Differential Diagnosis for Patchy Erythematous Eczematous Lesions

Given the description of patchy, erythematous, eczematous lesions bilaterally on both lower limbs of an elderly diabetic and hypertensive female patient, with a special appearance of pustules at hair follicles and partial improvement with augmentin and mupirocin, the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Folliculitis: The presence of pustules at hair follicles is highly suggestive of folliculitis, which can be caused by bacterial (most commonly Staphylococcus aureus), fungal, or viral infections. The patient's partial response to antibiotics (augmentin and mupirocin) supports this diagnosis, as these are commonly used to treat bacterial folliculitis.

• Other Likely Diagnoses

  • Eczema (Atopic Dermatitis or Contact Dermatitis): The description of patchy, erythematous, eczematous lesions could fit with various forms of eczema. However, the specific mention of pustules at hair follicles leans more towards folliculitis, but eczema cannot be ruled out without further investigation.
  • Stasis Dermatitis: Given the patient's age and hypertension, stasis dermatitis is a possibility, especially if there's evidence of venous insufficiency. However, the follicular involvement is less typical for stasis dermatitis.
  • Diabetic Dermopathy: This condition is common in diabetic patients and presents as brown, circular, or oval patches, typically on the legs. While it doesn't typically present with pustules, the patient's diabetes status makes it a consideration.

• Do Not Miss Diagnoses

  • Cellulitis: Although the patient showed partial improvement with antibiotics, cellulitis is a serious condition that requires prompt treatment. It can present with erythema, swelling, and warmth of the skin, and while pustules are not a hallmark, the presence of any skin infection in a diabetic patient warrants consideration of cellulitis due to its potential for serious complications.
  • Necrobiosis Lipoidica: A condition associated with diabetes, characterized by necrotic lesions in the skin. While it doesn't typically present with pustules, its association with diabetes and potential for ulceration makes it a "do not miss" diagnosis.

• Rare Diagnoses

  • Erythema Nodosum: An inflammatory condition characterized by tender red nodules, typically on the shins. It can be associated with various conditions, including infections and systemic diseases. The presence of pustules is not typical, but the condition's rarity and potential for systemic associations make it a consideration in a differential diagnosis.
  • Pseudomonas Folliculitis (Hot Tub Folliculitis): Although less likely given the description and the patient's response to treatment, this condition can occur after exposure to contaminated water and presents with follicular pustules. It's rare and typically associated with a history of recent hot tub use or swimming in contaminated water.