Complex anal fistula involving male genital tract: a new diagnostic entity

Abstract

We present three male patients who had a rare presentation of anal fistula reaching the genital tract. Patient 1: a 44-year-old diabetic man presented initially to urology clinic complaining of penile and scrotal masses increasing in size for 6 months. Patient 2: a 67-year-old diabetic man presented with chronic sinus discharge from the scrotum. Patient 3: a 37-year-old diabetic man who presented with chronic sinus draining pus-like material from the scrotum for 1 year. Patients 1 and 2: following diagnosis of perianal fistula by MRI fistulography, complete excision of the fistula was done. This required tracking the fistula surgically, a perineal midline incision to release the fistula and excision of the fistula opening in the anal canal. The patients were doing well postoperative and no recurrence of fistula at 1-year follow-up. Patient 3: he refused surgical intervention. Penile mass or scrotal discharge has not been reported to be caused by fistula-in-ano.

Background

The rarity of these case presentations could lead to confusion in making the diagnosis, as was the case in the first patient. Having a high index of suspicion for this particular presentation is the only way to reach the diagnosis, particularly that these patients had minimal or no anal symptoms and presented to the urologist office.

Case presentation

First patient

A 44-year-old man presented initially to urology clinic complaining of penile mass increasing in size for the last 6 months. He has a history of anal pain on and off for 4 years. No fever, weight loss or anorexia. Patient denied any history of tuberculosis (TB), Crohn’s disease or acquired immune deficiency diseases. He is diabetic on oral hypoglycaemics, and had erectile dysfunction responding well to 20 mg of tadalafil. Physical examination showed a hard-penile mass adherent to mid corpora and left soft scrotal mass measuring 1×1 cm with bilateral enlarged inguinal lymph nodes.

Laboratory workup including tumour markers (beta human chorionic gonadotropin (BHCG), alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA) and lactate dehydrogenase (LDH)), urine cytology, brucellosis titer and serology test for HIV were all negative. The patient was seen by the gastroenterology service and underwent rectal examination and colonoscopy which were normal. Urine PCR for TB was negative, but purified protein derivative (PPD) test was positive, however the patient was living in an endemic geographic region for TB and received previous BCG vaccination. CT scan of abdomen and pelvis showed diffuse thickening and heterogeneous enhancement of the penis forming an ill-defined mass with irregular borders, it measures about 5.5×5 cm. The mass is predominantly solid with significant surrounding fat stranding and few bilateral enlarged inguinal lymph nodes, the largest measures about 2 cm.

Provisional diagnosis was malignancy versus inflammatory mass. To rule out malignancy, the patient opted first for excisional biopsy of the suspicious penile mass, and histopathology showed only chronic non-specific inflammation and sclerosis. Later on, standard MRI of the abdomen and pelvis revealed diffuse thickening and heterogeneous enhancement extending from the base of the penis (parallel to the urethra) to the lateral left wall of the penis inferior to the corpora cavernosa. It measures about 2×1.3×12 cm in craniocaudal, transverse and anteroposterior, respectively. A cystic-like structure is noted in the scrotum measuring about 1.5×1.5×1.4 cm in craniocaudal, transverse and anteroposterior diameters, respectively. The described findings were in keeping radiologically with abscess starting from the base of the penis parallel to the urethra, this could be arising from urethral diverticulum, but no definite underlying tumour is identified (figure 1A,B).

Figure 1.

(A) Axial plane MRI of first patient. (B) Coronal plane MRI of first patient showing the penoscrotal part of the fistula. (C) Axial plane MRI of first patient showing the penoscrotal part of the fistula.

Decision was made at this point to go for scrotal exploration and mass excision. Cystoscopy during the procedure was normal with no evidence of stricture or diverticulum. Histopathology showed the same findings as in the previous biopsy and confirmed no evidence of neoplastic proliferations. TB culture of mass tissue was also negative. Although a clear TB diagnosis was not made, the patient was started on anti-TB treatment empirically by the infectious disease service. Two months later, the patient was still complaining of purulent discharge from the sinuses arising from wound sites spontaneously and increasingly with defecation.

The patient was referred to colorectal surgery service for consultation and further evaluation. Physical examination showed two sinuses at the left aspect of penis root around 2 o’clock with underlying thickening. Moreover, digital rectal examination by an experienced colorectal surgeon revealed normal tone, palpable cord-like structure at 12 o’clock and extending cephalad. Dedicated MRI anal fistulography was ordered for the patient, which showed unchanged left parapenile abscess communicating with anal canal mucosa at 12 o’clock through a small enhancing intersphincteric tract (figure 1C).

