T. marneffei is an opportunistic pathogen common among HIV-infected patients. However, an increasing number of
T. marneffei infection in non-HIV-infected patients has recently been reported, especially in those with hematological malignancies, autoimmune diseases, organ transplantation, and diabetes mellitus [
1], but not in those with lung cancer. This is the first case report describing
T. marneffei infection in a non-HIV-infected patient with existing pulmonary LELC.
T. marneffei can invade multiple organs including the lung, skin, liver, bone, trachea and bronchus, and brain, like lung cancer. Patients may present respiratory symptoms including fever, cough, and expectoration involving the trachea and bronchus. The lesion in the chest imaging displays as single or multiple lobar consolidation, mass, cavity, interstitial exudation, pleural effusion, and pericardial effusion, commonly accompanied by hilum and mediastinal lymph node enlargement [
1]. Tracheoscopy shows tracheal and/or bronchial nodules or masses, thickened mucosa, and uneven, narrow lumen [
2,
3]. Indeed, the similarities in terms of clinical manifestations, chest imaging and bronchoscopy findings between talaromycosis marneffei and lung cancer are remarkable. The diagnosis of
T. marneffei infection mainly relies on tissue culture and pathological examination.
T. marneffei is thermally dimorphic, growing as a mycelium at 25 °C and as yeast-like cells at 37 °C on Sabouraud dextrose agar, exhibiting the production of soluble red pigment that diffuses into the medium. Furthermore,
T. marneffei yeast-like cells, which are 3–8 μm in diameter, could be observed by periodic acid-Schiff stain, revealing a transverse septum or sausage-shaped form that is the characteristic morphology [
4]. In this case, round to oval yeast-like cells with a transverse septum were observed in the left lung lesion. Ultimately, the patient was diagnosed with left primary pulmonary LELC complicated with talaromycosis marneffei. However, several manifestations primarily misled us toward lung cancer, ignoring
T. marneffei infection. Further, it was difficult to obtain evidence of the infection because of limited viable
T. marneffei in HIV-negative biopsy tissues and the low, positive rate of culture of
T. marneffei. Therefore, pathogens should be carefully searched for in pathological examination. Our patient presented fever and bronchial pathological evidence, and displayed chronic granulomatous inflammation. Some infections such as those of
Mycobacterium tuberculosis, non-
Mycobacterium tuberculosis,
Aspergillus, and
T. marneffei need to be considered and specific staining such as acid-fast stain, PAS, or others should be conducted for differential diagnosis.
Itraconazole, amphotericin B and voriconazole are effective in treating talaromycosis marneffei [
5,
6]. Pulmonary LELC is sensitive to paclitaxel- or docetaxel-based regimens [
7] and apatinib can be used as a third-line treatment for EGFR wild-type advanced non-small cell lung cancer [
8]. Our patient received voriconazole and subsequently docetaxel + carboplatin. During the first cycle of chemotherapy, exactly 20 days after beginning the treatment with voriconazole, the mass in the left lower lung was significantly reduced, which may be a result of the antifungal therapy. However, talaromycosis marneffei recurrence was caused by bone marrow suppression in the course of chemotherapy. Missed diagnosis of
T. marneffei in lung cancer can be fatal as the infection would spread owing to decreased white blood cell levels after chemotherapy. Thus, apatinib was approved for lung cancer with no white blood cell level reduction, which avoids inducing talaromycosis marneffei relapse.
In summary, diagnosis of lung cancer with easy access to pathological evidence is relatively simple, whereas diagnosis of talaromycosis marneffei is challenging. Missed diagnosis of talaromycosis marneffei may result in the fatal spread of the fungus during anti-tumor treatment. Therefore, the timely diagnosis and treatment of talaromycosis marneffei is critical, and attention should be paid by clinicians and pathologists.