{
  "abstract": "Small bowel metastases from lung cancer may remain clinically occult until serious complications, including obstruction, bleeding, and perforation, occur. We report a case of perforated jejunal metastasis with a synchronous ileal metastasis at high risk of obstruction, identified during emergency surgery while several previously documented extraintestinal lesions had decreased in size. A 75-year-old woman with metastatic non-small cell lung carcinoma favoring adenocarcinoma had a programmed death-ligand 1 tumor proportion score of 95% and no targetable alteration on the companion-diagnostic panel. Pembrolizumab monotherapy (200 mg intravenously every 3 weeks) was administered for 4 cycles; no antiangiogenic agent had been administered concurrently or previously. Eleven days after the 4th dose, she developed acute abdominal pain. CT showed focal small bowel wall thickening, adjacent extraluminal air, diffuse bowel edema, and ascites. Emergency surgery revealed a perforated jejunal tumor approximately 20 cm distal to the ligament of Treitz. Systematic examination of the entire small bowel identified a 2nd, nearly circumferential ileal tumor approximately 15 cm proximal to the terminal ileum with marked luminal narrowing; both lesions were resected. Histopathological examination showed metastatic poorly differentiated adenocarcinoma of pulmonary origin. Neither tumor necrosis nor a histological treatment effect was identified, and the non-neoplastic mucosa showed no findings suggestive of immune checkpoint inhibitor-related enteritis. The patient was discharged on POD 19. Pembrolizumab was not resumed. PET-CT on POD 30 demonstrated widespread disease progression, and the patient transitioned to best supportive care. She died on POD 61 without recurrent gastrointestinal perforation, obstruction, or bleeding. Clinically occult small bowel metastases may present with perforation or impending obstruction during systemic therapy even while previously documented lesions at other sites decrease in size. Because the intestinal lesions were not identifiable before treatment, true discordant progression could not be established. Histopathological findings supported direct tumor-related perforation rather than treatment-induced tumor necrosis or immune-mediated enteritis. Emergency source control and systematic examination of the entire small bowel may identify additional lesions that alter operative management.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Surgery, JA Hokkaido Koseiren Abashiri-Kosei General Hospital, Abashiri, Hokkaido, Japan.",
    "Department of Surgery, Otaru General Hospital, Otaru, Hokkaido, Japan.",
    "Department of Diagnostic Surgical Pathology, JA Hokkaido Koseiren Sapporo Kosei General Hospital, Sapporo, Hokkaido, Japan.",
    "Department of Gastroenterological Surgery I, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan."
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Yoichi Miyaoka"
    },
    {
      "affs": [
        1
      ],
      "name": "Shingo Shimada"
    },
    {
      "affs": [
        2
      ],
      "name": "Yoshifumi Iwaguchi"
    },
    {
      "affs": [
        3
      ],
      "name": "Yoshikazu Ganchiku"
    },
    {
      "affs": [
        0
      ],
      "name": "Tomoya Saito"
    },
    {
      "affs": [
        0
      ],
      "name": "Ryoji Yokoyama"
    },
    {
      "affs": [
        0
      ],
      "name": "Daichi Hanaoka"
    },
    {
      "affs": [
        3
      ],
      "name": "Akinobu Taketomi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7xeg13x10wpc2.bib",
  "cited_by": 0,
  "doi": "10.70352/scrj.cr.26-0567",
  "fulltext_url": "https://europepmc.org/articles/PMC13739610",
  "id": "7xeg13x10wpc2",
  "issns": [
    "2198-7793"
  ],
  "landing_url": "https://europepmc.org/article/MED/42996562",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2740|Metastasis and carcinoma case studies"
    ]
  ],
  "openalex": "W7225090863",
  "pdf_url": "https://europepmc.org/articles/PMC13739610?pdf=render",
  "pmcid": "PMC13739610",
  "pmid": "42996562",
  "published": "2026-11-03",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7xeg13x10wpc2.ris",
  "sources": [
    {
      "first_seen": "2026-11-09T15:20:34Z",
      "native_id": "MED:42996562",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42996562"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2740|Metastasis and carcinoma case studies",
      "subfield": "general"
    }
  ],
  "title": "Emergency Resection for Perforated Small Bowel Metastasis from Primary Lung Cancer During Systemic Therapy: A Case Report.",
  "title_text": "Emergency Resection for Perforated Small Bowel Metastasis from Primary Lung Cancer During Systemic Therapy: A Case Report.",
  "type": "peer-reviewed",
  "updated_at": "2026-11-09T15:20:34Z",
  "url": "https://research.draconitic.com/paper/7xeg13x10wpc2",
  "venue": "Surgical case reports",
  "versions": []
}