Differential Diagnosis for Abscess to Left Anterolateral Thigh

Single Most Likely Diagnosis

• Cutaneous Abscess: This is the most common cause of a localized collection of pus in the skin and soft tissues, often resulting from bacterial infection, typically Staphylococcus aureus. The anterolateral thigh is a common site due to its exposure to trauma and bacterial colonization.

Other Likely Diagnoses

• Furuncle or Carbuncle: These are infections of the hair follicle (furuncle) or a group of hair follicles (carbuncle), usually caused by Staphylococcus aureus. They can present similarly to an abscess but are typically centered around a hair follicle.
• Cellulitis: An infection of the skin and subcutaneous tissues, which can present with redness, swelling, and warmth but does not typically form a localized abscess. It's a consideration if the borders of the affected area are not well-defined.
• Pyomyositis: An infection of the skeletal muscle, which can present as a localized abscess within the muscle. It's less common but should be considered, especially if there's significant muscle involvement.

Do Not Miss Diagnoses

• Necrotizing Fasciitis: A severe infection of the fascia, which can rapidly progress and is life-threatening. It presents with severe pain out of proportion to the physical findings, and the skin may appear normal or show signs of necrosis.
• Gas Gangrene: Caused by Clostridium perfringens, this condition is characterized by infection of the muscle with gas production. It's a medical emergency due to its rapid progression and high mortality rate.
• Deep Vein Thrombosis (DVT): While not an infection, DVT can present with swelling and warmth of the leg and is a critical diagnosis to consider due to its risk of pulmonary embolism.

Rare Diagnoses

• Mycobacterial Infection: Infections such as those caused by Mycobacterium tuberculosis or atypical mycobacteria can cause abscesses or chronic infections of the skin and soft tissues, especially in immunocompromised individuals.
• Actinomycosis: A chronic bacterial infection that can cause abscesses, usually in the face and neck but can occur in other parts of the body, including the thigh.
• Echinococcosis: A parasitic infection caused by Echinococcus species, which can form cysts in various parts of the body, including the soft tissues of the thigh, though this is exceedingly rare.