The pathologico-anatomical term adenoma still lacks both definiteness and circumscription. Some authorities extend it to include all increase of glandular epithelium, even when form and function are well preserved. Others limit the designation to an atypical increase with loss of function. It is not surprising, therefore, that the same confusion should exist with regard to the sebaceous adenomata of the skin. The affection is a rare one, and the opportunities for histological examination have not been numerous. A study of the literature, however, shows very plainly that two main pathological types may be distinguished. The first accords with Unna's definition: Benign, irregular, tumorous outgrowths of the sebaceous epithelium, going on to fatty, but not to corneous or colloid metamorphosis. The second is a simple hypertrophy of apparently normal sebaceous gland tissue.
Clinically, also, at least two types of sebaceous adenomata are to be recognized; they do not, however, correspond to