Prenatal diagnosis of 'true tail' with cartilage content?

A human tail is a rare congenital anomaly with a prominent lesion from the lumbosacrococcygeal region. According to Dao and Netzky human tails are classified into 'true tails' and 'pseudotails'. True tails comprise only mesenchymal tissue (adipose, connective, muscle, nerve tissue, blood vessels, and cutis). They are presumed to be remnants of the embryologic tail. All other lumbosacrococcygeal protrusions are summarized as pseudotails. Superficially they may resemble true tails. They contain normal or abnormal tissue, e.g. cartilage, lipoma and glioma. We report a case of prenatal diagnosis of a human tail in association with omphalocele, hydrocephalus and antiphospholipid-antibody syndrome resulting in a severe fetal growth restriction. Due to cartilage content the appendage had to be classified as 'pseudotail'. However, anatomical position and the decrease of length observed by consecutive ultrasound examinations at 14 and 21 weeks of gestation was suggestive of delayed regression of a 'true tail'. Furthermore, the association of antiphospholipid-antibody syndrome with congenital malformations is discussed.