Differential Diagnosis for Red Nodular Bumps near Ankles
Single Most Likely Diagnosis
- Erythema nodosum: This condition is characterized by the sudden onset of tender, red nodules on the skin, typically on the lower extremities, especially near the ankles. It is often associated with an underlying infection, inflammatory condition, or medication use. The description provided matches closely with erythema nodosum, making it the most likely diagnosis.
Other Likely Diagnoses
- Cellulitis: Although the question specifies that the condition is not vascular, cellulitis can sometimes present with nodular lesions and is a common cause of red, painful skin lesions on the lower extremities. It's essential to consider this diagnosis, especially if there's a history of trauma or infection.
- Folliculitis: This is an inflammatory condition affecting the hair follicles, which can cause red, painful bumps. While it's more common in areas with dense hair follicles, it could be considered in the differential for red nodular bumps near the ankles, especially if the patient has recently shaved or has an underlying skin condition.
- Contact dermatitis: This condition occurs when the skin comes into contact with an irritant or allergen, leading to a red, itchy, and sometimes bumpy rash. If the patient has been exposed to a new substance or product, contact dermatitis could be a possible diagnosis.
Do Not Miss Diagnoses
- Deep vein thrombosis (DVT): Although the question specifies that the condition is not vascular, it's crucial to consider DVT in the differential diagnosis due to its potential severity and the fact that early symptoms can sometimes be non-specific. DVT can cause redness, swelling, and pain in the affected limb, which might be mistaken for a skin condition.
- Osteomyelitis: This is an infection of the bone, which can cause pain, redness, and swelling over the affected bone. While less common, osteomyelitis near the ankle could potentially cause symptoms similar to those described, making it a critical diagnosis not to miss.
Rare Diagnoses
- Necrobiosis lipoidica: This is a rare skin condition characterized by necrotic, granulomatous lesions, often on the lower extremities. It can cause red, painful nodules and is associated with diabetes in some cases.
- Granuloma annulare: This condition presents with ring-shaped lesions composed of small, firm bumps, typically on the hands and feet. While it's not typically painful, some variants can cause discomfort, and it's a rare condition to consider in the differential diagnosis.
- Sarcoidosis: A systemic disease that can cause granulomatous lesions in various parts of the body, including the skin. Skin manifestations can include red, painful nodules, although this is less common.