Differential Diagnosis for Redness to the Right Hallux Region with Warmth and Slight Tenderness

Single Most Likely Diagnosis

• Cellulitis: This is a common bacterial skin infection that can cause redness, warmth, and tenderness, especially in the lower extremities. The hallux (big toe) region is a typical location due to its susceptibility to trauma and bacterial entry points.

Other Likely Diagnoses

• Paronychia: An infection of the skin around the nail, which can cause redness, swelling, and tenderness. It's a common condition, especially if there's a history of nail biting, picking, or recent nail trauma.
• Ingrown Toenail: This condition occurs when the nail grows into the surrounding skin, causing irritation, redness, warmth, and tenderness. It's a frequent issue, particularly in the hallux due to pressure from poorly fitting shoes or abnormal nail growth.
• Gout: Although more commonly associated with intense pain, gout can also present with redness and warmth over the affected joint, which could be the metatarsophalangeal joint of the big toe.

Do Not Miss Diagnoses

• Osteomyelitis: A bone infection that can present with localized redness, warmth, and tenderness. It's crucial to consider, especially in patients with a history of trauma, diabetes, or compromised immune systems, as it requires prompt treatment to prevent serious complications.
• Deep Vein Thrombosis (DVT): While DVT typically presents with swelling and pain in the leg, in rare cases, it can cause localized redness and warmth. It's a critical diagnosis to consider due to the risk of pulmonary embolism.
• Erythromelalgia: A disorder that causes burning pain, heat, and redness in the hands and feet. It can be primary or secondary to other conditions like myeloproliferative disorders.

Rare Diagnoses

• Erysipelas: A type of skin infection that involves the upper dermis, typically caused by beta-hemolytic group A streptococci. It presents with well-demarcated, bright red, warm, and tender skin lesions.
• Complex Regional Pain Syndrome (CRPS): A condition characterized by chronic pain, inflammation, and hypersensitivity after an injury or trauma. It can cause changes in skin temperature and color, among other symptoms.
• Sarcoidosis: A systemic disease that can cause granulomatous inflammation in various parts of the body, including the skin. Skin manifestations can include nodules, plaques, and rarely, localized redness and warmth.