Case report
Mibelli revisited: A case of type 2 segmental porokeratosis from 1893

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In autosomal dominant skin disorders, a pronounced mosaic involvement may sometimes be found to be superimposed on the ordinary nonsegmental lesions. Such “type 2 segmental manifestation” reflects loss of heterozygosity occurring at an early developmental stage, giving rise to a cell clone that lacks the corresponding wild-type allele. Here, this genetic concept is applied to an unusual case of plaque-type porokeratosis of Mibelli (PM) as published in 1893 by Vittorio Mibelli in the International Atlas of Rare Skin Diseases. The right forearm and hand of the 21-year-old patient showed a pronounced linear porokeratosis that had developed since the age of 2 years. Moreover, nonsegmental lesions of PM involved both hands and forearms as well as the face and the neck, having first been noticed at the age of 7 years. Two siblings and the father were likewise affected with PM. Hence, Mibelli's case from 1893 meets all of the criteria of a type 2 segmental manifestation of an autosomal dominant skin disorder. Recognizing such cases of superimposed segmental involvement may help elucidate the molecular basis of PM.

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The case report by Vittorio Mibelli

The report is presented in a German, English, and French version and describes a young man, “age 21, unmarried, of a well-to-do family of Parma”. Mibelli gives a detailed description of the patient's porokeratosis. The ailment shows a pronounced unilateral involvement and, in addition, less severe bilateral disseminated lesions.

References (22)

  • V. Mibelli

    Ueber einen Fall von Porokeratosis mit Localisation im Munde und an der Glans

    Arch Dermatol Syph (Vienna)

    (1899)
  • Funding sources: None.

    Conflicts of interest: None declared.

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