Giant Cell Arteritis (GCA): This condition often presents similarly to PMR but can have a higher WCC and neutrophil count due to its inflammatory nature. The presence of symptoms like temporal headaches, jaw claudication, and visual disturbances would support this diagnosis.

Infection: Bacterial or fungal infections can cause elevated WCC and neutrophils, and some infections (e.g., endocarditis, osteomyelitis) can present with systemic symptoms that might mimic PMR.
Malignancy: Certain cancers, such as multiple myeloma or lymphoma, can cause systemic inflammation and elevated WCC, potentially mimicking PMR.
Rheumatoid Arthritis (RA): Although RA typically has a different clinical picture, some patients can present with systemic symptoms and elevated inflammatory markers, including WCC and neutrophils.

Septic Arthritis or Osteomyelitis: These conditions are medical emergencies that require prompt diagnosis and treatment. They can present with localized pain and systemic inflammation, including elevated WCC and neutrophils.
Endocarditis: Infective endocarditis can cause systemic symptoms, including fever, malaise, and weight loss, along with elevated inflammatory markers.
Wegener's Granulomatosis (Granulomatosis with Polyangiitis, GPA): This is a form of vasculitis that can present with a wide range of symptoms, including systemic inflammation and elevated WCC.

Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Syndrome): A rare form of vasculitis characterized by asthma, eosinophilia, and vasculitic symptoms, which could potentially mimic PMR in some cases.
Relapsing Polychondritis: An autoimmune disorder that can cause inflammation of cartilaginous structures, leading to a variety of symptoms, including systemic inflammation.
Adult-Onset Still's Disease: A rare inflammatory disorder that can present with high fevers, rash, and arthritis, along with significantly elevated WCC and neutrophils.