Introduction: Miliary dissemination of adenocarcinoma is a rare, aggressive, and often terminal form of metastasis characterized by countless tiny (millimetric) nodules spreading throughout the lungs, mimicking miliary tuberculosis. It affects less than 5% of all lung adenocarcinomas. The aim of this study is to present a case of miliary disseminated adenocarcinoma originating from the lung with all diagnostic requirements. Materials and Methods: A 57year old male patient with 80-pack year smoking status admitted for invasive diagnostics in our clinic between (22.10.2026-29.10.2026) due to x-ray showing miliary disseminated lung infiltrates and pleural effusion. Results: The light criteria of the pleural effusion showed exudate with high LDH values highly suspected of malignancy. Contrast enhanced CT was scheduled and it showed multiple miliary disseminated infiltrates, mediastinal and hilar lymphadenopathy. Liver and adrenal gland metastases were also noted. Bronchoscopy with TBB from the branch of the right upper lobe, together with TBNA from position 7 and 11R, both came positive for adenocarcinoma. Immunohistochemistry was positive in 50% of ROS1; TTF1; CK7; CEA; and negative on CK20; EGFR, ALK, PDL1 confirming primary adenocarcinoma of the lung. Additionally, the patient was presented on tumor bord for treatment options and staging being T4N3M1c2. Conclusion: Miliary disseminated adenocarcinoma is aggressive and usually diagnosed late. Immunohistochemistry can provide an exact origin of the malignant disease.