Pediatric Surgery, Al Azher University, Cairo, Egypt
Penile cysts are uncommon lesions, and in general, they are asymptomatic and usually do not interfere with urinary or sexual function, unless when they are complicated by infection or trauma, an occasional irregularity of the urinary stream encountered in some cases. Most of them are present since birth, but they are only detectable in adolescence or adulthood. Penile cyst classified into; acquired types or pseudocyst and true cyst which are usually congenital.
Several and misleading synonymous terms were given to penile cysts, including mucus cyst of the penis, genitoperineal cyst of the median raphe, parameatal cyst, hydrocystoma and apocrine cystadenoma of the penile shaft are also used in past.
Generally penile cysts are rare except the smegma collecting cysts (Chap. 36), which are a common lesion specially in countries practising circumcision routinely for almost all infants, also inclusion dermoid cysts are not rare during the last decades specially after hypospadias surgery and penile surgery for augmentation.
The clinical diagnosis is sometimes difficult to define the cyst type and nature, and differential diagnoses include rare types of cysts like pilonidal cysts, tyson glands cysts, and also should be differentiated from other cystic urethral swelling like urethral diverticulum. Penile cysts are usually a single midline swelling can be found mainly in the ventral surface of the shaft of the penis, rarely in the glans or the dorsum.
Acquired (false or pseudocyst):
Congenital (True cyst)
Congenital Dermoid Cyst (Fig. 19.7)
Dermoid cyst in the dorsum of the penis
Mucoid Cyst (Fig. 19.8)
True mucoid cyst at the coronal sulcus
Median raphe cyst (Fig. 19.9)
Large median raphe cyst at the coronal sulcus
Parameatal cyst (Fig. 19.10)
Flat small parameatal cyst at the glans penis
19.3 Smegma Cyst
Aggregation of smegma in circumcised child is not rare and may present as a yellowish cystic or doughy swelling of different sizes at the cut edges of the prepuce (Fig. 19.1), sometimes it acquire a large size disfiguring the penis (Fig. 19.2), it is usually liable for infection and traumatic rupture. In un-circumcised penis smegma may forms a small lump in the undersurface of the penis or prepuce, and rarely it may affect the dorsum of the penis. Careful excision with meticulous penile skin closure will avoid recurrence (Chap. 36)
19.4 Inclusion Dermoid Cyst
It is also called epidermoid cyst, or acquired dermoid cyst.
Historical Background Dermoid cyst of penile skin was described for the first time in a young Caucasian man by Tomasini et al. in 1997 .
Epidermoid cysts occur in a wide age range, but commonly detected at young age. The location of the lesion is commonly at the ventral aspect or the base of the penile shaft, epidermoid cyst arising from the glans penis has also been reported occasionally, The histopathology of an epidermoid cyst shows a unilocular cyst lined by stratified squamous and contains laminated keratin material in the cyst lumen (Figs. 19.3 and 19.4, 19.5 and 19.6). Epidermal cysts of the penis can be single or multiple and of variable size. Characteristically they have a tendency to grow slowly, but they can reach a big dimensions with time.
Etiology Epidermoid inclusion cyst may be:
Congenital due to sequestration of epidermal rests during embryonic life, and this type considered as a true epidermal inclusion cysts hence it appear early in a neonate, but may not discovered except at late childhood.
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