Populations affected:
(1) It is endemic in Brazil, adjacent South American countries (Bolivia, Columbia, Peru, Venezuela), and Tunisia
(2) It usually affects rural farmers or jungle dwellers.
(3) It tends to affect children and young adults with a peak incidence in the adolescents and adults in their 20's.
(4) Familial cases are fairly common.
(5) Residence in an endemic area for several months or years is required for a person to be at risk, with little risk from short exposures.
Clinical features:
(1) Presence of subcorneal blisters, which may be associated with feelings of pain or burning.
(2) Nikolsky sign is positive (bullae spread when pressure is applied with the finger).
(3) It may be acute, chronic, relapsing or recurrent.
(4) It may be localized or generalized. Generalized disease may be bullous-exfoliative, exfoliative-erythrodermic or disseminated keratotic plaques.
(5) Hyperpigmentation may occur in cases in remission.
(6) The disease may be exacerbated by exposure to the sun or heat.
(7) Mucosal lesions are uncommon, apparently due to the presence of desmoglein-3 in these areas as opposed to desmoglein-1.
(8) Neonates born to affected mothers do not show disease (infants born to mothers with pemphigus vulgaris may show "pemphigus neonatorum"), which has also been linked to the presence of desmoglein-3 in the skin of the neonates.
Pathologic and laboratory findings:
(1) Acantholysis occurs below the stratum corneum with intraepithelial vesicle formation below the stratum corneum.
(2) There is positive immunostaining for IgG in the areas of acantholysis.
(3) Serum contains autoantibodies to desmoglein 1, with titers rising prior to appearance of new lesions.
Prognosis:
(1) Patients usually respond well to oral prednisone. Complications of steroid therapy such as superinfection are an important cause of death.
(2) A small percentage of patients may have a spontaneous remission.
(3) Some patients develop Kaposi's varicelliform eruption (due to Herpes simplex, pages 662 and 666, Diaz) which can be fatal.
