False-negative anti-treponemal immunohistochemistry in secondary syphilis

Atypical presentation of secondary syphilis: annular lesions in an elderly patient

Syphilis is a chronic bacterial sexually transmitted infectious disease caused by Treponema pallidum. Different age groups are affected by heterogeneous clinical forms of the disease. We report a case of atypical secondary syphilis in an elderly patient with diffuse annular erythematous lesions on the chest, back, upper and lower limbs diagnosed by histopathological, immunohistochemical and serological tests.

Primary Anal Canal Syphilis in Men: The Clinicopathologic Spectrum of an Easily Overlooked Diagnosis

CONTEXT

The incidence of syphilis is on the rise, particularly in male patients who are human immunodeficiency virus (HIV) positive, and men who have sex with men.

OBJECTIVE

To describe 4 cases of primary syphilis presenting in the anal canal to increase awareness of its presentation and morphology in this location, as the diagnosis can be easily overlooked clinically and by the pathologist. Design .- Clinical presentation, hematoxylin-eosin-stained sections, and Treponema pallidum immunohistochemical staining were reviewed in detail in all 4 cases.

RESULTS

Three patients presented with anal canal ulcers; one presented with an ulcerated anal mass. All 4 patients were male, of whom 2 were HIV positive. Syphilis was clinically suspected in only 1 case; in 2 cases, confirmatory evaluation and treatment were prompted by pathologic diagnosis. In the fourth case, syphilis was diagnosed serologically at time of biopsy; however, the patient had an anal mass, and malignancy was clinically suspected. All 4 cases had bandlike chronic plasma cell-rich inflammation at the squamous epithelium and lamina propria junction; 2 cases had poorly formed granulomas. One case had concomitant rectal biopsy specimens with proctitis. Treponema pallidum immunohistochemistry highlighted homing of organisms in a perivascular pattern and at the junction of squamous epithelium and lamina propria.

CONCLUSIONS

Syphilis should be considered in the differential diagnosis of anal canal ulcers, anorectal inflammatory masses, and proctitis. Detailed knowledge of clinical history and recognition of the characteristic pattern of inflammation by the pathologist is important. Treponema pallidum immunohistochemical staining can help avoid a missed diagnosis of syphilis, which, if left unrecognized, can progress to late-stage disease with serious complications.

[Syphilis. Part 2: Laboratory diagnostics, therapy and prevention]

Sexually transmitted infections and sexually transmitted diseases such as syphilis are a great problem for public health systems worldwide. Syphilis can be curatively treated with penicillin after early diagnosis, competent therapy and consistent monitoring. The fundamentals of syphilis diagnostics are direct and serological methods for pathogen detection. Prevention of syphilis includes exposition prophylaxis and in particular the routine use of condoms and the consistent education of affected persons and their sexual contacts.