A 68-year-old woman was admitted to our hospital because of a rapid progression of renal dysfunction with positive myeloperoxidase antineutrophil cytoplasmic antibody and was diagnosed with rapidly progressive glomerulonephritis associated with microscopic polyangiitis (MPA). Severe right rectus sheath hematoma (RSH) bleeding from the inferior epigastric artery developed after starting hemodialysis, which required 4 transarterial embolizations due to recurrent bleeding. After additional treatment with methylprednisolone pulse therapy and rituximab, no rebleeding occurred. Although the giant hematoma reached the pelvis, it shrank spontaneously without any intervention. Nontraumatic RSH should therefore be considered when treating patients with multiple risk factors.

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease that can affect the gastrointestinal tract. Most cases of lupus enteritis (LE) involve the small intestine, while the involvement of the whole colon and rectum without the small intestine being affected is extremely rare.

A 35-year-old woman was diagnosed with colorectal LE after initially presenting with intermittent abdominal pain and vomiting for two months. She had a regular medication history for five years following the diagnosis of SLE but had been irregular in taking medications, which may have contributed to the onset of LE and led to her current hospital admission. According to the 2019 Classification criteria for SLE of the European League Against Rheumatism/American College of Rheumatology, this case scored 14. Additionally, abdominal computed tomography revealed significant wall edema of the colon and rectum, ischemia and hyperemia of the ascending colon intestinal wall, mesenteric vessel engorgement, increased mesangial fat attenuation, ascites, and bilateral ureter-hydronephrosis, all indicative of colon and rectum LE. Laboratory tests also showed lower levels of complement C3 and C4, with an antinuclear antibody titer of 1:100. Overall, it was clear that this case involved the colon and rectum without affecting the small intestine, representing a rare manifestation of SLE. The patient received treatment with 10 mg of methylprednisolone sodium succinate, 100 mL of 0.9% sodium chloride, hydroxychloroquine (100 mg), and nutrition support. After one week of methylprednisolone and hydroxychloroquine therapy, her SLE symptoms and disease activity improved significantly.

Although colorectal LE without small intestine involvement is very rare, early diagnosis and excellent management with corticosteroids prevented the need for surgical intervention. Physicians should be aware of colorectal LE without small intestine involvement as a manifestation of lupus flare.