Differential Diagnosis
- Single most likely diagnosis
- Malignant pleural effusion: The patient has a history of breast cancer with metastasis to the liver and bones, and the presence of a large bilateral pleural effusion with a high lactate dehydrogenase level in the pleural fluid is consistent with a malignant effusion. The straw-colored fluid and negative cytology do not rule out malignancy, as cytology may be negative in up to 20% of cases.
- Other Likely diagnoses
- Hepatic hydrothorax: The patient has liver metastasis, which can cause hepatic hydrothorax, a transudative pleural effusion. However, the high lactate dehydrogenase level in the pleural fluid and the presence of a large effusion make this diagnosis less likely.
- Cardiac effusion: Although the patient has a history of anthracycline use, which can cause cardiotoxicity, the normal cardiac examination and lack of jugular venous distention make this diagnosis less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Pulmonary embolism: The patient has a history of cancer, which increases the risk of pulmonary embolism. Although the patient does not have typical symptoms such as fevers or night sweats, pulmonary embolism can present with nonspecific symptoms, and a high index of suspicion is necessary.
- Pneumonia: The patient has a nonproductive cough and pleuritic chest pain, which could be consistent with pneumonia. Although the Gram stain is negative, pneumonia should be considered, especially in a patient with a compromised immune system.
- Rare diagnoses
- Chylothorax: The patient has a history of cancer, which can cause chylothorax, a rare type of pleural effusion. However, the straw-colored fluid does not suggest chyle, making this diagnosis unlikely.
- Amyloidosis: The patient has a history of cancer, which can be associated with amyloidosis, a rare condition that can cause pleural effusions. However, the lack of other symptoms such as weight loss, fatigue, or macroglossia makes this diagnosis unlikely.