Differential Diagnosis for 79-year-old Female with Nonproductive Cough and Malaise

Single Most Likely Diagnosis

• Hypertensive Crisis: The patient's significantly elevated blood pressure (BP 200/100) in the context of her history of hypertension and current symptoms of nonproductive cough and malaise could indicate a hypertensive crisis. The cough could be related to heart failure or pulmonary edema, which are complications of uncontrolled hypertension.

Other Likely Diagnoses

• Heart Failure: Given the patient's history of hypertension and the presentation of nonproductive cough and malaise, heart failure should be considered. The cough could be indicative of pulmonary congestion.
• Pneumonia: Although the patient was tested negative for Covid and flu a month ago, pneumonia remains a possibility, especially if the cough has persisted. The absence of fever does not rule out pneumonia, particularly in elderly patients who may not always present with typical symptoms.
• Chronic Kidney Disease (CKD) Exacerbation: With a history of having one kidney, any increase in blood pressure could potentially worsen renal function, leading to symptoms like malaise.

Do Not Miss Diagnoses

• Pulmonary Embolism (PE): Although less likely, PE is a critical diagnosis that cannot be missed due to its high mortality rate. The nonproductive cough and malaise could be symptoms of a PE, especially in an elderly patient.
• Aortic Dissection: This is a life-threatening condition that can present with hypertension and nonspecific symptoms like malaise. The absence of typical chest pain does not rule out this diagnosis.
• Infectious Causes (e.g., Tuberculosis): Despite negative tests for common infections, other less common infectious causes like tuberculosis should be considered, especially if the patient has been exposed or has risk factors.

Rare Diagnoses

• Lymphangitic Carcinomatosis: A rare condition where metastatic cancer spreads to the lymphatics of the lung, causing a nonproductive cough among other symptoms.
• Sarcoidosis: An autoimmune disease that can cause a nonproductive cough and malaise, among other systemic symptoms.
• Eosinophilic Pneumonia: A rare condition characterized by an accumulation of eosinophils in the lungs, which can cause cough and systemic symptoms.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, and further diagnostic testing to determine the underlying cause of her symptoms.