The World Health Organization classified lipoma and lipomatous lesions as follows in the year 2002 based on histopathological appearance of the lesions.
BENIGN LIPOMATOUS TUMORS
LIPOMA: A lipoma is a benign tumor composed of mature white adipocytes and is the most common soft tissue mesenchymal neoplasm in adults, usually a circumscribed, non-encapsulated aggregate with clear cytoplasm, absence of vascularity and atypia of metaplasia.
LIPOMATOSIS: (Madelung disease, Launois-Bensaude syndrome): Lipomatosis is a diffuse overgrowth of mature adipose tissue. It occurs in a variety of clinical settings and can affect different anatomic regions of the body. Diffuse lipomatosis usually occurs in individuals under 2 years of age but it may also arise in adults.
ANGIOLIPOMA: A subcutaneous nodule consisting of mature fat cells, intermingled with small and thin-walled vessels, a number if which contain fibrin thrombi. Angiolipomas most frequently present as multiple subcutaneous small nodules, usually tender or painful. There is no correlation between the intensity/occurrence of pain and the degree of vascularity.