Differential Diagnosis for Enlarged Breasts in a 65-year-old Man with Poorly Controlled Hypertension

• Single most likely diagnosis:
  • A. Spironolactone: This medication is known to cause gynecomastia (enlargement of breast tissue in men) as a side effect due to its anti-androgen activity. It blocks the effects of androgens (male hormones), leading to an imbalance that can cause breast tissue growth.
• Other Likely diagnoses:
  • None of the other options (B, C, D) are commonly associated with gynecomastia as a side effect. However, it's worth noting that while less likely, other medications and conditions could potentially contribute to hormonal imbalances leading to gynecomastia.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Although not directly related to the medications listed, it's crucial to consider other potential causes of gynecomastia that could be life-threatening if missed, such as testicular cancer, which can lead to hormonal imbalances. However, in the context of this question, focusing on medication side effects, testicular cancer or other hormone-secreting tumors would be critical to rule out.
• Rare diagnoses:
  • Other rare causes of gynecomastia, such as liver cirrhosis or hypogonadism, are not directly related to the medications listed but could be considered in a broader differential diagnosis, especially if other symptoms or signs are present. Medications like digitalis (for heart conditions) or ketoconazole (an antifungal) can also cause gynecomastia but are not listed among the options provided.