CRA94 FLUOROSCOPIC GUIDED TRANSBRONCHIAL LUNG BIOPSY UNMASKS METASTATIC ADENOCARCINOMA MIMICKING NONRESOLVING PNEUMONIA

Nor Safiqah Sharil1,2, Boon Hau Ng1, Nurul Aisyah Abdul Rahman1, Aminath Naqsha1, Anis Ayishah Mohd Dali1, Rose Azzlinda Osman1, Hsueh Jing Low3, Nik Nuratiqah Nik Abeed1, Andrea Yu-Lin Ban1

1. Respiratory Unit, Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Hospital Canselor Tuanku Muhriz, Kuala Lumpur, Malaysia.
2. Internal Medical Unit, Faculty of Medicine and Health Science, Universiti Sains Islam Malaysia, Nilai, Negeri Sembilan.
3. Department of Anesthesiology and Critical Care, Faculty of Medicine, Universiti Kebangsaan Malaysia, Hospital Canselor Tuanku Muhriz, Kuala Lumpur, Malaysia.

Introduction
Failure of radiological consolidation to resolve after adequate antimicrobial therapy warrants a search for pneumonia mimickers. Lung adenocarcinoma, particularly with lepidic or lymphangitic spread, may masquerade as infection or miliary tuberculosis. Timely tissue diagnosis is crucial, and clinicians should maintain a high index of suspicion and proceed with biopsy when clinical and radiological features are atypical or non-resolving.

Case Report
A 73-year-old Malay man, an ex-smoker, 10 pack-years, presented with a one-month productive cough and progressive exertional dyspnoea despite four weeks of oral cefuroxime for sputum cultureproven Klebsiella pneumoniae pneumonia treated at a different centre. Serial sputum AFB smears were negative. Chest radiographs showed an unchanged lobulated right upper-zone opacity with bilateral reticulonodular infiltrates. CECT thorax reported consolidative changes involving the right upper lobe with diffuse multiple tiny lung nodules, minimal right pleural effusion, and multiple lytic sclerotic bone lesions suspicious of metastasis. Flexible bronchoscopy was macroscopically normal; however, fluoroscopy-guided trans-bronchial lung biopsies from the right lower lobe were performed. Histopathology revealed cords and nests of neoplastic cells within a desmoplastic stroma, positive for TTF-1, Napsin-A, and CK7, confirming metastatic pulmonary adenocarcinoma. Staging established stage IVB disease with nodal and skeletal involvement. While awaiting molecular profiling, the patient received dexamethasone for lymphangitis carcinomatosis and was referred to oncology.

Discussion
Lung adenocarcinoma can present as non-resolving bacterial pneumonia or miliary TB, especially when superimposed infection co-exists. This case underscores three key points: (1) persistent consolidation after appropriate antibiotics demands re-evaluation; (2) diffuse infiltrates with sclerotic bone lesions should raise suspicion of metastatic malignancy; and (3) fluoroscopic-guided trans-bronchial lung biopsy remains a simple, low-cost, high-yield technique when bronchoscopic visual cues are absent and advanced navigation tools are unavailable. Early biopsy-driven diagnosis accelerates molecular testing, avoids therapeutic delay, and streamlines palliative oncology care.