Mermet first reported a case of MRC in “Revue de Chirurgie” [1]. MRCs present with a bimodal age distribution at approximately 1–10 and 21–40 years old. MRCs were previously designated with multiple terms such as mucoid cyst of the penile skin, genitoperineal cyst of the median raphe, parameatal cyst, hydrocystoma and apocrine cystadenoma [2].MRCs mostly present at birth and may remain asymptomatic or unrecognized during childhood. 25.5% of all cases are diagnosed within the first decade of life [3]. Due to the fact that the majority of children (up to 75% of all cases) are asymptomatic, it has been suggested that MRCs are more common than it is considered [4].

Infection and trauma are the main causes that lead to rapid development of MRCs or clinical manifestation [5]. Other causes include rupture of a cyst or ulcer’s development on the surface of MRCs. Pain during sexual intercourse or even rarely discomfort during urination, especially when the cyst is located near the urethral meatus, are the main symptoms. Staphylococcus aureus and Neisseria gonorrheae are commonest pathogens that cause infection of MRC [6].

MRCs should be differentially diagnosed from other conditions such as epidermal inclusion cyst, pilonidal cyst, dermoid cyst and urethral diverticulum.Especially in cases of perianal localization, differential diagnosis should include condyloma, viral wart, hemorrhoid, hypertrophied papilla, glomus tumor and steatocystoma.

Case Reports

Case 1-A 3 year old boy presented with congenital multiple whitish cysts along a cord-like swelling running in the midline extending from the anterior margin of the anus to the lower pole of the scrotum. (Figure 1) The lesions spread along the perineal raphe. Infant showed no signs of pain, urinary complaints or other symptoms. He had no history of medical disease or congenital anomaly, and the rest of the skin was normal. Biopsy showed a dermal cyst lined by pseudostratified columnar epithelium.

Case 2-A 8-month-old boy presented with linearly arranged, multiple pinhead-sized to rice-sized whitish cysts along the median raphe from the perineum to mid of scrotum (Figure 2-3), which were present from birth and progressively increased in size and number.The lesions spread along the perineal raphe and had a cordlike appearance. The infant showed no signs of pain, tenderness, pruritus, or other symptoms. He had no history of medical disease or congenital anomaly, and the rest of the skin was normal. Ultrasound was performed showing cystic formations with hyperechoic content was documented, without evidence of expansion deeper to the endoscrotal structures. A skin biopsy was performed at the upper cystic portion of the lesion and the biopsy specimen showed the cysts located in the dermis with variable lining. Some parts were lined by stratified squamous epithelium andother parts consisted of cuboidal urothelium-like epithelium with mucinous cells. Thus, a diagnosis of mixed-type median raphe cysts was made.

Median raphe cysts are rare, benign congenital lesions that can develop anywhere along the midline of the ventral side of the male genital area. They can form from the urethral meatus to the anus and the perineum along the perineal raphe. Although present since childhood, they are sometime reported by young adults when they increase in size, get infected or cause sexual discomfort histologically, they are classified into four types. The urethral type, the most common, consists of an urothelium-like epithelium, with a layer of columnar cells overlaid with several stratified layers of uniform small cells. The epidermoid type consists of stratified squamous cell epithelium. The glandular type consists of a well-formed intraepithelial glandular structure in the lining of the urethral epithelium. The mixed type, the second most common and the type of this case, consists of more than one type of epithelium, including the urethral epithelium with squamous metaplasia, urethral epithelium with mucinous cells, or a combination of these three [3].

The pathogenesis is unclear, but several hypotheses have been proposed. First, the 'tissue trapping' theory states that median raphe cysts are caused by either a defective fusion of the urethral folds or an anomalous outgrowth of the epithelium during the development of the urethra [7]. Second, median raphe cysts may result from the anomalous developmental rest of the periurethral glands of Littre. This hypothesis may help explain glandular type median raphe cysts and the involvement of mucinous cells in some cases [8]. A third hypothesis suggests that blockage of the paraurethral ducts may underlie the development of median raphe cysts [9]. MRCs may regress spontaneously. Shibagaki et al. believe that small and asymptomatic MRCs can be observed without excision, because there is the possibility of regression [10]. Therapeutic intervention may be indicated due to secondary infection leading to pain or cosmetic reasons [11]. Optimal treatment of MRCs is surgical excision and primary closure, which prevents infection or cosmetic sequelae [12]. Aspiration alone is not recommended as a treatment option for MRCs. Asymptomatic lesions are left untreated .Complete local excision is recommended for the symptomatic lesions to prevent possible complications. Furthermore, whether associated congenital anomalies are present should also be assessed.

The canaliform median raphe cysts demonstrated in the present cases are an uncommon presentation of this rare condition, and reports of these cysts are rare. Most patients present with a single isolated from or a few cysts. The patient described here presented with multiple, continuous cysts. This unique morphology makes diagnosis confusing due to its rarity and particular clinical features. Thus, histologic confirmation is often required.

Conflict of interest and financial funding–none

Figure 1: Congenital Multiple Whitish Cysts

Figure 2: Canaliform Medial Raphe Cyst

Figure 3: Congenital Multiple Whitish Cysts Extending from Anus to Mid Scrotum

1. Mermet P. et al. "Congenital cysts of the genitoperineal raphe." Revue de Chirurgie, vol. 15, 1895, pp. 382–435.

2. Betül Ü. et al. "Perianal median raphe cyst: a rare lesion with unusual histology and localization." Case Rep Dermatol Med, 2015, Article ID 487814, 3 pages.

3. Shao I.H. et al. "Male median raphe cysts: serial retrospective analysis and histopathological classification." Diagn Pathol, vol. 7, 2012, Article 121.

4. Krauel L. et al. "Median raphe cysts of the perineum in children." Urol., vol. 71, 2008, pp. 830–831.

5. Soendjojo A. and Pindha S. "Trichomonas vaginalis infection of the median raphe of the penis." Sex Transm Dis, vol. 8, 1981, pp. 255–257.

6. Ark C.O. et al. "Median raphe cyst on the scrotum and perineum." J Am Acad Dermatol, vol. 55, no. 5, 2006, pp. 114–115.

7. Nagore E. et al. "Median raphe cysts of the penis: a report of five cases." Pediatr Dermatol, vol. 15, 1998, pp. 191–193.

8. Dini M. et al. "Median raphe cyst of the penis: a report of two cases with immunohistochemical investigation." Am J Dermatopathol, vol. 23, 2001, pp. 320–324.

9. Shiraki I.W. et al. "Parametal cysts of the glans penis: a report of 9 cases." J Urol., vol. 114, 1975, pp. 544–548.

10. Shibagaki N. et al. "Spontaneous regression of congenital multiple median raphe cysts of the raphe scrota." Br J Dermatol, vol. 134, 1996, pp. 376–378.

11. Deliktas H. et al. "Median raphe cyst of the penis." J Urol., vol. 12, no. 4, 2015, pp. 2287–2288.

12. Soyer T. et al. "Scrotal pearl is not always a sign of anorectal malformation: median raphe cyst." Turk J Pediatr, vol. 55, no. 6, 2013, pp. 665–666.