Insect Bites or Flea Bites: These are common causes of indurated itchy bumps, especially if the patient has been outdoors or exposed to pets. The bites can cause a localized allergic reaction, leading to itching and induration.

Allergic Contact Dermatitis: This condition occurs when the skin comes into contact with an allergen, causing an immune response that leads to itchy, indurated bumps. Common allergens include nickel, latex, and certain plants.
Keratosis Pilaris: A skin condition characterized by small, rough, itchy bumps on the skin, often on the arms, legs, or buttocks. It is caused by the accumulation of keratin, a protein that protects the skin.
Eczema (Atopic Dermatitis): A chronic skin condition that causes dry, itchy, and inflamed skin. It can lead to the formation of indurated bumps, especially if the skin is scratched or rubbed.

Cutaneous T-Cell Lymphoma (Mycosis Fungoides): A rare type of skin cancer that can cause indurated, itchy bumps. It is essential to consider this diagnosis, as early detection and treatment can improve outcomes.
Bullous Pemphigoid: An autoimmune disease that causes blistering of the skin, which can lead to indurated, itchy bumps. It is more common in older adults and can be life-threatening if left untreated.

Sarcoidosis: A condition that causes the formation of granulomas (inflammatory cells) in various parts of the body, including the skin. It can lead to indurated, itchy bumps, but this is a rare presentation.
Erythema Nodosum: A condition characterized by the formation of painful, indurated nodules on the skin, often on the legs. It can be caused by various factors, including infections, medications, and systemic diseases.