Differential Diagnosis
- Single most likely diagnosis
- Cellulitis: The patient's symptoms of a warm, edematous, and red area in the groin, with spreading redness, are classic for cellulitis, a common bacterial skin infection. The absence of a recalled injury and the presence of systemic symptoms like vomiting and diarrhea (V, D) could indicate a systemic response to the infection.
- Other Likely diagnoses
- Folliculitis: An infection of the hair follicles, which could present similarly to cellulitis, especially if the patient has not shaved or has ingrown hairs in the area.
- Abscess: A localized collection of pus that could cause redness, warmth, and swelling, although typically, an abscess is more localized and may have a fluctuant center.
- Contact Dermatitis: An allergic or irritant reaction to something that came into contact with the skin, which could cause redness, swelling, and warmth, although it usually doesn't spread as rapidly as described.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Necrotizing Fasciitis: A severe infection that destroys the tissue under the skin, including fat and the tissue covering the muscles (fascia). It's a medical emergency and can be fatal if not treated promptly. The presence of severe pain out of proportion to the appearance of the skin, fever, and systemic symptoms like vomiting could suggest this diagnosis.
- Erysipelas: A type of skin infection that involves the upper layer of the skin and can spread rapidly. It's usually caused by streptococcal bacteria and can lead to serious complications if not treated.
- Rare diagnoses
- Erythema Nodosum: An inflammatory condition characterized by the formation of nodules under the skin, typically on the shins. It could be considered if the patient's symptoms were more nodular and less diffuse.
- Deep Vein Thrombosis (DVT): Although DVT typically presents with swelling, warmth, and redness of the leg, it's usually more localized to the area around a vein and is accompanied by pain and swelling that worsens throughout the day. The absence of a recalled injury or recent immobilization makes this less likely but not impossible.