Technique

Examination under anaesthesia confirmed the findings of the fistula described above. External opening of the fistula at the root of the penis was probed and was able to go through the tract into the internal opening at dentate line at 12 o’clock. The operation was done in collaboration between the urological reconstructive surgeon and the colorectal surgeon. Incision in pubic area around external opening of the fistula was made, then dissection of the tract was done. Afterward, another incision was made at the perineum and continuation of the dissection carried out to the region of the sphincter. Third incision was made in the anal verge, dissecting the intersphincteric plane around the fistula tract. By the end, the tract was almost completely excised except for the part near the anal fistula which undergone fistulotomy and curettage by the colorectal surgeon. A Penrose drain was left to drain through perineal and pubic incisions and was removed the next morning. Closure of the incisions was done in layers after good irrigation (figure 2).

Figure 2.

Intraoperative image of first patient.

Second patient

A 67-year-old man presented to urology clinic as a consultation for chronic sinus discharge from the scrotum. He denied any history of bleeding per rectum, weight loss or anorexia. He had previous history of recurrent perianal abscesses treated with incision and drainage. No history of congenital anomalies or previous exposure to radiation. He is known to have diabetes mellitus controlled by oral hypoglycaemics and hypertension. Urologically, he has benign prostatic hyperplasia, Peyronie’s disease, and severe erectile dysfunction not responding to intracavernosal injections. Patient denied any history of TB, Crohn’s disease or acquired immune deficiency diseases. Physical examination showed opening at 6 o’clock position of the anal canal and at the posterior margin of the scrotum with no palpable tract in the perineum. He has mid-shaft penile plaque 2×3 cm and normal testes.

Blood investigations were unremarkable. Colonoscopy showed neither signs of inflammatory bowel disease nor malignancy. MRI fistulography showed a fistula with mucosal opening at 6 o’clock position of the anal canal and branches out in the intersphincteric space. The first branch tracks inferiorly to drain at the perianal region. The second branch tracks clockwise to 12 o’clock position, then it crosses the external sphincter anteriorly. The tract after that branches out into two tracts coursing along the sides of the penis base, the right-side tract is seen extending anteriorly and terminates in the midline of the scrotum (figure 3).

Figure 3.

MRI of second patient.

Technique

Examination under anaesthesia showed external opening in the scrotum and coursing near the left inferior aspect of the root of the penis (figure 4). Probing of the tract was done and it was found to be directed to deep tissues and could not be manoeuvred to reach the tract described above. Dissection of intersphincteric plane at 6 o’clock was done followed by ligation of anal part of the tract was done. Fistulectomy of the distal scrotal part of the fistula was then done and required a perineal incision to assist in dissection. The fistula was very adherent to the corpus spongiosum in the proximal bulbar urethral region and fistulotomy with curettage was done for the very proximal part of the fistula. Penrose drain was kept for 1 day. Closure of the incision was done in layers after good irrigation.

Figure 4.

Intraoperative image of second patient.

Third patient

A 37-year-old man who presented the urology clinic with chronic sinus draining pus-like material from the scrotum for 1 year. He had no rectal pain or discharge. No history of perianal fistula or abscess. His history was only significant for diabetes mellitus and he is on oral hypoglycaemic agents. Patient denied any history of TB, Crohn’s disease or acquired immune deficiency diseases. Physical examination showed opening at 1 o’clock position of the anal canal and at the posterior margin of the scrotum with no palpable tract in the perineum.

Blood investigations were unremarkable. MRI fistulography showed a fistula with mucosal opening at 1 o’clock position of the anal canal and branches out in the intersphincteric space. The tract passes anteriorly to open on the right side of the back of the scrotum (figure 5). This patient refused any sort of surgical intervention or procedure.

Figure 5.

MRI of third patient.

Outcome and follow-up

First patient

Postoperative period was uneventful. Histopathology came in consistence with anal fistula as showing chronic non-specific inflammation and no malignancy was identified. One-month follow-up showed good healing of the wounds. At 1-year follow-up, the patient had no complaints. No voiding symptoms, no anal complaints and no more discharge. The patient experienced transient worsening of erectile function postoperatively. This has returned to baseline 6 months after surgery.

Second patient

Postoperative period was uneventful. Two-month follow-up showed good healing of surgical wounds and complete resolution of the fistula with no more symptoms. Histopathology showed chronic non-specific inflammation and no malignancy was identified. Penile prosthesis insertion was advised for his erectile dysfunction, but the patient decided to wait on that procedure.

