Extra-testicular Intra-scrotal Median Raphe Epidermoid Cyst Mimicking Polyorchidism in a Child

Introduction

Scrotal swellings in pediatric age are rare, but important as they range from totally benign lesions to highly malignant tumors (2). Their mainstay of management is surgical. The type differs according to the site of the cyst. Median raphe swellings are very rare developmental cysts that rarely present in childhood. The median raphe cyst ventral to the penis might prove to be glomus tumor, dermoid cyst, pilonidal cyst, apocrine cystadenoma or hydrocystoma, epidermal inclusion cyst, urethral diverticulum, and steatocystoma.They arise anywhere from urethral meatus to anus, commonly on the ventral surface of the penis close to the glans. They present as a solitary cyst or multiple median raphe cysts (3, 4). These cysts are commonly small, silent and present beyond the age of 10 years. They grow slowly and rarely are complicated by infection as Staphylococcus aureusand Neisseria gonorrhoeae leading to purulent discharge (5). The median raphe cysts presenting in the scrotum might be socially accepted as polyorchidism not warranting medical opinion despite the fact that a third or supernumerary testicle is exceptionally rare (6).

Pre-operative diagnosis is important to avoid un-necessary testicular surgery. We aim to describe our experience with a median raphe cyst in a 6-year-old child who was thought by parents to have a third testicle. They sought medical advice as it underwent recent painless growth.

Case Presentation

A 6-year-old male, with normal developmental milestones, weights 22 kg and height 115 cm presented with painless scrotal swelling in the median raphe that was first noticed by his mother when he was one-year and started to increase slowly in size. The family did not seek medical advice early because they thought this swelling was a third intra-scrotal testis. They sought medical advice as the mass underwent recent painless growth and became quite large. No urinary or other systemic symptoms were reported. The lesion was oval and measured 5x2x1cm (Figure1). It was not tender, not compressible and completely separable from both testes. There were neither skin manifestations nor secondary lymphadenopathy. The patient had no medical history and no family history of similar conditions.

Ultrasound examination revealed a well-defined, 5.3x1.2x2 cm tubular structure at the perineum and homogeneously low echogenic cystic content. No increased vascularity was noted. Both testes were of normal site and size with normal parenchymal vasculature and echogenicity. Both epididymi were normal with no varicocele or hydrocoele.

Magnetic resonance imaging (MRI) elicited low T1 and high T2 signal intensity, which confirmed the presence of an anterior midline uni-locular perineal cyst with slight inclination to the right. (Figure 2). The cyst was thin walled, extending from the root of penis to the perineum. It was seen separable from the urethra and both testes. Clinically, the swelling was located within the scrotum but extending deeper towards root of the penis. Due to the highly suggested benign nature, no tumor markers were tested for.

The swelling was surgically excised as a day-case procedure through a longitudinal midline incision in the perineum. (Figure 3). The cyst was not attached to the skin. No intraoperative complications were encountered. The lesion exhibited a gross picture (Figure 4) of epidermoid cyst filled with grayish pasty material with no gross adnexal structures, as well as a microscopic picture (Figure 4) of stratified squamous lining with secondary ulcerations. Two-year follow-up revealed no evidence of recurrence nor other complications.

Discussion

Extra-testicular scrotal swellings in a child bear a wide range of diagnoses ranging from benign to highly malignant tumors. These lumps should be meticulously assessed to set the appropriate management plan as approximately half of the painless scrotal swellings in children are malignant. The malignant ones usually present as solid masses, cystic swellings are typically benign (2). Even though extra-testicular scrotal swellings are usually para-median, those arising in median raphe from anterior anal end to the tip of penis are less commonly described (7). Previously, median raphe cysts were termed and included mucoid, genitourinary cysts, apocrine cystadenoma, and other terms due to their common embryological defect (4). Later, the cystic ones were described as mucoid or epidermoid cysts  (7).  

