Dry Skin (Xerosis): This is a common condition that can cause intermittent pruritus, especially in areas like the legs. The lack of obvious skin changes supports this diagnosis, as dry skin may not always be visibly apparent.

Eczema (Atopic Dermatitis): Although it can present with visible skin changes, mild cases might not have noticeable alterations, and the pruritus can be intermittent.
Contact Dermatitis: This could be due to an allergic reaction or irritant exposure that occurs periodically, leading to pruritus in the same area without visible changes if the reaction is mild or if the exposure is brief.
Keratosis Pilaris: A condition characterized by rough patches on the skin, which can sometimes cause pruritus, especially if the skin is dry.

Neurological Conditions (e.g., Neuropathy, Multiple Sclerosis): Certain neurological conditions can cause pruritus without skin changes due to nerve damage or dysfunction. Missing these diagnoses could lead to delayed treatment of a serious underlying condition.
Internal Diseases (e.g., Liver or Kidney Disease, Hematological Disorders): Pruritus can be a symptom of various internal diseases. Although less common, these conditions are critical to identify due to their potential severity and the need for specific treatments.
Malignancy (e.g., Lymphoma): In rare cases, pruritus can be a presenting symptom of malignancy. Identifying and treating cancer early is crucial for prognosis.

Brachioradial Pruritus: A condition characterized by intense pruritus on the arms but can occasionally affect the legs, often without visible skin changes. It's thought to be related to nerve damage or compression.
Notalgia Paresthetica: A condition that causes pruritus and other sensations in the skin of the upper back but can occasionally affect other areas, including the legs, due to nerve irritation.
Cholestasis of Pregnancy: Although this would be specific to pregnant women, it's a rare cause of pruritus without skin changes, related to liver function alterations during pregnancy.