Which of the following statement about the primary lymphedema is NOT TRUE?

Primary Lymphedema: It has been generally been classified on the basis of the age of onset and presence of familial clustering. Primary lymphedema with onset before the age first year (with in two year according to L & B) of life is called is called congenital. The familial version of congenital lymphedema is known as Milroy's disease and is inherited as a dominant trait. Primary lymphedema with onset between the age of 1 and 35 years (b/w 2-35 according to L& B) is called lymphedema praecox. The familial version of familial praecox is known as Meige's disease. Primary lymphedema with onset after the age of 35 years is called lymphedema tarda. The primary lymphedema are relatively uncommon, occurring in 1 of every 10,000 individuals. The most common form of primary of lymphedema is praecox, which accounts for about 80% of the patients. Congetital and tarda lymphedemas each account for the remaining 10%. Lymphangiosarcoma is rare tumor that develops as a complications of long-standing ( usually more than 10 years) lymphedemas. Clinically, patients present with acute worsening of the edema and appearance of subcutaneous nodules that have a propensity towards hemorrhage and ulceration. The tumor can be treated, as other sarcomas, with preoperative chemotherapy and radiation followed by surgical excision, which usually takes the form of radical amputation. Overall, the tumour has a poor prognosis. Ref: L & B 25/e, page 949-50 ; Sabiston 18/e, page 2021-25