Rare misdiagnosed case of penicilliosis marneffei in an immunocompetent patient

Background Penicilliosis marneffei is a rare disease caused by Talaromyces marneffei, which is endemic in Southeast Asian countries, and usually occurs in immunocompromised or immunodeficient hosts. We report an unusual misdiagnosed case of penicilliosis marneffei in an immunocompetent patient from a non-endemic area of China. Case presentation: A 59-year-old man presented to hospital with a cough and progressive hemoptysis for a 3-month period. Clinical characteristics, radiological abnormalities, and prognosis were analyzed. Detailed examinations, chest computed tomography, and bronchoscopy were performed. The patient was misdiagnosed as having lung cancer and provided anti-tumor treatment for 1 month in the early stage. Imaging and bronchoscopy showed a neoplasm in the basal segment in the left lung, but a tissue biopsy did not establish a diagnosis. He subsequently underwent lobectomy for the lesion. The final pathological diagnosis was penicilliosis marneffei based on immunohistochemical staining. He was then prescribed specific anti-fungal treatment of voriconazole 200 mg twice daily for 12 weeks. Conclusion Timely fungal culture and pathological examination of clinical specimens are critical for the diagnosis of penicilliosis marneffei, especially in non-endemic regions and immunocompetent patients.