Dry Skin (Xerosis): This is a common condition, especially in older adults or during dry weather, leading to itchy papular rashes on the lower legs due to lack of moisture in the skin.
Eczema (Atopic Dermatitis): A chronic condition characterized by itchy, inflamed skin that can appear anywhere on the body, including the lower legs, often presenting as papular rashes.

Contact Dermatitis: An allergic or irritant reaction to substances like soaps, detergents, or metals, leading to itchy papular rashes on the lower legs.
Insect Bites: Reactions to bites from mosquitoes, fleas, or bed bugs can cause itchy papular rashes on the lower legs.
Keratosis Pilaris: A condition characterized by small, rough, sandpapery bumps on the skin, often on the legs, which can be itchy.
Stasis Dermatitis: Associated with venous insufficiency, leading to skin changes and itchy rashes on the lower legs.

Cellulitis: A bacterial skin infection that can present with redness, swelling, and warmth, but may initially appear as an itchy papular rash. It requires prompt antibiotic treatment.
Deep Vein Thrombosis (DVT): While not typically presenting as a papular rash, DVT can cause skin redness and swelling, and it's crucial to consider this diagnosis due to its potential for severe complications like pulmonary embolism.
Lymphoma: Certain types of lymphoma, like cutaneous T-cell lymphoma, can present with skin manifestations, including itchy rashes.

Pityriasis Rubra Pilaris: A rare skin disorder characterized by constant itching, and the formation of reddish-orange patches on the skin, which can include the lower legs.
Erythema Nodosum: A condition characterized by the sudden formation of painful, red nodules under the skin, often on the lower legs, which can be itchy.
Leukocytoclastic Vasculitis: A condition involving inflammation of the blood vessels, which can present with itchy, purpuric rashes on the lower legs.