Patchy dermal hypoplasia as a characteristic feature of Proteus syndrome
R. Happle, P. M. Steijlen, U. Theile, D. Karitzky, S. Tinschert, H. Albrecht-Nebe and W. Kuster
Department of Dermatology, Philipp University, Marburg, Germany.
BACKGROUND: The diagnostic criteria of Proteus syndrome include various
lesions of localized overgrowth such as digital gigantism, hemihyperplasia
with unilateral macrocephaly, epidermal nevus, and mesodermal hamartomas
such as lipoma, lymphangioma, hemangioma, or fibroma. Hyperplasia of the
plantar dermal tissue may result in a characteristic cerebriform
appearance. However, hypoplastic lesions involving various tissues such as
subcutaneous fat or muscles also may be observed in this syndrome. This
paradoxical phenomenon has so far been underestimated, and the presence of
circumscribed lesions of dermal hypoplasia has been entirely ignored.
OBSERVATIONS: We report 4 cases of Proteus syndrome associated with large
patches of dermal hypoplasia, resulting in a more prominent appearance of
venous vasculature. CONCLUSIONS: Patchy dermal hypoplasia appears to be a
characteristic feature within the spectrum of Proteus syndrome. The anomaly
should not be confused with partial lipohypoplasia that may likewise be
associated with this multisystem birth defect. From a review of the
literature, we conclude that patchy dermal hypoplasia may have occurred in
several previous cases. In the future, recognition of this cutaneous
anomaly may help to establish the diagnosis in otherwise doubtful cases. To
explain the coexistence of lesions of dermal hyperplasia and hypoplasia, we
propose the genetic concept of "twin spotting." At the gene locus of
Proteus syndrome the embryo would carry 1 allele giving rise to dermal
overgrowth, whereas the corresponding allele would be responsible for a
diminished proliferation of cutaneous fibroblasts. Somatic recombination
may result in 2 different populations of cells homozygous for either
allele.