The epidermoid cysts are sebaceous cysts that result from plugged pilosebaceous follicle, they are more abundant on head, neck and groin. They do not typically arise as median raphe cysts (8). Moreover, defective closure with ectopic urethral mucosa sequestration or entrapment of ectopic peri-urethral glands of Littre will cause urethral or mucoid cysts. Another proposed theory is the congenital obliteration of para-urethral ducts (4). These cysts are usually small in size with distinctive patterns of being a globular cyst, an elongated raphe canal or multiple cysts (3, 9). MRI and not ultrasonography is of choice for its discrimination (10). Similar lesions are not reported below the age of 10 years except in few reports. (Table 1). Its small size and asymptomatic nature delay early presentation except in adolescence or adulthood, which is the usual age of presentation.

Table 1.  Review of studies of median raphe cysts in children below 10 years

Table 2. Review of studies reporting large median raphe cysts in adults

Unlike our patient, rarely the cyst measures a size more than 2 cm  (5). (Table 2) and the guardians and patients seek advice for aesthetic purposes or uncommonly to manage complications such as infection, trauma, interference with sexual life or urinary complications  (3, 5). Differential diagnosis of such swelling could include polyorchidism as the family assumed at the beginning in our case. It is a very rare condition which is defined by the presence of more than two testes (24). Its presentation is commonly in the form of tri-orchidism, in which an extra testicle is usually found on the left side. The exact etiology of polyorchidism is still unknown (6). Differential diagnoses also include pseudo-tumors, testicular duplication, fetus-in-fetu and hamartoma  (23, 25–27). However, malignant tumors such as rhabdomyosarcoma should be considered (2). Perineal masses are associated with anorectal malformations hence careful examination of perineum is important but in our patient there were no such anomalies (27–30).

Although physical and radiological assessment suggests the cyst type, histopathological confirmation is needed. Four types have been identified: urethral, epidermoid, glandular, and mixed  (5, 19). According to the lining, pseudostratified columnar epithelium, stratified squamous epithelium, urothelium, glandular epithelium and coexisting mixed epithelium, respectively. Other authors added ciliated and pigmented types (4). With the advent of artificial intelligence this kind of differentiation is promised be easier radiologically (31).

Management of the cysts depends on the symptoms and the patient's preference (5). Surgical excision is considered to be the treatment of choice for these patients. Not only does it provide best aesthetic outcomes with minimal rate of recurrence, but also provides radical management for a wide range of possible complications. Watchful management is considered safe if the patient refuses intervention as spontaneous regression has been reported (4, 5). Aspiration and marsupialization of the cyst are not recommended (4).

Conclusion

Although extremely rare, extra-testicular intra-scrotal epidermoid cysts should be considered in the differential diagnosis of intra-scrotal swellings where radiological investigations can aid the diagnosis. To avoid unnecessary testicular surgery, it is important to exclude malignancies and other commoner etiologies before concluding extra-testicular epidermoid cyst as a working diagnosis and in such cases, surgical excision is the recommended management. Routine thorough examination of pediatric patients presenting with perineal lesions to exclude anorectal malformations.

Author Contributions:

A.O.: finalizing the draft, figures and prepare final manuscript. H.T.: substantial contribution to the conception and revisions. M.G.: operating, follow-up of patient, prepare initial draft. B.M.: edit the initial draft and organize the gathered data. A.N. and S.T.: prepare the histopathology section and confirms the rarity of the case as well as provide histopathology figure. M.A. and A.A.: interpretation of data and drafting work as well as reviewing the literature. M.E. and K.A.: suggesting the idea and supervising the work. S.A looking up patient data. M.K revision and editing of manuscript. All authors have revised the literature, approved the submitted version and are accountable for the authors’ contributions.

FUNDING

Authors declare there was no extramural funding provided for this study.

CONFLICT OF INTEREST

The authors declare no conflict of interest. Authors declare veracity of information.