The case of a patient with type B3 thymomacomorbid with Chlamydia psittaci (C. psittaci) pneumonia exhibiting rare features is presented in the current report. The patient was admitted at the Second Affiliated Hospital of Jiaxing University (Jiaxing, China) with a history of direct contact with poultry. Clinical manifestations included fever, shivers, cough, fatigue and poor appetite. Chest computed tomography (CT) indicated right lung pneumonia, while metagenomics next-generation sequencing using bronchoalveolar lavage fluid confirmed infection with C. psittaci. Additionally, positron emission tomography-CT suggested the presence of thymoma. After surgery and treatment with doxycycline and imipenem cilastatin, the patient was discharged showing signs of improvement. [ABSTRACT FROM AUTHOR]