Pruritus: The “Itchy” Patient

Pruritus of unknown origin (PUO)
- Neurotic excoriations (factitia)
- Pruritus of chronic renal disease
- Pruritus caused by liver disease
- Pruritus resulting from hypothyroidism
- Pruritus resulting from hyperthyroidism
- Pruritus resulting from Hodgkin’s disease
Clinical variants
- Aquagenic pruritus
- Notalgia paraesthetica
- Brachioradial pruritus

Overview

Pruritus, the most common symptom of all skin diseases, can be simply defined as an unpleasant sensation that elicits the urge to scratch.

Pruritus may result from the following:

Common primary skin disorders such as eczema, lichen simplex chronicus, xerosis, psoriasis, lichen planus, or, rarely, dermatitis herpetiformis
Exogenous causes such as drugs, contact dermatitis (e.g., poison ivy), scabies, lice, fiberglass, and aquagenic pruritus
Internal disorders such as chronic renal failure, acquired immunodeficiency syndrome, polycythemia vera, cholestasis, pregnancy-related disorders, primary biliary cirrhosis, diabetes mellitus, thyroid disease, and carcinoid syndrome
Psychogenic causes such as delusions of parasitosis, neurotic excoriations, pruritus ani, and obsessive-compulsive disorder
Associated malignant diseases such as Hodgkin’s disease, leukemia, and multiple myeloma

Pruritis of Unknown Origin

Basics

Pruritus of unknown origin (PUO) is itching for more than 2 to 6 weeks with no determined cause.

Description of Lesions

Linear excoriations, crusts, lichenified plaques, and wheals may be present.
Pruritus with no lesions is also quite common.
When lesions have bizarre appearances, facticia or “neurotic excoriations” should be suspected. (Fig. 15.1) (see also Chapter 2, “Eczema”).