Xerosis (Dry Skin): Given the patient's age, xerosis is a common condition that can cause generalized pruritis and a rash, particularly in elderly individuals due to decreased moisture in the skin.

Eczema (Atopic Dermatitis): A chronic condition that can cause pruritic rashes and is common in older adults, though it typically starts earlier in life.
Psoriasis: An autoimmune condition causing skin cells to build up and form scales and itchy, dry patches, which can occur at any age.
Allergic Contact Dermatitis: A skin reaction that occurs after contact with an allergen, which can cause a pruritic rash and is possible at any age.
Urticaria: Hives can cause pruritis and a rash, and while often acute, can be chronic in some cases.

Bullous Pemphigoid: An autoimmune disease that causes blistering of the skin and can be life-threatening if not treated promptly. It's more common in older adults.
Malignancy-Associated Pruritus: Certain cancers, like lymphoma or leukemia, can cause generalized pruritis without a clear rash, or with a subtle rash that might not be immediately recognized.
Thyroid Disease: Both hyperthyroidism and hypothyroidism can cause pruritus, and while not immediately life-threatening, are important to diagnose due to their impact on overall health.

Pityriasis Rubra Pilaris: A rare skin disorder that causes constant itching and scaling (exfoliation) of the skin, which can be challenging to diagnose.
Grover's Disease: A rare skin condition characterized by small, itchy bumps on the skin, more common in older men.
Sjögren's Syndrome: An autoimmune disorder that can cause dry skin and pruritus among other symptoms, though it's more commonly associated with dry eyes and mouth.