title: Metastatic nonpalpable invasive lobular breast carcinoma presenting as rectal stenosis: a case report.
abstract: BACKGROUND
  Invasive lobular carcinomas have an increased propensity for distant metastases, particularly to the peritoneum, ovaries, and uterus. In contrast, distant metastases of nonpalpable lobular carcinomas are extremely rare, and the causes of underlying symptoms of primary carcinomas remain unclear. We report a case of an asymptomatic invasive lobular carcinoma with a primary mammary lesion in a patient with rectal stenosis.
  
  
  METHODS
  A 69-year-old Japanese woman presented to our hospital for treatment of constipation. Although rectal stenosis was confirmed, thorough testing of her lower digestive tract did not identify its cause. Thus, an exploratory laparotomy and tissue biopsy was performed, and the presence of an invasive lobular carcinoma was confirmed. Subsequent breast examinations showed that the invasive lobular carcinoma that led to the rectal stenosis was a metastatic lesion from a primary lesion of the breast duct. As the present breast lobular carcinoma was asymptomatic and nonpalpable, we did not initially consider metastatic breast cancer as a cause of her symptoms, and the final diagnosis was delayed.
  
  
  CONCLUSIONS
  Peritoneal metastasis from nonpalpable invasive lobular carcinomas is very rare. However, breast cancer metastasis should be considered when carcinomatous peritonitis is present in a patient with an unknown primary cancer.
authors.affiliation: Department of Surgery, Division of Breast and Endocrine Surgery (Omori), Toho University School of Medicine, 6-11-1 Omori-Nishi, Ota-ku, Tokyo, 143-8451, Japan. tadatoshi.osaku@med.toho-u.ac.jp.
authors.forename: Tadatoshi
authors.initials: T
authors.lastname: Osaku
authors.affiliation: Department of Surgery, Division of Breast and Endocrine Surgery (Omori), Toho University School of Medicine, 6-11-1 Omori-Nishi, Ota-ku, Tokyo, 143-8451, Japan. ogatah@med.toho-u.ac.jp.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Ogata
authors.affiliation: Department of Surgery, Division of Breast and Endocrine Surgery (Omori), Toho University School of Medicine, 6-11-1 Omori-Nishi, Ota-ku, Tokyo, 143-8451, Japan. magosi@med.toho-u.ac.jp.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Magoshi
authors.affiliation: Department of Surgery, Division of Breast and Endocrine Surgery (Omori), Toho University School of Medicine, 6-11-1 Omori-Nishi, Ota-ku, Tokyo, 143-8451, Japan. yorichika.kubota@med.toho-u.ac.jp.
authors.forename: Yorichika
authors.initials: Y
authors.lastname: Kubota
authors.affiliation: Department of Surgery, Division of Breast and Endocrine Surgery (Omori), Toho University School of Medicine, 6-11-1 Omori-Nishi, Ota-ku, Tokyo, 143-8451, Japan. fumi311098040@yahoo.co.jp.
authors.forename: Fumi
authors.initials: F
authors.lastname: Saito
authors.affiliation: Department of Surgery, Division of Breast and Endocrine Surgery (Omori), Toho University School of Medicine, 6-11-1 Omori-Nishi, Ota-ku, Tokyo, 143-8451, Japan. sg0713sk@med.toho-u.ac.jp.
authors.forename: Shinsaku
authors.initials: S
authors.lastname: Kanazawa
authors.affiliation: Department of Surgery, Division of Breast and Endocrine Surgery (Omori), Toho University School of Medicine, 6-11-1 Omori-Nishi, Ota-ku, Tokyo, 143-8451, Japan. hironori@med.toho-u.ac.jp.
authors.forename: Hironori
authors.initials: H
authors.lastname: Kaneko
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology*; D018275:Carcinoma, Lobular / Q000473:pathology / Q000556:secondary*; D003251:Constriction, Pathologic; D057210:Delayed Diagnosis; D005260:Female; D006801:Humans; D007415:Intestinal Obstruction / Q000209:etiology*; D012004:Rectal Neoplasms / Q000473:pathology / Q000556:secondary*