Localization of dermal edema in lipodermatosclerosis, lymphedema, and cardiac insufficiency. High-frequency ultrasound examination of intradermal echogenicity.

BACKGROUND: Chronic edema in venous insufficiency is associated with leg ulceration, whereas in lymphedema skin ulceration is less frequent and edema from cardiac failure does not cause major skin changes. The reason for these differences is unclear.
OBJECTIVE: Our purpose was to investigate, by means of ultrasound, the distribution of intradermal fluid in patients with edema associated with lipodermatosclerosis, lymphedema, or cardiac insufficiency.
METHODS: Sixteen patients with lipodermatosclerosis, 10 with lymphedema, 16 with leg edema from heart insufficiency, and 16 healthy control subjects were studied. Ultrasound images were obtained with a 20 MHz scanner. The echogenicity of the dermis was quantified by image analysis and the echogenicity of the upper (subepidermal) and lower portions of the dermis were measured.
RESULTS: In any type of edema the dermal echogenicity was lower than that of the control group, indicating intradermal edema. In normal skin the upper dermis was only slightly less echogenic than the lower dermis. In patients with lipodermatosclerosis a low-echogenic area was present in the upper dermis, which suggests the papillary dermis as a preferential site of edema formation. In contrast, in lymphedema dermal echogenicity was uniformly distributed, whereas in patients with heart failure the lower portion of the dermis was less echogenic than the upper dermis.
CONCLUSION: This study demonstrates that intradermal echogenicity shows characteristic patterns in different types of edema, which indicates that localization of fluid varies in the dermis, from subepidermal (lipodermatosclerosis), uniform (lymphedema), to deep dermal (heart failure). These differences may help in understanding the origin of different skin sequelae of edema.