BackgroundMycobacterium xenopi-infected patients have a high prevalence of pulmonary cavities and nodules. However, the clinical course for patients with miliary nodules due to M. xenopi has not yet been reported.Case presentationWe encountered a case of miliary nodules with gradually worsening coughing and sputum production in a 44-year-old male who had renal dysfunction due to glomerulosclerosis with a decade-long history of steroid therapy. Although we started anti-tuberculosis treatment on clinical suspicion of miliary tuberculosis, cultures of sputum and bronchial lavage were both positive for M. xenopi. The patient was successfully treated with rifampin, ethambutol and clarithromycin, without fibrosis. It was unclear whether the miliary pattern was induced by hematogenous or endobronchial spread of the M. xenopi infection.ConclusionEven when clinical and radiological disease manifestations are similar to those of miliary tuberculosis, M. xenopi infection should be considered in the differential diagnosis of miliary nodules.

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DESCRIPTIONA 43-year-old man with a 9-year history of schizophrenia presented with productive cough, and was diagnosed with pneumonia of the left lung. As treatment with clarithromycin followed by garenoxacin was not effective, the patient was referred to our hospital. Although physical examination was unremarkable, chest X-ray and enhanced CT showed an irregular-shaped mass in the left inferior lobe, with airway stenosis of the lobar bronchus due to wall thickness and hilar lymphadenopathy (figure 1A-C). The bronchoscopic view of swollen mucosa with nodules was compatible with lung cancer mucosal invasion ( figure 2A, B). However, mucosal biopsies revealed tiny clumps including filamentous branching of the bacteria with radial arrangement surrounded by inflammatory cells ( figure 2C) and food residues. These pathological findings were compatible with endobronchial actinomycosis. The patient was treated with parenteral ampicillin (6 g/day) for 1 month, followed by oral amoxicillin (1.5 g/day) for 5 months. After the antibiotic treatment, chest CT showed disappearance of the mass shadow, airway stenosis and hilar lymphadenopathy.The patient had many risk factors for pulmonary actinomycosis, such as pre-existing dental disease, poor oropharyngeal hygiene and smoking.