Median raphe cysts are rarely seen cysts that develop from the median raphe in the male external genital region. Although these cysts were first identified decades ago, <200 cases have been reported to date, mostly in case reports with <15 cases reported in the Indian subcontinent. Histopathological linings for these cysts should be distinguished from apocrine cystadenomas, mucinous cysts, and epidermal cysts. Clinicians and pathologists acquainted with these infrequent cysts having typical localization are in favored position to clinch the diagnosis and elucidate the still enigmatic genesis of these cysts.
A 36-year-old male noticed a swelling on his penis for the past 3 months. It was not painful. He had no history of burning micturition. There was no history of discharge per urethra or fever. On examination, it was a cystic swelling present in the foreskin of the penis on the ventral aspect and close to the frenulum. Under local anesthesia, circumcision was performed.
Excised skin-covered tissue measured 8 cm × 1.5 cm × 0.3 cm with a cystic swelling in the center measuring 0.5 cm in diameter. On cutting open the cyst, it let out pus-like material. Cyst wall thickness was 0.1 cm with inner cyst wall appearing gray white.
Microscopy showed skin-lined tissue with a cyst in the dermis lined by flattened to cuboidal to stratified cuboidal benign epithelium [Figures 1 and 2]. Lumen contained no material. Surrounding subepithelial tissue showed chronic inflammatory infiltrate. Based on the site and histological features, a diagnosis of median raphe cyst of the penis was given.
Median raphe cysts are cysts that develop on the median line in the male genital region in any area from the anus to the external meatus.
Median raphe cysts mostly present at birth and may remain asymptomatic or ignored during childhood. As the patient grows older, the cyst may also progress slowly. Later in adolescence or adulthood, the cyst may appear as a solitary and movable cystic nodule on the ventral surface of the penis. Although they are referred to as “median raphe cysts,” they can also present as cord-like or canaliform indurations on the median raphe, which are very rare. These unusual cysts are brought forward to the clinician by the parents during childhood, or they show up later in their 20s and 30s because they developed symptoms (infections or trauma), or mostly for cosmetic reasons. Thus, it gives a bimodal pattern of presentation. The differential diagnosis that the clinician should be keep in mind is glomus tumor, dermoid cyst, pilonidal cyst, epidermal inclusion cyst, urethral diverticulum, and steatocystoma. A well-informed clinician can make the diagnosis based on the characteristics of the cysts & based on the site, i.e., along the midline of ventral side of the male genital area from the urethral meatus to the anus and the perineum.
There are several possible explanations for the origin of these cysts. The first possible cause is embryologic defective closure of the median raphe. The second theory put forward is anomalous development of ectopic periurethral glands of Littre. The third theory, hypothesized by Paslin, is an anomalous sprouting and subsequent separation of the urethral columnar epithelium from the urethra.
Previous studies have shown four histopathological types of median raphe cysts. These include urethral, epidermoid, glandular, and mixed. The most common type of lining is urethral type which has stratified layers of uniform small cells overlaid by columnar epithelium, resembling urothelial lining. Epidermoid type contains stratified squamous epithelium, whereas glandular type contains intraepithelial glandular structures within the urothelial lining. Mixed type is the second most common cysts and contains more than one type of epithelium.
The present case showed cyst lined by flattened to cuboidal to stratified cuboidal benign epithelium which is the urethral type.
Treatment should be considered for the symptomatic lesions and for cosmetic purposes. The treatment options include a wide local excision and aspiration if the patient is not willing to undergo surgery. Aspiration alone is not recommended.
Unaccompanied clinical details and unambiguous clinical suspicion with multifarious histopathological picture of this rare type of penile cyst may even confound a well-trained pathologist.
In this case report, the clinician did not include median raphe cyst in their differentials. This highlights ever more the eminence of knowledge of median raphe cysts.
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