A 66-year-old woman is evaluated for a 6-week history of increasing dyspnea. She has also has right-sided pleuritic chest pain when lying down and an occasional cough. She has lost 9.1 kg (20.0 lb) in the last 3 months. She has no other medical problems and takes no medications.
On physical examination, temperature is 36.4 °C (97.5 °F), blood pressure is 119/63 mm Hg, pulse rate is 77/min, and respiration rate is 20/min; oxygen saturation is 92% breathing ambient air. BMI is 21. There is no jugular venous distention. Heart sounds are normal with no murmurs. Pulmonary examination reveals dullness to percussion and decreased breath sounds over both lower lung zones. A 4-cm right breast mass is palpated.
Chest radiograph demonstrates bilateral pleural effusions but no evidence of infiltrate or pulmonary vascular congestion.
Thoracentesis is performed, and 500 mL of serosanguineous fluid is removed.
Serum lactate dehydrogenase | 124 U/L |
Serum total protein | 6.2 g/dL (62 g/L) |
Pleural fluid lactate dehydrogenase | 320 U/L |
Pleural fluid total protein | 4 g/dL (40 g/L) |
Pleural fluid glucose | 55 mg/dL (3.1 mmol/L) |
Pleural fluid total nucleated cells | 3500/µL (3.5 × 109/L) (15% lymphocytes) |
Pleural fluid Gram stain is negative. Cytology is negative for malignancy.
In addition to evaluation of the breast mass, which of the following is the most appropriate management?