The perineum is a diamond‐shaped region that lies below the pevic floor. A transverse imaginary line drawn between the ischial tuberosities divides th...
A 4‐month‐old female child with a perianal infantile haemangioma.
Perianal and natal cleft psoriasis causing fissures in a 42‐year‐old woman.
Hailey–Hailey disease affecting the ano genital region and causing inflammation and superficial blistering. A skin biopsy has been taken for histology...
Furunculosis affecting the buttocks of a 22‐year‐old female.
Florid perianal warts in a 5‐year‐old male.
Squamous cell carcinoma infiltrating adipose tissue that has developed from adjacent high‐grade anal intraepithelial neoplasia. Magnification 400×. (...
(a) Infiltrative carcinoma erysipeloides affecting the genito‐crural region and lower abdomen in a man with adenocarcinoma of the colon. A colostomy b...
(a) Pilonidal sinuses in a natal cleft with buttock abscesses. (b) Close‐ up view of the same pilonidal sinus.
Cryptoglandular hypothesis of the development of an intersphincteric fistula.
Second degree prolapsed internal haemorrhoids with surrounding anal tags. (Courtesy of Mr M. Abulafi, Croydon University Hospital, UK.)
Coronal section through the anal canal. (From Standring 2008 [ ].)
Excoriations secondary to idiopathic pruritus ani in a 6‐year‐old boy. It is important to exclude threadworms at this age.
Contact dermatitis causing blistering in an infant due to the use of wet wipes.
Perianal contact dermatitis caused by imiquimod cream used to treat perianal warts.
Ulcerated and inflamed skin affecting the natal cleft and buttock secondary to herpes simplex type II virus infection.
Histopathology of low‐grade anal intraepithelial neoplasia. Koilocytes are present high in the upper half of the epidermis. Magnification 200×. (Cour...
(a) Large polypoid mass of perianal carcinoma in a 56‐year‐old female. (b) Close‐up view of the same carcinoma.
Hurley stage I hidradenitis suppurativa presenting as chronic furunculosis on the buttocks.
MRI scan of the patient with sacrococcygeal pilondal disease shown in Figure A sagittal T 2 ‐weighted small field of view image showing multiple sin...
Parks classification of anal fistulae. A: superficial fistula track beneath the internal and external sphincters. B: intersphincteric fistula track be...
Perianal skin tag.
Muscles of the pelvic floor in a female. The levator ani muscle complex is composed of the ischiococcygeus, iliococcygeus and pubococcygeus muscles. T...
Vegetative pemphigus foliaceous. (a) Affecting the genito‐crural region and lower abdomen. (b) Affecting the perianal region and buttocks in the same ...
Lichen sclerosus. (a) Ano‐genital lichen sclerosus in a female in a typical figure‐of‐eight configuration. (b) Perianal lichen sclerosus.
Perianal ulceration due to nicorandil. (Courtesy of Dr S. Baron and Dr E. Kulakov, Kent, UK.)
Condylomata lata. (Courtesy of Dr S. Gold, London.)
Histopathology of high‐grade anal intraepithelial neoplasia (AIN). (a) High‐grade, full‐thickness AIN. Magnification 100×. (b) High‐grade AIN occurrin...
Poorly differentiated, eroded, perianal nodule of squamous cell carcinoma present at the anal margin occurring in a 50‐year‐old HIV‐negative man withi...
Hurley stage II hidradenitis suppurativa. (a) Affecting the groin of a female causing sinus track formation and scarring. (b) Affecting the axilla of ...
Crohn disease: perianal and buttock involvement. (Courtesy of Dr D. I. McCallum, Inverness, UK.)
Typical positions of development of internal haemorrhoids in the anal canal at 3, 7 and 11 o'clock seen with the patient in the dorsal lithotomy posit...
Obstetric perineal trauma. (a) Cloacal‐like defect following a missed third degree tear. The perineal body is absent and there is minimal tissue separ...
Partitioning of the cloacal membrane into the uro‐genital membrane and anal membrane with the formation of the perineum occurs at 5–7 weeks’ gestation...
Seborrhoeic dermatitis affecting the natal cleft and perianal skin.
Perianal lichen planus showing Wickham's striae. (Courtesy of Dr F. Ive, Durham, UK.)
Panton–Valentine leukocidin Staphylococcus aureus infection affecting the buttock of a 3‐year‐old female.
Perianal wart. (a) Low power histological features of a perianal wart showing hyperkeratosis, acanthosis and papillomatosis. Magnification 40×. (b) Hi...
Eroded patch of perianal high‐grade intra‐epithelial neoplasia (Bowen disease) in a 75‐year‐old female.
Buschke–Löwenstein tumour affecting the perianal skin of a 56‐year‐old male.
Hurley stage III severe hidradenitis suppurativa. (a) Affecting the perineum and causing extensive keloid scar formation in a 75‐year‐old male patient...
Classification of ano‐rectal abscesses based on the relation of the abscess to the internal and external anal sphincters.
Origin of internal and external haemorrhoids. (Adapted from Snell 2012 [ ]. Reproduced with permission of Lippincott Williams & Wilkins/Wolters Kluwe...