What are the differential diagnoses for perianal abscess?

　　Differential diagnoses of perianal abscess include anal fistula, perianal folliculitis, infected sebaceous cyst, pilonidal sinus, and anorectal tumors. Differentiation should be made based on symptoms, physical signs, and examinations to avoid misdiagnosis and delayed treatment. If symptoms such as redness, swelling, heat, pain around the anus, or fever occur, prompt medical evaluation is recommended for accurate diagnosis.

　　1. Anal fistula: Most anal fistulas have a history of perianal abscess. They present with a chronic external opening that repeatedly discharges pus; squeezing reveals exudate. There is no obvious acute redness, swelling, heat, or severe pain. In contrast, perianal abscess is an acute infection characterized by intense pain and fever.

　　2. Perianal folliculitis: This condition is localized to hair follicles, with small areas of redness and swelling, often accompanied by a white pustule. Pain is mild, and there is no deep tenderness. Perianal abscess, however, presents with extensive redness and swelling, severe pain, and deep tenderness.

　　3. Infected perianal sebaceous cyst: This results from secondary infection of a pre-existing sebaceous cyst. Before infection, a subcutaneous round mass can be palpated. After infection, it becomes red, swollen, and painful. In contrast, perianal abscess does not have a preceding mass and presents acutely with inflammatory symptoms from onset.

　　4. Pilonidal sinus: Commonly occurs in the sacrococcygeal region, presenting with recurrent episodes of redness, swelling, and pain. A firm subcutaneous nodule may be palpable, and hair may be found in the pus. Perianal abscess typically occurs around the anus and does not discharge hair.

　　5. Anorectal tumors: When complicated by infection, these may present with redness, swelling, and pain, but are often accompanied by changes in bowel habits, rectal bleeding, and a hard mass on palpation. In contrast, perianal abscess is an acute infectious lesion, usually soft with fluctuation.

　　Daily care includes maintaining cleanliness and dryness of the perianal area, wearing loose and breathable clothing, and avoiding prolonged sitting. Diet should exclude spicy and irritating foods; increased intake of fruits and vegetables helps maintain regular bowel movements. Do not squeeze perianal lumps manually to prevent spreading infection.