The passage discusses the clinical overlap between Proteus syndrome and Klippel-Trenaunay syndrome in a patient. Proteus syndrome is characterized by asymmetrical overgrowth, increased stature, macrodactyly, and soft tissue hypertrophy, while Klippel-Trenaunay syndrome includes port wine staining, limb hypertrophy, and venous thrombosis. The patient presented with features of both syndromes, including hemihypertrophy, macrodactyly, epidermal naevi, port-wine staining, and angiomatous naevi. The complete syndactyly of the toes and the absence of plantar soft tissue hypertrophy were more consistent with Klippel-Trenaunay syndrome. Recurrent venous thrombosis supported this diagnosis, though it occurred in the unaffected side. The overlap raises the possibility of a common etiological mechanism, possibly somatic mosaicism for a mutation in a growth factor or regulator gene. The diagnostic criteria for Proteus syndrome are not fully established, making it unclear whether the patient should be labeled as having Proteus syndrome or a true overlap between the two syndromes.The passage discusses the clinical overlap between Proteus syndrome and Klippel-Trenaunay syndrome in a patient. Proteus syndrome is characterized by asymmetrical overgrowth, increased stature, macrodactyly, and soft tissue hypertrophy, while Klippel-Trenaunay syndrome includes port wine staining, limb hypertrophy, and venous thrombosis. The patient presented with features of both syndromes, including hemihypertrophy, macrodactyly, epidermal naevi, port-wine staining, and angiomatous naevi. The complete syndactyly of the toes and the absence of plantar soft tissue hypertrophy were more consistent with Klippel-Trenaunay syndrome. Recurrent venous thrombosis supported this diagnosis, though it occurred in the unaffected side. The overlap raises the possibility of a common etiological mechanism, possibly somatic mosaicism for a mutation in a growth factor or regulator gene. The diagnostic criteria for Proteus syndrome are not fully established, making it unclear whether the patient should be labeled as having Proteus syndrome or a true overlap between the two syndromes.