Herpes Simplex Virus Pneumonia in Patients with Hematologic Malignancies

Herpes simplex virus (HSV) pneumonia is rare and is usually seen in immunocompromised patients. Patients with hematologic malignancies and hematopoietic stem cell transplant (HSCT) are at risk. Most of the cases of HSV pneumonia are caused by HSV-1; however, cases caused by HSV-2 have also been reported. Mucocutaneous disease often precedes the development of pneumonia, with nonspecific symptoms that include fever, cough, and dyspnea. Worsening oxygenation and failure to wean off mechanical ventilation despite broad-spectrum antimicrobial coverage is also a common presentation. Diagnosis requires a high degree of suspicion and is based on isolation of the virus from respiratory secretions and demonstration of cytopathic effects on histopathology. Acyclovir is the most widely used drug for treatment and prophylaxis. With increasing evidence of resistance to acyclovir and its analogs, newer agents such as foscarnet and cidofovir are being recommended as treatment options. Prophylaxis in patients with seropositive HSV undergoing chemotherapy or in the immediate post-HSCT period has been shown to reduce HSV disease rates and mortality rates. This chapter will focus on incidence and transmission, pathogenesis, risk factors, clinical features, diagnosis, and management of HSV pneumonia in patients with hematologic malignancies and HSCT, as well as outcome and prognosis.