Primary Lymphedema (2011)

Sir:FigurePrimary lymphedema is currently divided into categories based on age of onset: congenital, praecox, or tarda. This classification is problematic because (1) the age ranges of the periods are not well-defined, (2) the terminology is imprecise, and (3) patients are not separated according to developmental age. Consequently, communication and research are impeded. Congenital lymphedema has been defined as swelling noted at birth, birth or “shortly thereafter,” birth to 3 months, birth to 1 year, or birth to 2 years. Praecox has been used for lymphedema onset from birth to 35 years, anytime after birth, after birth to 24 years, after birth to 35 years, 4 months to 20 years, or 1 year to 35 years. Tarda has described lymphedema developing after 20 years or after 35 years. Because congenital, praecox, and tarda have inconsistent age ranges, categorizing patients is difficult. For example, some authors may consider a 6-month-old infant presenting with lymphedema to be a congenital case, whereas others would place the child into the praecox group.1–3 Similarly, a 22-year-old patient with new-onset idiopathic lymphedema could be called praecox or tarda.1–3 Not only are the periods congenital, praecox, and tarda poorly defined, but the use of these terms to describe age ranges is imprecise. A congenital anomaly may not manifest at birth; a child or adolescent who develops primary lymphedema was born with malformed lymphatics. Praecox is synonymous with early and is relative to another time point, it does not describe an age range. For example, a 1-day-old child with congenital lymphedema is praecox to a 1-month-old infant with lymphedema, although both would be labeled congenital lymphedema under the current classification system. Similarly, tarda is used to describe late lymphedema, but a 1-month-old child with lymphedema is tarda to a 1-day-old neonate. The traditional classification of primary lymphedema also does not have a biological basis; praecox contains infants, children, adolescents, and adults. The onset of primary lymphedema, like other pediatric conditions, should be categorized depending on the patient's developmental age: infancy (birth to 12 months), childhood (1 to 8 years for girls and 1 to 9 years for boys), adolescence (9 to 21 years for female subjects and 10 to 21 years for male subjects), and adulthood (>21 years).4,5 Categorizing the onset of primary lymphedema by developmental age provides a well-defined system that is physiologically accurate; adolescence is separated from childhood and adulthood based on endocrine stimuli that lead to sexual maturation. Although a genetic cause is known for some types of primary lymphedema, the reasons why patients develop the condition at different times is unclear. Comparison of onset, progression, and morbidity between adolescence and other periods may provide insight into the pathophysiology of the disease. Under the current system, this analysis is not possible because infants, children, adolescents, and adults are categorized into one group (i.e., praecox). Defining the onset of primary lymphedema by developmental age would improve communication and facilitate research (Table 1).Table 1: Onset of Primary LymphedemaArin K. Greene, M.D., M.M.Sc. Carolyn C. Schook, B.A. Department of Plastic and Oral Surgery, Vascular Anomalies Center and Lymphedema Program, Children's Hospital Boston, Harvard Medical School, Boston, Mass. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article.