Retiform hemangioendothelioma (RH) is a rare low-grade malignancy angiosarcoma, with a high rate of local recurrence and a low metastatic risk. A 6 year-old girl with a large cervical cystic lymphangioma diagnosed by ultrasound and Doppler ultrasound, which showed a large multiloculated anechoic cyst with no flow. The lymphangioma was treated with injections of Picibanil (OK-432). The tumor regressed, but after a year, she developed a poorly limited infiltrated plaque spreading out regularly over her chest, back, and shoulder. The biopsy showed a poorly limited dermal and subcutaneous vascular proliferation composed of elongated arborising vessels lined with ovoid endothelial cells in a hobnail pattern. In addition, the deep part of the lesion showed typical features of a papillary intralymphatic angioendothelioma pattern (PILA) or Dabska tumor. The endothelial cells strongly expressed podoplanin (D2-40). A diagnosis of RH with focal areas of PILA was reached. The girl died 8 months after surgery of hypovolemic shock in a context of diffuse lymphangiomatosis with pulmonary localization. To our knowledge, RH has hardly ever been described in children. This entity exhibits a continuum with the PILA, sharing not only morphological and immunohistochemical similarities but also its ability to develop in a context of a vascular anomaly, particularly a lymphangioma. The role of Picibanil in the development of this tumor can be discussed.