{
  "abstract": "Pituitary metastases are uncommon, and most cases originate from breast or lung cancer. Tumor-to-tumor metastasis, in which one neoplasm metastasizes into another, is particularly rare in the sellar region. We report a 66-year-old man with metastatic sigmoid colon adenocarcinoma treated with modified FOLFOX6 (5-fluorouracil, L-leucovorin, and oxaliplatin) plus panitumumab; extracranial disease was controlled, whereas a sellar mass initially suspected as a pituitary adenoma slowly enlarged over 2 years. Endocrine testing showed anterior hypopituitarism without arginine vasopressin deficiency. Endoscopic transsphenoidal surgery was performed for continued enlargement and diagnostic uncertainty. Histopathology demonstrated a gonadotroph pituitary adenoma infiltrated by colorectal adenocarcinoma, with extensive intermingling of the 2 components rather than discrete nests, favoring tumor-to-tumor metastasis over a collision tumor. The metastatic component consisted of viable tumor cells without necrosis or convincing treatment effect despite prolonged chemotherapy. This case underscores that metastatic tumor within a pituitary adenoma may enlarge despite favorable systemic therapy outcomes. Metastasis should therefore remain a key differential diagnosis for a sellar mass radiologically suggestive of a pituitary adenoma.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Endocrinology and Metabolism, Hirosaki University Graduate School of Medicine, Hirosaki 036-8562, Japan.",
    "Department of Pathology, Moriyama Memorial Hospital, Tokyo 134-0081, Japan."
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Shingo Murasawa",
      "orcid": "0000-0002-6531-9923"
    },
    {
      "affs": [
        0
      ],
      "name": "Fumiya Isozaki",
      "orcid": "0009-0003-4053-9844"
    },
    {
      "affs": [
        1
      ],
      "name": "Miku Fukasawa-Maeda",
      "orcid": "0000-0002-5073-0672"
    },
    {
      "affs": [
        0
      ],
      "name": "Shinobu Takayasu",
      "orcid": "0000-0003-4759-6166"
    },
    {
      "affs": [
        1
      ],
      "name": "Naoko Inoshita",
      "orcid": "0000-0002-5459-3388"
    },
    {
      "affs": [
        0
      ],
      "name": "Yukihiro Fujita",
      "orcid": "0000-0003-3238-8743"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8gw8yb11v3x8v.bib",
  "cited_by": 0,
  "doi": "10.1210/jcemcr/luag325",
  "fulltext_url": "https://europepmc.org/articles/PMC13687892",
  "id": "8gw8yb11v3x8v",
  "issns": [
    "2755-1520"
  ],
  "landing_url": "https://europepmc.org/article/MED/42923192",
  "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",
      "2712|Pituitary Gland Disorders and Treatments"
    ]
  ],
  "openalex": "W7223187367",
  "pdf_url": "https://europepmc.org/articles/PMC13687892?pdf=render",
  "pmcid": "PMC13687892",
  "pmid": "42923192",
  "published": "2026-10-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/8gw8yb11v3x8v.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:33Z",
      "native_id": "MED:42923192",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42923192"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2712|Pituitary Gland Disorders and Treatments",
      "subfield": "endocrinology-metabolism"
    }
  ],
  "title": "Tumor-to-tumor metastasis of colorectal adenocarcinoma within a gonadotroph pituitary adenoma.",
  "title_text": "Tumor-to-tumor metastasis of colorectal adenocarcinoma within a gonadotroph pituitary adenoma.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:20:33Z",
  "url": "https://research.draconitic.com/paper/8gw8yb11v3x8v",
  "venue": "JCEM case reports",
  "versions": []
}