Differential Diagnosis for Bilateral Foot Discomfort

The patient presents with bilateral foot discomfort, swelling, and tenderness, along with a history of hypertension, hyperlipidemia, and recent significant weight loss. Laboratory results show elevated Rheumatoid Factor (RF) and Anti-CCP Ab, IgG/IgA. Here is a categorized differential diagnosis:

• Single Most Likely Diagnosis
  • Rheumatoid Arthritis (RA): The patient's symptoms of bilateral foot discomfort, swelling, and tenderness, particularly worse in the morning and improving with movement, are classic for RA. Elevated RF and Anti-CCP Ab support this diagnosis, as these are common in RA. The patient's recent weight loss and improvement in blood pressure could be unrelated or secondary to increased mobility and exercise.
• Other Likely Diagnoses
  • Gout: Given the patient's history of hyperlipidemia and recent significant weight loss, gout is a consideration, especially with the description of discomfort feeling like "walking on marbles" and localized pain. However, the absence of acute, severe monoarticular attacks and the lack of uric acid level information make this less likely.
  • Plantar Fasciitis: The heel pain, especially on the left foot, could suggest plantar fasciitis, a common condition often related to poorly fitting shoes or increased physical activity. The improvement with movement is not typical for plantar fasciitis, which usually worsens with activity.
  • Morton's Neuroma: The tingling and numbness in the second digit of the right foot could indicate Morton's neuroma, a condition that causes compression of the nerves between the toes. This diagnosis would not explain the systemic symptoms or laboratory findings.
• Do Not Miss Diagnoses
  • Peripheral Artery Disease (PAD): Although less likely given the patient's age and recent improvement in cardiovascular risk factors, PAD could cause leg and foot pain, especially with exertion. The absence of claudication symptoms makes this less probable.
  • Diabetic Neuropathy: Despite no mentioned history of diabetes, the patient's history of hyperlipidemia and significant weight loss could be related to undiagnosed diabetes. Diabetic neuropathy could explain the tingling and numbness but would not account for the inflammatory markers.
• Rare Diagnoses
  • Psoriatic Arthritis: This condition could present with foot pain, swelling, and skin changes, but the absence of psoriatic skin lesions or nail changes makes this less likely.
  • Lyme Disease: Given the patient's symptoms and elevated inflammatory markers, Lyme disease could be considered, especially if the patient has been exposed to ticks. However, the lack of systemic symptoms such as fever, headache, or a characteristic rash makes this diagnosis less probable.
  • Sarcoidosis: This multisystem disease can cause arthritis and foot pain but would typically be accompanied by other systemic symptoms such as lung involvement or skin lesions, which are not mentioned in the patient's history.