Beyond the Bowels: Immune Thrombocytopenic Purpura Presents as a Rare Extraintestinal Manifestation of Ulcerative Colitis

Background: Ulcerative colitis (UC) is an inflammatory bowel disease marked by persistent inflammation in the colon’s mucosa, affecting the rectum and colon continuously. It follows a pattern of remission and recurrence and can have extraintestinal manifestations (EIMs). Common EIMs include arthritis, primary sclerosing cholangitis, metabolic bone disease, and uveitis, although these are more frequent in Crohn’s disease patients. Hematological issues, such as coagulopathies like pulmonary thromboembolism and deep vein thrombosis, are rare in UC. Immune thrombocytopenic purpura (ITP) is characterized by the presence of autoantibodies against platelet membrane antigens, leading to immune-mediated platelet destruction. The disease affects mostly women which may manifest as petechiae, purpura, cutaneous, and mucous ecchymosis, alongside isolated thrombocytopenia. The differential diagnoses include hemolytic uremic syndrome, disseminated intravascular coagulation, paroxysmal nocturnal hemoglobinuria, myelodysplastic syndrome, lymphoproliferative disorders, infection (human immunodeficiency virus, hepatitis C), and thrombocytopenia induced by drugs such as alcohol and heparin. ITP is considered as a rare extraintestinal manifestation (EIM) of ulcerative colitis (UC). The link between inflammatory bowel disease (IBD) and Immune Thrombocytopenic Purpura (ITP) is thought to be due to similarities between the gut lining and platelet membrane antigens. This similarity can trigger an immune response that leads to platelet destruction in the spleen. The treatment of ITP includes the use of immunosuppressants, such as corticosteroids, intravenous gamma globulin, or anti-D immunoglobulin, as first-line therapies. However, in cases of ITP associated with IBD, medications that target both conditions can be used. This case report aimed to describe a rare case of UC associated with ITP. Methods: A 26-year-old male with an unremarkable medical history presented with a chief complaint of hematochezia and abdominal pain persisting for the past month. Laboratory results indicated mild anemia (hemoglobin level: 12.0 g/dL) and notable thrombocytopenia (platelet count: 18,000/mm³). Abdominal CT scan revealed signs of rectosigmoid colitis. Elevated ESR levels and an increased fecal calprotectin concentration were also noted. Initially, a hematologist evaluated the thrombocytopenia, ruling out infectious and autoimmune factors. The patient received a two-day course of IV Immunoglobulin (80 grams daily). Simultaneously, colitis management involved IV ciprofloxacin (400 mg twice daily) and IV metronidazole (500 mg three times daily). Results: On day 9, there was an improvement in the platelet count, and a colonoscopy was performed. It revealed foggy, erythematous, friable mucosa extending 18cm from the anus. Biopsy results indicated mild chronic inflammation, congestion, and hemorrhage in the cecum with focal cryptitis, crypt abscess, and crypt loss, suggestive of Ulcerative colitis. The patient was subsequently treated with oral mesalamine (800 mg thrice daily) and rectal suppository mesalamine (1000 mg daily). The patient experienced clinical improvement and has been consistently following up as an outpatient. Conclusions: ITP is a rare EIM present in patients with UC. The presence of thrombocytopenia accompanied by gastrointestinal symptoms should raise suspicion about this condition. Accurate diagnosis of this unusual presentation and appropriate treatment are crucial to control the condition, prevent complications, and improve the patient’s prognosis.