Adenovirus Type 11 Pneumonia Mimicking a Legionella Infection in a Patient with Bazex Syndrome and Occult Rectal Cancer.

Viral pneumonia rarely presents as a unilateral lobar pneumonia. We report the case of a 63-year-old man with severe right-sided lobar pneumonia resembling a Legionella infection, with high fever, dyspnea, hyponatremia, and elevated lactate dehydrogenase levels. Legionella testing was negative, and antibiotics were ineffective. However, multiplex polymerase chain reaction (PCR) revealed the presence of adenovirus, and bronchial wash fluid PCR confirmed adenovirus type 11. Subsequently, he developed skin symptoms consistent with Bazex syndrome and he was also diagnosed with occult rectal cancer. This case highlights that HAdV-11 pneumonia can mimic Legionella pneumonia and that paraneoplastic dermatoses may provide clues to underlying malignancies.