Unusual Presentation of Pneumonic-Type Lung Adenocarcinoma and Diffuse Air-Space Consolidation

ABSTRACT

Introduction: Pneumonic-type lung adenocarcinoma (P-ADC) exhibits a pattern of lung cancer that is radiologically like pneumonia1. It may be misdiagnosed and represents a diagnostic challenge in the setting of progressive respiratory failure. We report a case of P-ADC which presented with rarely described extensive diffuse air-space consolidation. Case Presentation This is a 74-year-old female with a history of Crohn's disease on Mesalamine, Diabetes Mellitus, Hypertension, Hyperlipidemia and former smoker of 40 pack years admitted to the ICU for hypoxic respiratory failure requiring 100% O2 via HFNC. Twenty-two months prior to admission the patient underwent an EBUS following abnormal low dose lung cancer screening CT (Figure 1A-B). The CT demonstrated left infrahilar consolidation and multiple ground-glass nodules. The EBUS with biopsy/brushings of the mass in addition to bronchoalveolar lavage (BAL) were negative. She was lost to follow-up due to the COVID-19 pandemic. Two weeks prior to admission she was admitted for cough and dyspnea, treated for a community acquired pneumonia following CT showing excessive nodular opacities with left dense consolidations. On day of admission the patient presented from outpatient PFT with hypoxemia requiring 8LPM O2 and saturation of 90%, admitted to ICU on HFNC. Associated symptoms were recent unintentional 20 lbs weight loss and fatigue. CT imaging was remarkable for progressive, fulminant left lung consolidation and contralateral lung nodules (Figure 1C-D). The patient underwent a bedside bronchoscopy which showed normal anatomy and copious thin clear secretions. BAL samples showed malignant cells favouring nonsmall cell carcinoma. Further CT guided FNA showed the tumor cells were consistent with adenocarcinoma and positive for TTF1/Napsin A, negative for p40, and KRAS mutation detected. The patient was started on methylprednisolone, Carboplatin and Pemetrexad and discharged home on 6 LPM oxygen. The patient was shortly after re-admitted for a post obstructive pneumonia and progressive hypoxemic respiratory failure, she transitioned to hospice care and passed away during the hospitalization. Conclusion: P-ADC is uncommon and often misdiagnosed due to unusual presentation mimicking infectious and inflammatory diseases2. It is unclear whether P-ADC represents an extreme form, later stage, or entirely different entity of lung cancer and large airspace consolidations are rarely reported3. Lesions of pneumonia type that extend beyond one lobe on CT are associated with microscopy involvement of both lungs and pathologic correlation shows that CT is unable to reveal multifocality in a high percentage of cases which makes the extend of multifocal consolidations in this case rarely described4-6. (Figure Presented).