Bacterial Facial Cellulitis: This is the most common cause of facial cellulitis, typically resulting from streptococcal or staphylococcal infections. The justification for this being the single most likely diagnosis is based on its high prevalence and the commonality of bacterial infections in the facial area.

Erysipelas: A type of superficial cellulitis caused by streptococcal bacteria, characterized by a well-demarcated, raised edge. It's likely because it presents similarly to facial cellulitis but has distinct clinical features.
Impetigo: A contagious skin infection that can lead to cellulitis if not treated. It's a likely diagnosis, especially in children, due to its contagious nature and potential to spread and complicate into cellulitis.
Folliculitis: An inflammation of the hair follicles, which can sometimes progress to cellulitis. This is considered likely due to its potential to evolve into a more severe infection like cellulitis, especially if caused by more virulent bacteria.

Ludwig's Angina: A severe infection of the tissues in the neck, which can cause significant swelling and potentially life-threatening airway obstruction. It's crucial not to miss this diagnosis due to its high morbidity and mortality if not promptly treated.
Cavernous Sinus Thrombosis: A rare but potentially life-threatening condition that can occur as a complication of facial infections, including cellulitis. The risk of severe complications, including death, makes it a diagnosis that must not be missed.
Orbital Cellulitis: An infection of the tissues surrounding the eye, which can lead to serious complications, including vision loss. The potential for severe and permanent damage necessitates its inclusion as a "do not miss" diagnosis.

Actinomycosis: A rare chronic bacterial infection that can cause abscesses and lesions in the face and neck. It's considered rare due to its low incidence and the fact that it's often mistaken for other conditions.
Nocardiosis: A rare infection caused by Nocardia bacteria, which can affect the skin and other parts of the body. Its rarity and the fact that it often affects immunocompromised individuals make it a less common consideration in the differential diagnosis of facial cellulitis.
Mycobacterial Infections: Including tuberculosis and leprosy, which can cause skin lesions and infections that might mimic cellulitis. These are rare in many parts of the world and are typically considered in patients with specific risk factors or exposure histories.