A 7-year-old boy had partial lipohypoplasia and patchy dermal hypoplasia involving large areas of his body. These areas of deficient growth were similar to those described in many cases of Proteus syndrome. Paradoxically, however, he had only few and rather mild lesions of disproportionate overgrowth. This unusual case is taken as a clue to postulate the Elattoproteus syndrome, an inverse form of Proteus syndrome. The paradoxical coexistence of hyperplastic and hypoplastic lesions may reflect a twin spot phenomenon. The patient would carry at the Proteus locus one allele giving rise to overgrowth of tissues (Pleioproteus allele--from Greek pleion, meaning plus), whereas the other allele would cause deficient growth of tissues (Elattoproteus allele--from Greek elatton, meaning minus). At an early stage of embryogenesis, somatic recombination would give rise to two different populations of cells homozygous for either allele. From a heuristic point of view, one may postulate the existence of the Elattoproteus syndrome, a purely inverse form of Proteus syndrome that would develop in the absence of the Pleioproteus allele.