Third patient

This patient refused any sort of surgical intervention or procedure and was lost to follow-up.

Discussion

The above three cases have very unusual presentation of fistula-in-ano reaching the male genital tract. Establishing diagnosis in such complex cases with bizarre involvement of male genital tract requires detailed history and thorough physical examination. A history of perianal abscess drainage might help not to overlook hidden anal fistula. All the three patients share diabetes mellitus as an associated diagnosis. Diabetes mellitus is known to increase the risk of anal fistula.¹ Infectious diseases such as TB are risk factors that should be kept in mind in the differential diagnosis, especially in endemic areas. Examination of the perineum may reveal external opening, scar, palpable tract or perineal body deformity. Digital rectal examination might help to locate the internal opening and to check the anal sphincter tone. Only dimpling or area of irregularity can be felt, especially in high-anal fistula in which the internal opening might not be visible. Examination under anaesthesia could be more comfortable for the patient and the physician to assess the fistula by using different tools including tract probing, methylene blue dye injection or hydrogen peroxide to delineate the internal opening and flexible sigmoidoscopy. Full colonoscopy might be essential to screen for inflammatory bowel disease or malignancy. MRI is of the essence in managing such complex fistulas. It will help to assess the anatomy and adjacent structures, identifying branching tracts or collections and to outline the relationship of the fistula to anal sphincter.² MRI is considered the best imaging modality for anal fistula assessment, prognosis prediction and treatment monitoring. It provides the highest sensitivity of 97% of all modalities, and can be done in the preoperative period for surgical planning.^{3 4} The fistulas in these patients were only demonstrated using MRI with perianal fistula protocol. Therefore, keeping a high index of suspicion of this presentation is essential in order to request this particular study. MRI was performed using a 1.5 tesla scanner (Siemens). The protocol used at our institution for evaluation of perianal fistulas consists of the following sequences: quick localiser images, transverse diffusion-weighted echo planar two-dimensional (EP2D), transverse turbo spin-echo with T1-weighted, sagittal turbo inversion recovery magnitude with T2-weighted, sagittal/transverse fat-suppressed (FS) T2-weighted BLADE, sagittal/coronal/transverse isointense volumetric interpolated breath-hold sequence with T1-weighted FS with gadolinium-based contrast material. MRI images were evaluated by a specialised radiologist with experience in reading pelvic MRI. Management goals for complex anal fistulas are to cure disease, prevent recurrence, preserve anal sphincter integrity and limit morbidity of surgical intervention. Local control of sepsis and abscess drainage should be done initially before any attempt for definitive treatment. Options include setons, fistulotomy or fistulectomy, endorectal advancement flap, fistula plug, fibrin glue, electrocauterisation of tract and ligation of intersphincteric fistula tract.^{2 5} We cannot conclude on the success of these options in the management of this particular presentation, however they can be discussed with the patient. Reduction in quality of life of patients with anal fistula is undeniable and is worse in patients with recurrent disease and secondary extensions.⁶

It is worth mentioning that it has been documented in the literature that Crohn's disease can present with complication of scrotal abscess due to anal fistula.⁷ Furthermore, Yang et al reported a case of imperforate anus with rectopenile fistula and systemically reviewed the literature for similar eight cases with different anorectal malformation in paediatric age group.⁸ On the other hand, Troja et al reported one case of idiopathic anal fistula extended to the female genital tract as rectovaginal fistula.⁹

Involvement of male genital tract in anal fistula might lead to a diagnostic hassle, aggressive intervention and reconstructive challenge. The first case of penile swelling has driven our thoughts to rule out malignancy initially but diagnosis of penile chronic inflammatory mass due to fistula in-ano was made eventually. Penile abscess has been described in the literature to be precipitated by penile trauma, after intracavernosal injection and disseminated infections, but not to be a consequence of anal fistula. Surgical drainage mostly warranted to treat underlying causative fistula and reduce risk of recurrence. The most frequent complication of surgically treated penile abscess is penile curvature without necessarily affecting erectile function.¹⁰

Learning points.

• Due to rarity of anal fistula extension into male genital tract and its variable presentations, the urologist should have a high index of suspicion and consider anal fistula disease in the differential diagnosis of patients presenting with penile swelling and scrotal discharge.

• History of diabetes mellitus should increase the suspicion of the disease. If this disease is suspected, then requesting MRI with perianal fistula protocol should be considered.

• Fistulectomy is a safe and successful surgical option in treating the disease with this presentation.