B80-5-45 Miliary-Pattern Pulmonary Metastases From Suspected Gynecologic Primary Presenting as Progressive Hypoxemic Respiratory Failure

Abstract Introduction Diffuse micronodular or miliary lung disease is commonly associated with tuberculosis, fungal infections, or sarcoidosis. Miliary-pattern pulmonary metastases are far less frequent and can mimic infectious etiologies, often delaying diagnosis. We present a case of rapidly progressive hypoxemic respiratory failure due to diffuse pulmonary metastases from a suspected uterine/cervical malignancy. Case Presentation A previously healthy 48-year-old woman presented with two weeks of worsening shortness of breath, fatigue, and hypoxia requiring 2-3 L/min of supplemental oxygen. Initial laboratory evaluation revealed acute kidney injury with hypercalcemia, hypokalemia, and urinary tract infection. Vital signs were stable aside from hypoxia. CT chest/abdomen/pelvis demonstrated innumerable small pulmonary nodules with scattered patchy airspace opacities, mildly enlarged mediastinal lymph nodes, and bilateral iliac chain lymphadenopathy. The radiographic pattern raised concern for miliary tuberculosis, fungal pneumonia, pneumoconiosis, or less likely miliary metastases. She was started on ceftriaxone, azithromycin, IV fluids, calcitonin, and electrolyte replacement. HIV, hepatitis serologies, Quantiferon, and AFB studies were negative. Despite treatment, her oxygen requirement escalated to 6-10 L/min. Bronchoscopy was deferred due to worsening hypoxemia. She underwent CT-guided biopsy of a left lung nodule, which revealed metastatic non-small cell carcinoma with neuroendocrine features. Hematology/oncology evaluation prompted repeat CT abdomen/pelvis with contrast, which showed an ill-defined 5.5 × 6.7 × 9.4 cm mass involving the uterus and uterine cervix with extension toward the urinary bladder, highly suspicious for gynecologic malignancy. Additional liver lesions and bony abnormalities were noted, consistent with disseminated disease. She completed a 7-day course of antibiotics for presumed community-acquired pneumonia without improvement in hypoxia. She remained steroid-dependent with persistent oxygen needs and was transferred to a higher level of care for gynecologic oncology evaluation and management of advanced malignancy-associated respiratory failure. Discussion This case demonstrates a rare presentation of miliary-pattern pulmonary metastases from a suspected gynecologic primary, initially indistinguishable from infectious or inflammatory lung disease. Gynecologic malignancies rarely present with diffuse pulmonary metastases; when they do, they can closely mimic atypical infections and delay recognition of the true etiology. Miliary-pattern pulmonary metastases should be considered in patients with diffuse micronodular lung disease who fail to improve with empiric antimicrobial therapy or exhibit signs of disseminated malignancy. This case underscores the importance of maintaining a broad differential when evaluating miliary lung disease and recognizing malignancy as a potential cause of hypoxemic respiratory failure. This abstract is funded by: None