Approach to perianal problems: Clinical sciences

Perianal diseases are conditions that affect the anus and the surrounding skin. They are common and usually benign, but sometimes they might be malignant. For the majority of perianal diseases, there are 4 main clinical features that can help you narrow down your differential diagnoses. They include pain, palpable mass, bleeding, and drainage. For example, painless or minimally painful conditions include fistulas, carcinomas, warts, prolapses, and hemorrhoids. On the other hand, painful perianal diseases include thrombosed hemorrhoids, abscesses, anal fissures, and pruritus ani.

When assessing a patient with a chief concern suggesting perianal disease, your first step is to obtain a focused history and physical examination, including a digital rectal exam. Start by evaluating for perianal pain. If the patient reports no pain, your next step is to assess for a mass. If there is no palpable mass too, you should be thinking about a fistula.

Now, even though the patient might deny pain at the time of evaluation, they might report a history of mild cyclical discomfort and swelling around the perianal region in addition to noticing some foul-smelling or bloody drainage. Sometimes they might have risk factors like Crohn disease or previous episodes of a perianal abscess.

On physical exam, you’ll usually see an external skin opening that looks like a large pore. Additionally, there might be erythema and inflammation around the opening. Keep in mind that some patients might have multiple external openings, especially those with Crohn disease. On palpation, you might even feel a superficial cord-like structure under the skin. If you see these findings, consider perianal fistula. Next, perform an anoscopy to look for an internal opening of the fistula tract. If anoscopy is not able to provide adequate visualization or the patient is unable to tolerate the exam, you can perform an exam under anesthesia, or EUA. Once you see the internal opening of the fistula, you can confirm the diagnosis of perianal fistula.

Here's a clinical pearl! There are 4 types of perianal fistulas. They can be intersphincteric, trans-sphincteric, supra-sphincteric, and extrasphincteric. Sometimes a pelvic MRI can be obtained to better identify the fistula tract and its anatomical course if anoscopy or EUA is unclear.

Alright, now let’s talk about the painless conditions with a mass. Of these, the most serious one is anal carcinoma. History typically reveals itching and bleeding around the perianal region, as well as unintended weight loss and a history of HPV or HIV infection. On physical exam, you can expect to find an irregular, friable, or firm mass, possibly with ulcerations and some bleeding. You might also see an induration of soft tissues around the perineal area. In this case, you should consider anal malignancy. Next, perform an anoscopy which might show a polypoid, ulcerated, or cauliflower-like mass within the anus. Then, biopsy the lesion. If it reveals malignant cells, most commonly squamous carcinoma or adenocarcinoma, that’s anal carcinoma.

Okay, let’s move on to benign conditions, starting with anal warts or condyloma, and polyps. The patient will usually report wart-like lesions in the perianal area. Although the majority of warts and polyps are asymptomatic, they could cause some itching and bleeding. These are often caused by HPV or HIV infections. So, history might reveal several risk factors such as unprotected anal sex and multiple sexual partners. If on physical examination, you find a soft lump that is yellow or pink in color, consider a perianal wart or a polyp which are both benign lesions. Your next step is to test for current HPV and HIV infection and obtain a tissue biopsy. Sometimes, HPV or HIV tests will come back positive, but the biopsy will show a benign verrucous, exophytic mass confirming the anal wart, condyloma, or polyp.

Here's a high-yield fact! There are over a hundred different types of HPV, however, four of them are known to cause perianal and genital warts. Benign condyloma acuminata is caused by serotypes 6 and 11, while dysplastic and malignant warts are caused by serotypes 16 and 18.

Next up, let’s discuss rectal prolapse. On history, patients often report chronic constipation with prolonged straining, and sometimes tenesmus. If on physical exam you see a protrusion of soft rectal mucosa that is reducible but worsens on Valsalva and possibly decreased anal tone on digital rectal exam, you can make your diagnosis of rectal prolapse.

Here's a couple of clinical pearls! A rectal prolapse that is overly edematous and cannot be reduced is an incarcerated rectal prolapse. If left untreated, it can lead to necrosis of the entire rectum which is a surgical emergency.