A rare cause of acute urinary retention in a young man: A median raphe penile cyst

Abstract

Background:

A penile median raphe cyst is an uncommon congenital lesion that is formed due to failure of the median raphe to close completely during embryo development. The majority of the cysts are asymptomatic and often go unnoticed. Here, we report acute urinary retention as a very rare complication of a penile median raphe cyst.

Case presentation

A 21-year-old single man presented with a sudden onset of acute urinary retention of one days’ duration. Urethral catheterization was done at the Emergency Department and this drained 800 ml of urine. On further questioning, he claimed that he had had a painless nodule at the glans penis since childhood. The swelling increased in size in the past week causing discomfort. He denied any history of genitalia trauma or recent sexual intercourse. On examination, there was a bluish lesion over the ventral aspect of the glans penis measuring about 3 x 2 cm. The lesion was later excised and histopathology revealed a median raphe cyst of the penis.

Conclusion:

A penile median raphe cyst is a rare lesion. Acute urinary retention caused by this lesion is very rare.

Introduction

Congenital lesions in the genitalia area commonly present during early childhood. However, some can manifest later in adulthood and pose a diagnostic challenge to the clinician. Congenital median raphe cysts are relatively rare and are often ignored by the patient until they become complicated.

A median raphe cyst often presents as a small yellowish solitary papule lesion.¹ Thus, it almost always goes unnoticed. At the time of presentation, this lesion commonly has some form of complications such as pain, increase in size, change in color, or difficulty in passing urine.^1–2 Rapid increase in size will obliterate the urethral lumen and may cause difficulty in urination. It is very rare for this lesion to cause the complete closure of the urethral canal that leads to acute urinary retention.

Case presentation

A 21-year-old single man presented with acute urinary retention of one days’ duration. The onset was sudden when he awoke in the morning. Urethral catheterization was performed in the Emergency Department and this drained 800 ml of urine.

On further questioning, he claimed that he had had a painless lesion at the glans penis since childhood. The swelling increased in size in the past week causing discomfort. It was tolerable, and therefore he did not seek any medical treatment. He denied any other urinary symptoms or urethral discharge. He also denied any history of genital trauma or recent sexual intercourse.

On examination, we noted a small lesion over the ventral aspect of the glans penis, measuring about 3 x 2 cm in size (Figure 1A). It was well-circumscribed, bluish in color, but no punctum or signs of inflammation were seen. It was tender on palpation. Before the excision of the lesion, we removed the urethral catheter and re-examined the lesion. Without the catheter in situ, we noted that the urethral opening was completely obscured (Figure 1B). Thus, we postulated that he had developed urinary retention secondary to this lesion at the glans penis.

Figure 1A. A well-circumscribed small lesion over the ventral aspect of the glans penis, bluish in color, no signs of inflammation.

Figure 1B. The urethral opening was completely obscured by the lesion at the glans penis.

Our initial diagnosis was penile hemangioma complicated with thrombosis or intralesional rupture. Intraoperatively, we noted that the lesion was well-circumscribed and enclosed within a thin layer of capsule (Figure 1C). The urethral mucosa was not involved. We proceeded with excision of the lesion followed by meatoplasty. The postoperative period was uneventful and the urethral catheter was able to be removed on Day 3 after the operation. The histopathology result revealed a median raphe cyst of the penis with hemorrhagic features within the lesion (most likely caused by recent bleeding). During his first follow-up 6 weeks after the operation, uroflowmetry showed very good results with a peak flow of 30 ml/s and no significant residual urine in the urinary bladder.

Figure 1C. The excised lesion was well-circumscribed and enclosed within a thin layer of capsule (black arrow). Meatoplasty was done after the lesion was removed (white arrow).

Discussion

A median raphe cyst is an uncommon embryogenic developmental defect of the male genitalia. It was first described by Mermet in 1895.¹ It is also known by several other names, including parameatal cyst, mucous cyst of the penis, and apocrine cystadenoma of the penile shaft.¹ It can be found anywhere from the urethral meatus to the perineum and varies in size. The pathogenesis is postulated to be related to the fusion of the genitoperineal raphe at the midline. Therefore, the cyst development can be anywhere from the penis shaft to the perineum, with the most common site being at the penile shaft.^2–4

The largest series of median raphe cysts were reported by Nishida et al.⁵ They reviewed 225 case reports from 1913 to 2010 and found that 83% of the cysts were solitary.⁵ There were six cases reported as pigmented median raphe cysts forming bluish discoloration of the lesion.⁵ The pigmented cysts were confirmed by the presence of melanin pigments in the histopathology analysis.⁵ In our case, the change in color was not caused by the presence of melanin pigment. Instead, the presence of hemorrhagic features in histology findings suggested that minor trauma could have caused the change in its color.

Median raphe cysts typically present as yellowish smooth papules that usually go unnoticed until trauma or infection occurs, giving rise to pain especially during erection or intercourse.^1–4 In this case, the nodule mimicked a hemangioma, possibly due to the presence of intracystic hemorrhage. Yoshimoto et al.⁶ described a case of a blue-purple median raphe cyst of the penis that closely resembled our case, which was explained by the possibility of hemorrhage within the cyst. This patient had also received an initial diagnosis of hemangioma.⁶ However, a difference is that a history of zipper trauma occurring several years previously was apparent in the report by Yoshimoto et al.⁶ but not elicited in our case. We postulated that early morning erection possibly induced hemorrhagic changes in our case, as he denied a recent history of genitalia trauma or sexual intercourse.

The majority of penile median raphe cysts are asymptomatic and observation alone would suffice. However, with acute urinary retention as described above, intervention is needed to ease the symptoms. In this age group, the common causes of acute urinary retention include urethral stricture, urethral stone, and urethral trauma.⁷ The mainstay of treatment for a median raphe cyst is surgical excision. However, there is a variant of the condition which presents as elongated tracts known as canals. In this condition, videodermatoscopy is used in diagnosis. With a cystic lesion, simple removal would be sufficient, whereas the canal type needs to be excised fully to prevent a recurrence.⁴ To date, the best treatment option is surgical excision of the cyst as it gives the best cosmetic and functional outcome.²