{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,1]],"date-time":"2026-08-01T01:03:50Z","timestamp":1785546230315,"version":"3.56.0"},"reference-count":25,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,7,16]],"date-time":"2025-07-16T00:00:00Z","timestamp":1752624000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Direcci\u00f3n General de Investigaciones de la Universidad Santiago de Cali"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Infectious Disease Reports"],"abstract":"<jats:p>Background and Aim: Syphilis, caused by Treponema pallidum, classically presents with genital or anal chancres; rectal involvement is rare and frequently misdiagnosed as inflammatory bowel disease or malignancy. We describe an unusually severe case of syphilitic proctitis in the setting of advanced HIV-related immunosuppression (CD4 39 cells\/\u00b5L), in which targeted immunophenotyping (ERG and CD38) was a valuable adjunctive tool in the differential diagnosis. Case Presentation: A 46-year-old man with a recent history of erosive gastritis and esophageal candidiasis presented after six months of unintentional 20 kg weight loss, profound fatigue, intermittent fevers, profuse diarrhea, and two episodes of hematemesis. Workup revealed a new diagnosis of HIV infection (CD4: 39 cells\/\u00b5L; viral load: 87,837 copies\/mL). Contrast-enhanced CT demonstrated uniform, concentric rectal wall thickening (\u201ctarget sign\u201d). Colonoscopic biopsy showed exuberant granulation tissue and dense plasma cell infiltrates. Immunohistochemistry revealed a dense infiltrate of CD38-positive plasma cells and ERG-positive endothelial proliferation. These findings, in the context of positive serology, were highly supportive of a spirochetal etiology and helped differentiate it from potential mimics. Serology was positive for latent late syphilis (VDRL 1:64). The patient received three weekly doses of intramuscular benzathine penicillin; lumbar puncture excluded neurosyphilis. Discussion: This is among the first reported cases of syphilitic proctitis in a patient with CD4 &lt; 50 cells\/\u00b5L, where advanced immunophenotyping differentiated syphilitic inflammation from neoplastic or inflammatory mimics. Profound immunosuppression accelerates disease progression and yields atypical clinical features. Conclusion: In HIV-infected patients with chronic rectal symptoms, especially those with CD4 &lt; 50 cells\/\u00b5L, syphilitic proctitis must be considered. Integration of radiologic assessment, histopathology with ERG\/CD38 staining, and serologic testing permits prompt diagnosis. Early benzathine penicillin therapy and rigorous clinical and serologic follow-up are essential to prevent complications, including neurosyphilis.<\/jats:p>","DOI":"10.3390\/idr17040085","type":"journal-article","created":{"date-parts":[[2025,7,16]],"date-time":"2025-07-16T15:48:22Z","timestamp":1752680902000},"page":"85","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Severe Rectal Syphilis in the Setting of Profound HIV Immunosuppression: A Case Report Highlighting ERG\/CD38 Immunophenotyping and a Review of the Literature"],"prefix":"10.3390","volume":"17","author":[{"given":"Diana Marcela","family":"Carmona Valencia","sequence":"first","affiliation":[{"name":"Specialization in Internal Medicine, Department of Health, Universidad Santiago de Cali, Cali 760035, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5305-4262","authenticated-orcid":false,"given":"Juan Diego","family":"L\u00f3pez","sequence":"additional","affiliation":[{"name":"Specialization in Internal Medicine, Department of Health, Universidad Santiago de Cali, Cali 760035, Colombia"},{"name":"Department of Research and Education, Cl\u00ednica de Occidente S.A., Santiago de Cali 760046, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shirley Vanessa","family":"Correa Forero","sequence":"additional","affiliation":[{"name":"Specialization in Internal Medicine, Department of Health, Universidad Santiago de Cali, Cali 760035, Colombia"},{"name":"Department of Research and Education, Cl\u00ednica de Occidente S.A., Santiago de Cali 760046, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Diana Marcela","family":"Bonilla Bonilla","sequence":"additional","affiliation":[{"name":"Specialization in Internal Medicine, Department of Health, Universidad Santiago de Cali, Cali 760035, Colombia"},{"name":"Department of Research and Education, Cl\u00ednica de Occidente S.A., Santiago de Cali 760046, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jorge Karim","family":"Assis","sequence":"additional","affiliation":[{"name":"Department of Research and Education, Cl\u00ednica de Occidente S.A., Santiago de Cali 760046, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2674-8725","authenticated-orcid":false,"given":"Yamil","family":"Liscano","sequence":"additional","affiliation":[{"name":"Specialization in Internal Medicine, Department of Health, Universidad Santiago de Cali, Cali 760035, Colombia"},{"name":"Grupo de Investigaci\u00f3n en Salud Integral (GISI), Departamento Facultad de Salud, Universidad Santiago de Cali, Cali 760035, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"rjac102","DOI":"10.1093\/jscr\/rjac102","article-title":"Diagnosis and Management of Rectal Syphilis\u2014Case Report","volume":"2024","author":"Afzal","year":"2024","journal-title":"J. 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