Purpura: This condition is characterized by nonblanchable, purple spots that can appear anywhere on the body, including the lower extremities. It is often associated with bleeding disorders, platelet issues, or vasculitis, making it a common consideration for nonblanchable rashes.

Eczema (Dyshidrotic): Although typically blanchable, severe cases of eczema can lead to nonblanchable lesions due to intense inflammation and potential secondary infection.
Cellulitis: An infection of the skin and subcutaneous tissues, cellulitis can cause redness, swelling, and warmth, and in severe cases, may lead to nonblanchable areas due to compromised skin integrity.
Vasculitis: Inflammation of the blood vessels can cause a variety of skin manifestations, including nonblanchable rashes, due to the damage to the vessel walls.

Meningococcemia: A severe, life-threatening infection caused by Neisseria meningitidis, characterized by a nonblanchable rash (purpura fulminans), which requires immediate medical attention.
Disseminated Intravascular Coagulation (DIC): A condition that prevents the blood from clotting properly, leading to widespread clotting and bleeding, which can manifest as a nonblanchable rash among other symptoms.
Rocky Mountain Spotted Fever (RMSF): A tick-borne illness that can cause a nonblanchable rash, fever, and other systemic symptoms, requiring prompt diagnosis and treatment.

Leukocytoclastic Vasculitis: A form of vasculitis that affects small blood vessels and can cause nonblanchable purpura, though it is less common than other forms of vasculitis.
Thrombotic Thrombocytopenic Purpura (TTP): A rare blood disorder characterized by the formation of blood clots in small blood vessels throughout the body, which can lead to nonblanchable rash among other symptoms.
Henoch-Schönlein Purpura (HSP): A form of vasculitis that affects blood vessels and is characterized by a nonblanchable rash, typically seen in children, but can occur in adults as well.