Case Presentation: A 31-year-old man with past medical history of secondary syphilis and HIV/AIDS (CD4 47) intermittently on ART presented with worsening rectal pain and recurrent rectal abscesses. He endorsed rectal pruritis, nausea, weight loss, and lower extremity pain. He denied fevers, night sweats, abdominal pain, or diarrhea. Last year, he had a prior rectal abscess incised, drained, and treated with intravenous antibiotics. Examination revealed diffuse inguinal, perirectal, and cervical lymphadenopathy, and suprapubic tenderness. Additionally, he had a small perirectal ulcer at the 3 o’clock with no signs of drainage or fluid collection at site. There were no violaceous lesions visualized on the patient’s skin. Complete blood counts were notable for hemoglobin 13.3 and white blood cell count 7.2. CT abdomen and pelvis showed nonspecific proctitis with rectal wall thickening and induration of the perirectal fat extending to the presacral space. A rectal biopsy was positive for HHV-8 with histology and immunostaining pattern supporting Kaposi Sarcoma (KS) diagnosis. He was restarted on ART and rectal radiation initiated. Oncology planning to initiate liposomal doxorubicin.
Discussion: KS is a low-grade vascular tumor associated with human herpesvirus 8 (HHV-8) infection and typically presents as cutaneous lesions in immunocompromised individuals (1). While KS is rare in the ART-era, presentation involves skin involvement is most common with visceral organ and rectal involvement rare and associated with increased mortality and worse prognosis (2). KS of the rectum is often confused with herpetic ulcers, syphilis ulcers, or condyloma acuminata necessitating biopsy for diagnosis. Typically, gastrointestinal, and anorectal KS are diagnosed using endoscopic or, in more difficult cases, trans-rectal sonography or echoendoscopy-guided needle biopsy (3). Histopathology shows spindle cell predominance and immunohistochemical stains positive for CD34 and CD31 in 90% of cases (4). Treatment includes ART therapy and chemotherapy using liposomal doxorubicin for advanced disease.
Conclusions: In high-income countries, the incidence of KS has declined with the advent and ubiquitous use of ART. Presentation in internal organs without skin involvement remains uncommon, but isolated KS of the rectum is exceedingly rare. Rectal pain and pathology are common complaints for inpatient providers. The workup and differential are important for hospitalist to know. Therefore, in immunocompromised patients (such as HIV/AIDS), KS should be considered in the differential diagnosis for rectal ulcers. The work up in this population should include biopsies of the ulcers to rule-out advanced KS.