Prenatal Sonographic Findings of Extensive Low‐Flow Mixed Lymphatic and Venous Malformations

Prenatal sonographic diagnoses of subcutaneous soft tissue masses include hemangiomas, malformations (capillary, lymphatic, venous, arterial, or mixed), teratomas, and, rarely, sarcomas. 1-5 Prenatally depicted malformations may be seen in association with more complex fetal conditions, including Klippel-Trenaunay-Weber (angio-osteohypertrophy) and Proteus syndromes.6"9 We present an unusual case in which extensive multiple soft tissue tumors encompassing the fetal upper chest, back, nuchal area, and bilateral axillae, considered consistent with multiple large lymphatic malformations noted at 23 weeks' gestation, decreased in size throughout the remainder of gestation. At delivery, relatively small subcutaneous masses remained. Tissue histopathologic findings obtained at biopsy and the neonate's clinical course during which the subcutaneous masses underwent a marked spontaneous decrease in size, were consistent with low-flow mixed lymphatic and venous malformations.