Cutaneous metaplastic synovial cyst in an Ehlers-Danlos patient.

Metaplastic synovial cyst is a recently reorganized entity characterized by a cystic space lined by polygonal cells and villous structures resembling synovium pointing toward the lumen. It usually develops following trauma. We report a 15-year-old girl with Ehlers-Danlos syndrome who developed a nodular lesion of her elbow without previous trauma. Histopathological and immunohistochemical studies yielded results similar to those reported in cases of cutaneous metaplastic synovial cyst. This case appears to be the first one reported of cutaneous metaplastic synovial cyst associated with an Ehlers-Danlos syndrome. Cutaneous fragility and anomalous scarring typical of Ehlers-Danlos syndrome may be related to the development of this pseudocyst. If so, other connective-tissue diseases with increased skin fragility could be susceptible to development of such lesions.