Differential Diagnosis
- Single most likely diagnosis
- B. Necrobiosis lipoidica diabeticorum (NLD): This condition is strongly associated with diabetes mellitus (DM) and presents as tender, well-demarcated red lesions, often on the shins. The patient's history of DM and the description of the lesion make NLD a highly plausible diagnosis.
- Other Likely diagnoses
- C. Cellulitis: Given the patient's presentation with a tender, red lesion on the shin, cellulitis is a possible diagnosis. Cellulitis is an infection of the skin and subcutaneous tissues and can occur in anyone, but the presence of DM might increase the risk due to potential neuropathy and vascular complications.
- A. Erysipelas: This is a type of skin infection that involves the upper dermis, typically caused by beta-hemolytic group A Streptococcus. It presents as a well-demarcated, red, and tender lesion, which could fit the patient's symptoms. However, it's less directly associated with DM compared to NLD.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Deep Vein Thrombosis (DVT): Although not listed among the options, DVT is a critical condition to consider in a patient with Afib on amiodarone presenting with leg symptoms. The risk of DVT is increased in patients with Afib due to the potential for clot formation.
- Septic Arthritis or Osteomyelitis: Infections that could present with localized redness and tenderness, especially in a diabetic patient who might have compromised sensation or circulation.
- Rare diagnoses
- D. Side effects of amiodarone: While amiodarone can cause a variety of skin reactions, the specific presentation of a tender, well-demarcated red lesion on the shin is less commonly associated with amiodarone compared to other diagnoses listed. However, it remains a possibility, especially given the patient's use of this medication.