Cutaneous Kaposi’s Sarcoma Following Long-Term Infliximab Treatment in a Patient with HIV-Negative Antibiotic-Dependent Chronic Pouchitis: Considerations on an Exceptional Finding

In managing ulcerative colitis (UC), anti-tumour necrosis factor (TNF) agents are among the primary choices. Evidence suggests anti-TNF does not significantly increase malignancy risk (apart from lymphoma and melanoma), though uncertainties persist due to inconsistent long-term data. Kaposi’s sarcoma (KS), induced by human herpesvirus type-8 (HHV-8), is a multifocal neoplasm linked to immunosuppressive therapies, primarily affecting the skin and gastrointestinal tract. KS cases during anti-TNF therapy for UC are anecdotal. We report a rare occurrence of KS in the setting of the long-term use of the standard maintenance dose of infliximab (initiated in 2010) in a 56-year-old male patient with UC diagnosed in 2001. The patient underwent restorative proctocolectomy with ileal J-pouch-anal anastomosis in 2002 and subsequently developed chronic antibiotic-dependent pouchitis. Given the secondary loss of response to infliximab, a switch to vedolizumab was performed. In April 2024, the patient reported the presence of a skin lesion on the right leg. Following surgery, a rhomboid-shaped skin area was removed, encompassing the irregular, greyish KS lesion. The histopathological analysis confirmed the diagnosis of patch-like KS. We continued vedolizumab due to its gut-selective profile. The patient is in clinical remission and under dermatological follow-up with no lesion recurrence.