a nursing home.Primary infection with HSV1 is usually subclinical. Symptomatic primary infection may manifest as gingivostomatitis, pharyngitis, or a mononucleosis-like syndrome. During the initial infection, the virus undergoes retrograde transport along sensory axons and becomes established in latent form in senso...
Source: neuropathology blog - Category: Radiology Tags: infectious disease Source Type: blogs