Inflammatory pseudotumor associated with HSV infection of rectal vascular endothelium in a patient with HIV: a case report and literature review

BACKGROUND: Herpes simplex virus (HSV) typically infects oral or anogenital squamous epithelium and causes blisters and ulcerations. Here we reported an unusual case of HSV induced exuberant rectal inflammatory pseudotumor with vascular endothelial involvement. CASE PRESENTATIONS: A 52-year old man with HIV presented with abdominal pain, rectal drainage and constipation. Proctoscopy and CT scans revealed an 8 × 5 × 4 cm circumferential, mid-lower rectal mass that was concerning for malignancy. PET-CT showed mild to moderate FDG uptake of the rectal mass. Repeated biopsies showed exuberant lymphoplasmacytic inflammation with rich eosinophils and necrosis in the submucosa and scattered single or multi-nucleated viral inclusions in vascular endothelial cells that were positive for HSV by immunostains. There was no evidence of malignancy on histology or by immunostains. The patient started valacyclovir for three weeks and symptoms resolved after the antiviral therapy. Follow-up CT and sigmoidoscopy with biopsy revealed no rectal mass or drainable collection. CONCLUSIONS: HSV may present as proctitis with exuberant inflammatory response and mass-like lesion, and damages vascular endothelial cells in patients with HIV. The HSV-associated mass-like lesion can be effectively treated by 3-week valacyclovir.