Beyond lymphedema, in its diverse manifestations, there is a spectrum of human disease that directly or indirectly alters lymphatic structure and function. Not surprisingly, the symptomatic and objective presentation of these patients is quite heterogeneous. Diagnosis and differential diagnosis pose distinct chal­lenges. In this overview, the various categories of lymphatic disease are enu­merated and viewed through the prism of lymphatic embryological development (Chap. 4).

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Lymphedema is unquestionably the most common diagnostic entity among the lym­phatic vascular diseases. It is encountered in both acquired and heritable forms.2 Traditionally, a distinction is drawn among primary and secondary causes of lym­phedema.4 In this schema, primary lymphedemas encompass both the sporadic and hereditary forms, as well as those that are syndrome associated; secondary lym­phedema is either malignant (i.e., associated with direct neoplastic invasion or obstruction of the vascular channels and nodes) or benign (acquired as a conse­quence of infection, trauma, or iatrogenic causes). More recent attitudes surround­ing lymphedema suggest that the boundaries may be blurred: primary cases often declare themselves after a “secondary” provocation, and evolving clinical data sug­gest that there might be a genetic predisposition for the development of lymphedema, even when the inciting secondary events are easy to identify.

A useful organizational schema is to classify the disorders by their autosomal dominant (Noonan syndrome, Adams–Oliver syndrome, and neurofibromatosis) or autosomal recessive (Hennekam’s syndrome, the Prader–Willi syndrome, and Aagenaes’ syndrome) modes of genetic transmission.

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