Differential Diagnosis for Excess Sweating in a 66-year-old Man

Single Most Likely Diagnosis

• Hyperhidrosis: This is a common condition characterized by excessive sweating, often affecting the palms, soles, and armpits. It can be primary (idiopathic) or secondary to other conditions. Given the age and presentation, primary hyperhidrosis or hyperhidrosis secondary to anxiety/stress is a plausible explanation.

Other Likely Diagnoses

• Anxiety or Stress: Excess sweating can be a symptom of anxiety disorders or stress reactions. The physical symptoms of anxiety, including sweating, can be pronounced in older adults.
• Hypothyroidism: Although less common, hypothyroidism can cause increased sweating among other symptoms like weight gain, fatigue, and cold intolerance.
• Medication Side Effects: Certain medications, such as antidepressants, can cause excessive sweating as a side effect.
• Menopause (in males, Andropause): While less commonly discussed, the hormonal changes associated with aging in men can lead to symptoms including hot flashes and sweating.

Do Not Miss Diagnoses

• Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodes of excessive sweating, hypertension, tachycardia, and palpitations. Although rare, missing this diagnosis could be fatal.
• Hyperthyroidism: Excessive sweating can be a symptom of an overactive thyroid gland. Untreated hyperthyroidism can lead to serious complications.
• Lymphoma: Some types of lymphoma can cause night sweats, which might be perceived as excess sweating.
• Tuberculosis: Night sweats are a classic symptom of TB, and while less common in presentation, it's a critical diagnosis not to miss.

Rare Diagnoses

• Carcinoid Syndrome: A rare condition caused by a carcinoid tumor that can produce excessive sweating among other symptoms like flushing and diarrhea.
• Autonomic Dysfunction: Disorders affecting the autonomic nervous system, such as multiple system atrophy, can lead to abnormal sweating patterns.
• Frey's Syndrome: A rare condition that can cause gustatory sweating (sweating in response to eating certain foods), usually as a result of nerve damage near the parotid gland.

Each of these diagnoses has a different set of implications for treatment and management, highlighting the importance of a thorough diagnostic workup for a patient presenting with excess sweating.