Anal pathology and sexually transmitted diseases

Dr John Schofield Consultant Pathologist, Kent and Medway

This presentation highlights the pathology of anorectal STIs and related tumours that coloproctologists are likely to encounter in routine practice and which may cause diagnostic difficulties; such patients may be referred with a suspected diagnosis of haemorrhoids, anal fissure or inflammatory bowel disease. Anal and rectal pathology in patients with HIV infection and AIDS includes a number of rare infections and tumours related to immunosuppression.

Common clinical presentations of anorectal STIs fall into three groups: inflammatory presentation (e.g. proctitis); ulcerative presentation (anal, perianal or rectal ulcer); and anal warts and tumours. Biopsy shows characteristic features in some but not all of these conditions; early biopsy should be considered in all cases to ensure that an accurate and timely diagnosis is made.

Conditions with an inflammatory presentation include infections due to Neisseria gonorrheae and Chlamydia trachomatis, so-called non-specific proctitis, cytomegalovirus (CMV) proctitis, and lymphogranuloma venereum.

Conditions with and ulcerative presentation include Herpes simplex virus (HSV) infection, syphilis (primary or secondary), idiopathic ulcer in HIV infected patients, chancroid, granuloma inguinale, CMV, histoplasmosis, mycobacterial infection and amoebiasis.

Conditions presenting as warts or tumours include viral warts (related to HPV serotypes 6 and 11), dysplasia and squamous cell carcinoma (related to oncogenic HPV serotypes 16, 18, 31, 35 and 45). The integration of viral oncogenes E6 and E7 is required for the initiation and maintenance of the dysplasia/carcinoma sequence. Dysplasia has been noted in 10% of anal warts in HIV-infected patients but may also be seen in the absence of warty change. Early anal squamous carcinoma may be difficult to diagnose; biopsy for histology is advised to confirm the diagnosis. Non-Hodgkins lymphoma (EBV-related) has been reported in the anal region in several patients with HIV but is rare in the general population. Lymphoma may present as an obvious tumour mass, an ulcer or may stimulate a perianal abscess. Histological features are usually those of diffuse large B cell lymphoma or Burkitt’s lymphoma. Kaposi’s sarcoma may be seen in the anorectal area, usually as part of wider cutaneous and/or visceral involvement. Early lesions are particularly difficult to diagnose on biopsy.

Conclusions

Anorectal manifestations of STIs are not unusual but are variable in presentation, frequently simulating other common conditions. Often patients do not volunteer the relevant sexual history and this should be specifically sought. Management of the sexual partners and the detection of asymptomatic disease are important. Certain patterns of anal STIs suggest acquired immunodeficiency and may be the first presenting feature of AIDS. In patients with HIV and AIDS multiple pathology is common and care must be taken not to overlook a second or even third diagnosis. Routine special staining of biopsy material may help, and immunohistochemistry may be useful for confirmation of viral and other infections.

In cases of anorectal disease in which there is diagnostic difficulty, viral and other cultures and biopsy for histopathology should be considered at an early stage. In particular, chronic HSV infection can be easily missed if not considered in the differential diagnosis. Close collaboration between coloproctologist, genitourinary medicine physicians, histopathologists and microbiologists is required to ensure prompt recognition and treatment of these important anorectal conditions.

References

Shepherd NA. Anal intraepithelial neoplasia and other neoplastic precursor lesions of the anal canal and perianal region. Gastroenterol Clin North Am 2007; 36:969-87

Hagensee ME, Leigh JC, Clark RL. Human papillomavirus infection and disease in HIV infected individuals. Am J Med Sci 2004; 328:56-63

Schofield JB, Winceslaus SJ. Anorectal manifestations of sexually transmitted infections. Colorectal Dis 2001; 3:74-81

Wishner JD, Gottesman L. Sexually transmitted disease in colorectal surgery. In: Surgery of the anus, rectum and colon. 2nd edition (1999) (ed Keighley MRB, Williams NS). WB Saunders, London

Brar HS, Gottesman L, Surawicz C. Anorectal pathology in AIDS. Gastrointest Endosc Clin N Am 1998;8:913-931

Barrett WL, Callaghan TD, Orkin BA. Perianal manifestations of human immunodeficiency virus infection: experience with 200 patients. Dis Colon Rectum 1998;41:606-611

Gilliland R, Wexner SD. Sexually transmitted diseases. In: Surgery of the colon and rectum (1997) (ed Nicholls RD, Dozois RR). Churchill Livingstone, London