Final answer:
The nurse practitioner likely suspects erysipelas, a skin infection causing a hot, red, and well-demarcated lesion on the cheek, due to its characteristic appearance and accompanying systemic symptoms like fever.
Step-by-step explanation:
The patient presenting with a sudden onset of a large hot and indurated red skin lesion on the cheek with clear demarcated margins, accompanied by fever and elevated heart rate, leads the nurse practitioner to suspect erysipelas. This condition is an infection involving the upper dermis, typically caused by Streptococcus pyogenes, and it often presents with a raised rash that has clear borders. The systemic symptoms such as fever and tachycardia support the diagnosis of an acute infection, and erysipelas is known for its sharply defined edges and fiery red coloration. The approach to treatment involves antibiotics targeting the responsible bacteria.