3. A 62-year-old woman complained bitterly of itching on the soles of both feet. Both insteps are covered with discrete, confluent papules and tiny pustules on an erythematous and hyperpigmented (brown), sharply demarcated, and highly symmetrical base. No such lesions appear elsewhere.
Diagnosis: Palmoplantar pustulosis is the term most often used to describe a fairly common form of psoriasis typified by this case. Many patients are genetically predisposed to psoriasis, but they may require a trigger to set it off, such as strep infection or occasionally, medication. Notable among the latter are the b-blockers and lithium. Stress is often involved as well.
The bilateral symmetrical involvement of both insteps is highly suggestive of this diagnosis, which often also affects either peripheral or central palms. A secondary form of neurodermatitis (itch–scratch–itch cycle) can follow, complicating the picture and perpetuating the problem.
For more information, see “Pruritic Rash on Both Soles.” Clin Rev. 2012 Jan;22(1).