Sebaceous, mucous, dermoid and epidermoid cysts

C OMPARED to many types of neopIasms affecting the body, sebaceous, epidermoid, incIusion dermoid and mucous cysts are reIativeIy unimportant. However, since the majority of such tumors occur about the head and neck where they are unsightIy or at Ieast conspicuous, there is always a demand for the removal of such growths by surgica1 procedures which leave a minima1 amount of residua1 scarring. WhiIe some individuaIs apparently are unconcerned over such tumors unIess they are associated with an active inflammatory process, there is an increasing number of peopIe who seek medica advice about such growths because of the fear that they may be of a maIignant nature, Aside from the patient’s viewpoint, the remova of a11 such cysts is to be recommended because many are IikeIy to become acuteIy infected and suppurate for a Iengthy period of time and because in rare instances one wiI1 undergo a maIignant change. Mucous cysts, which are lined with cuboida1 or coIumnar epitheIium and contain a mucoid materia1, offer no diagnostic uncertainties on microscopic examination. However, many cysts of the sebaceous, epidermoid and dermoid varieties are diffrcuIt to distinguish because their histologic structure may be very simiIar and because there is no uniformity among pathoIogists as to the exact characteristics of these tumors. Broders and WiIson have found that practicaIIy a11 so-caIIed sebaceous cysts which are Iined with stratified squamous epithehum do not contain the fatty, sebaceous and odorous materia1 typica of a sebaceous gland but contain layer upon Iayer of nonfatty, odorIess (unIess infected) keratin. They, therefore, prefer to calI these keratin filled tumors “ keratomas.” (Fig. I.) A true inclusion dermoid cyst, which deveIops along the embryonic clefts and Iines of fusion, is Iined with stratified epithelium which possesses sebaceous and sweat glands and hair foIIicIes; the cheesy materia1 in such a growth is of a sebaceous character. In the stratified epitheIia1 Iining membrane of an epidermoid cyst, no hair foIIicIes or sebaceous or sweat glands are evident aIthough the cystic contents are sebaceous in nature. The majority of epidermoid cysts are congenital and deveIop in situations corresponding with those of incIusion dermoids. The former, therefore, are probably incIusion dermoid cysts rather than sebaceous cysts; certainIy, they are not keratomas. Confusion is added to this conception of epidermoid cysts since many pathoIogists consider a11 sebaceous cysts and keratomas as epidermoid tumors. For the sake of cIarity I prefer to recognize those cystic skin tumors whose contents consist of‘ keratin as “keratomas,” and those which are of acquired origin and which contain sebaceous material as “sebaceous cysts.” I consider “inclusion dermoids” to be congenital cysts deveIoping aIong the embr\onic Iines of fusion and containing hair foIIicIes and sweat and sebaceous gIands in their wails. “ Epidermoids” are similar in nature to dermoid cysts with the exception that their Iinings possess none of the previously mentioned derma1 structures. Although keratomas and sebaceous cysts may arise in the subcutaneous tissues of any part of the body, the majority occur in the scalp and in the lobe and on the posterior surface of the ear. In these regions they are frequently muItiple. Such tumors