We present the case of monochronic dizygotic twins with perianal abscesses coincident in chronology and morphology. This image typifies the features of infant perianal disease that suggest a congenital aetiology.
Twin 1 (weight 3.67 kg) and Twin 2 (weight 3.91 kg) were admitted to a tertiary paediatric surgical unit on the 34th day of life following a history of perianal abscess at the 11- and 10- o'clock positions, respectively (figure 1). This photograph was taken on the 35th day of life. Prior to referral, both patients received oral, then intravenous co-amoxiclav with little local improvement. Incision and drainage was carried out on the 39th (Twin 1) and 35th (Twin 2) day of life, respectively. Escherichia coli (Twin 1) and E Coli and Staphylococcus aureus (Twin 2) were cultured from the abscess pus.
Perianal abscesses are found within 2 cm of the anal verge and are relatively common in infants (estimated incidence 0.5–4.3%). Features suggestive of congenital aetiology are as follows:
- Majority occur within the first year of life.1
- There is a male preponderance. Fitzgerald et al2 speculate that an excess of androgen acting on anal glands in utero results in the formation of abnormal glands.
- Abnormal crypts of Morgagni entrap bacteria leading to abscess formation. Normal crypts are usually shallow (1–2 mm). Shafer et al3 observed an association between perianal abscess formation and an irregular dentate line with deeper crypts (8 mm) and posited a developmental anomaly during fusion of the dorsal cloacal membrane with the hindgut.