What is the most likely diagnosis for a patient presenting with perianal pruritus (itching around the anus) at night, without soiling of clothes, and no history of bleeding, pain, or fever?

Most Likely Diagnosis: Internal Hemorrhoids (Answer B)

Based on the clinical presentation of isolated nocturnal perianal pruritus without bleeding, pain, fever, or soiling, internal hemorrhoids are the most likely diagnosis. This presentation is characteristic of early-stage (first or second-degree) internal hemorrhoids that cause itching through mucus discharge and minor irritation, without the complications that would produce other symptoms 1.

Clinical Reasoning

Why Internal Hemorrhoids Fit Best

• Prolapsing hemorrhoids are a recognized cause of perianal itching through mucus discharge and soiling, even when frank soiling of clothes is not apparent 1
• First-degree internal hemorrhoids can cause symptoms (including itching) without bleeding or prolapse 1
• The nocturnal pattern is consistent with minor mucus production that accumulates during recumbency 1
• The absence of pain, bleeding, and fever effectively rules out complications like thrombosis, strangulation, or infection 1

Why Other Options Are Less Likely

Anal Fissure (Option A):

• The cardinal symptom of anal fissure is postdefecatory pain, which this patient explicitly does not have 1
• Fissures typically cause minor rectal bleeding, which is absent here 1
• Itching alone without pain is inconsistent with fissure pathophysiology 1

Perianal Fistula (Option C):

• Fistulas arise from preexisting anorectal abscesses in approximately one-third of cases 2
• Patients would typically have a history of prior abscess, drainage, or palpable cord-like structure 2
• The absence of any history of infection, swelling, or fever makes fistula highly unlikely 2
• Fistulas are associated with discharge and soiling more prominent than simple itching 1

Proctalgia Fugax (Option D):

• This condition presents as sudden, severe, fleeting rectal pain lasting seconds to minutes 1
• Itching is not a feature of proctalgia fugax 1
• This diagnosis is completely inconsistent with the presenting symptom 1

Important Clinical Pearls

Diagnostic Approach

• Physicians should not assume hemorrhoids without proper examination, as "prolapsing hemorrhoids may cause anal itching, but itching is just as likely to be due to inadequate hygiene, minor incontinence, or perianal dermatitis" 1
• A careful anorectal evaluation including anoscopy is warranted to confirm the diagnosis and exclude other pathology 1
• Digital rectal examination and external inspection can identify thrombosed hemorrhoids, skin tags, or other conditions 1

Secondary Causes to Consider

While internal hemorrhoids are most likely, pruritus ani has multiple potential etiologies including 3, 4:

• Inadequate or excessive hygiene 1, 5
• Minor fecal incontinence 1
• Perianal dermatitis 1
• Food irritants 4
• In children specifically, pinworm infection should be considered 5

Management Implications

• If hemorrhoids are confirmed, conservative management with fiber supplementation and avoidance of straining is first-line 1
• For persistent pruritus, proper perianal hygiene, elimination of irritants, and skin protection form the treatment triad 3
• Topical therapies including short-course hydrocortisone or capsaicin may be effective 3, 5
• Complete colonic evaluation is indicated if bleeding develops or if the patient has risk factors for neoplasia 1