Differential Diagnosis for Anal Pruritus
The patient's symptoms of anal pruritus worsening at night or with constipation, along with a past medical history of hemorrhoids, guide the differential diagnosis.
Single Most Likely Diagnosis
- Hemorrhoids: Given the patient's past medical history of hemorrhoids, this condition is a likely cause of anal pruritus, especially if the hemorrhoids are thrombosed or prolapsed. Constipation can exacerbate hemorrhoid symptoms, and nighttime worsening could be due to increased venous pressure in the recumbent position.
Other Likely Diagnoses
- Anal fissure: This condition can cause severe pain and itching, especially with constipation, as hard stools can further irritate the fissure.
- Fecal incontinence or leakage: Even minor leakage can cause irritation and itching around the anus, worsened by constipation due to the harder stool consistency.
- Pruritus ani (idiopathic): A condition characterized by intense itching around the anus without an identifiable cause, which can be exacerbated by various factors including constipation.
Do Not Miss Diagnoses
- Inflammatory bowel disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause anal pruritus among other symptoms. Missing this diagnosis could lead to delayed treatment and significant morbidity.
- Anal or rectal cancer: Although rare, these cancers can present with anal pruritus, among other symptoms like bleeding or changes in bowel habits. Early detection is crucial for treatment outcomes.
- Infections (e.g., candidiasis, herpes simplex): Certain infections can cause anal itching and are important to diagnose due to the availability of effective treatments.
Rare Diagnoses
- Lichen sclerosis: A rare skin condition that can cause itching and skin changes in the anal area.
- Psoriasis or other dermatological conditions: While more commonly associated with skin lesions elsewhere on the body, these conditions can occasionally cause anal pruritus.
- Neurological disorders (e.g., neuropathy): In some cases, neurological conditions can lead to anal pruritus, though this would be an uncommon presentation.