Sebaceous Cyst

Limited experience with humans has shown that exposure to even small amounts of the higher chlorinated derivatives, particularly hexachlorodiphenyl oxide, may result in appreciable acneform dermatitis. Chloracne is usually persistent and affects the face, ears, neck, shoulders, arms, chest, and abdomen (especially around the umbilicus and on the scrotum). The most sensitive areas are below and to the outer side of the eye (malar crescent) and behind the ear. The skin is frequently dry with noninflammatory comedones and pale yellow cysts containing sebaceous matter and keratin. 

Sebaceous cysts are benign retention cysts of sebiun. They often appear in the geriatric population due to aging. Milia are small (0.5 mm), round, sebaceous cysts that tend to remain intracutaneous (Figure 23-24). They are common on the eyelids, are whitish in color, are found away from the lid margin, and cause little irritation.They are important only from a cosmetic standpoint. 

Subcutaneous sebaceous cysts are yellowish in color, may be larger than milia (up to 10 to 12 mm), are asymptomatic, and are firm to the touch (Figure 23-25). The capsule and its contents are moveable under the overlying skin. Often the plugged orifice of the gland duct is visible. 

Subcutaneous sebaceous cysts must be removed by total excision, because simple incision usually results in recurrence. 

Deep cystic acne is a complex condition that involves an interaction between hormones (testosterone), sebum, and bacteria. It starts at puberty when the increase in androgen levels causes greater activity of the sebaceous glands. This leads to increased growth of epidermal tissue, which blocks the follicle and creates a comedo (cyst) composed of sebum, keratin, and bacteria. Irritation of the follicular wall follows, with rupture of the follicle and then an acute inflammatory reaction. This leads to an abscess and finally healing with scar tissue. 

In 1982 the Food and Drug Administration (FDA) approved the oral use of isotretinoin (Accutane) for the treatment of severe nodulocystic acne that has not responded to antibiotics. This drug is not active topically. As the name suggests, isotretinoin is an isomer of tretinoin. The only structural difference between the two molecules lies in the spatial arrangement of the atoms around one carbon-carbon double bond. Isotretinoin has the chemical name 13-cA-retinoic acid. Through mechanisms not well understood, it decreases the size of the sebaceous glands and inhibits closure of the pore. These actions may diminish the ultimate formation of cysts. As is... 

In the vast majority (88%), dermoid cysts are uni-lociflar cystic lesions filled with sebaceous material. A protuberance, the Rokitansky nodule, or dermoid plug, projects into the cavity and is the hallmark of dermoids (Fig. 9.17). It contains a variety of tissues, often including fat and calcifications, which represent teeth or abortive bone. Fat is detected in over 90%,... 

Cysts filled with sebaceous and keratinaceous debris have also been described (Ross 1948). Crow found that straw-colored cysts, which were typical of chlor-acne, were rarely seen in pitch workers (Crow 1970). In a different series, sebaceous retention cysts and... 

These lesions result from the proliferation of epidermal cells within a circumscribed space of the dermis. They are composed of keratin producing epithelium and can be distinguished from dermoid cysts, which contain skin and skin appendages, and from sebaceous cysts. 

Sebaceous cysts are found most commonly on the scrotum, but can be found on the penile shaft as well. Usually they do not require treatment. Surgical excision can be indicated when they continue to grow or become unsightly, painful and infected. Infected cysts may require oral antibiotics or other treatment before excision. 

At ultrasound sebaceous cysts present as homogeneously hypoechoic or relatively echogenic nodules within the dermis, with well-defined margins (Fig. 20.2). No vascular signals are recorded at color Doppler interrogation. Infected sebaceous cysts may present with increased vascularity of the surrounding soft tissue. 

Fig. 20.2. Axial scan. Sebaceous cyst of the penis presenting as a homogeneously echogenic lesion ( )...

Soft tissue masses of the subcutaneous tissue include a variety of lesions, such as calcifications, tophaceous gout or rheumatoid nodules, sebaceous cysts... 

Malherbe A, Chemantais J (1880) Note sur I pith lioma calci-fie des glandes sebac es. Prog Med 8 826-837 Maxwell AJ, Mamtora H (1990) Sonographic appearance of epidermoid cyst of the testis. J Clin Ultrasound 18 188-190... 

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