李明儒¹²、王巽玄¹²、李永進¹²

¹高雄市立小港醫院 泌尿部；²高雄醫學大學附設醫院 泌尿部

Ming Ru Lee¹², Hsun Shaun Wang¹², Yung Chin Lee¹²

¹Department of Urology, Kaohsiung Municipal Siaogang Hospital, Kaohsiung, Taiwan；

²Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung Medical University,

Kaohsiung, Taiwan,

 

Background: Median rephe cysts are rare congenital anomalies presented as the cysts at the midline of the male external genitalia, including penile glans, shaft and scrotum, mostly less than 1 cm. We report a rare case with 4 cm reproductive median raphe cyst at the midline scrotal perineal region. The objective of the case presentation is to provide the review of the rare median rephe cyst in the clinical characteristic, differential diagnosis, pathogenesis, histological features and treatment.

Case presentation: A 49-year-old man presented to our outpatient department with persistent perineal mass with intermittent pain for years. The mass was elastic, smooth, non-movable and over the midline of the scrotal perineal region. Ultrasonography showed homogenous fluid lesion at the region. Computed tomography revealed cystic lesion abutting the scrotum and deep perineum. Perineal cyst aspiration was arranged and fluid analysis revealed 25 ml aseptic fluid contained with inflammatory and degenerated cells. The cyst recurred weeks after the aspiration. Magnetic resonance imaging revealed scrotal perineal cyst without obvious communication with anus or urethra. Surgical excision confirmed well defined cyst lesion without fistula to the adjacent organs. Histopathology showed the cyst lining with squamous epithelium and inflammatory cell infiltration. Differential diagnosis included median raphe cyst, spermatocele, epidermoid cyst, urethra diverticula, anal fistula, abscess and apocrine cystadenoma. Combined with clinical and histological features, median raphe cyst was diagnosed.  

Conclusion: Median raphe cyst is an embryological defect with challenging diagnosis. The cyst is generally believed to result from anomalous of the genitourethral folds and urethral plate. The formation is most often noticed anywhere in the midline from glans to anus. Neither the urethra nor the rectum  communicates with the median raphe cyst. Histologically, the cyst lining is variable and usually consists of pseudostratified columnar epithelium or stratified squamous epithelium. Although past reviews show cystic lesion often range less than 1 cm and present at penile shaft or glans, we report a case of 4cm reproductive median raphe cyst at a patient`s scrotum. The diagnosis is clinical with histological confirmation. We believe it is important for clinicians not only to recognize the median raphe cyst, but also to differential diagnosis with other lesion. With the minimal chance of recurrence, surgical removal is indicated.