title: Metastatic lobular carcinoma of the breast masquerading as a primary rectal cancer.
abstract: BACKGROUND
  Colorectal metastasis of lobular carcinoma of the breast is a diagnostic challenge. It may macroscopically simulate primary colon cancer or inflammatory bowel disease. In some cases, the interval between the primary breast cancer and metastatic colorectal lesions is so long that the critical records for diagnosis including history might be lost or missed.
  
  
  METHODS
  Reported herein is a case of metastatic lobular carcinoma of the breast masquerading as a primary rectal cancer developed in a 62-year-old Japanese woman. The case initially presented as a circumferential rectal lesion, and information on the patient's history of breast cancer was not noted. As the result of endoscopic biopsy, diagnosis of poorly differentiated rectal adenocarcinoma was made. The lesion was surgically resected after chemo-radiotherapy. Histopathological examination of the resected specimen with hematoxylin and eosin (HE) stain revealed a single-file arrangement of the tumor cells, reminiscent of lobular carcinoma of the breast. Immunohistochemical analysis revealed an immunophenotype consistent with lobular carcinoma of the breast. Because further review of the patient's history revealed an occurrence of 'poorly differentiated adenocarcinoma of the breast', which she had experienced 24 years earlier, the final diagnosis of the lesion was made as rectal metastasis from lobular breast carcinoma.
  
  
  CONCLUSIONS
  Poorly differentiated adenocarcinoma of the colorectum is rarer than that of the stomach. Linitis plastica-type cancer of the colorectum is also rarer than that of the stomach. A lesson from the present case is that before we conclude a linitis plastica-type cancer of poorly differentiated type as a primary colorectal cancer, it is critical to exclude a possibility of metastatic colorectal cancer.
authors.affiliation: Department of Surgical Pathology, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Matsuda
authors.forename: Nagahide
authors.initials: N
authors.lastname: Matsubara
authors.forename: Nobuo
authors.initials: N
authors.lastname: Aoyama
authors.forename: Mie
authors.initials: M
authors.lastname: Hamanaka
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamagishi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kuno
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Tsukamoto
authors.forename: Tomoki
authors.initials: T
authors.lastname: Yamano
authors.forename: Masafumi
authors.initials: M
authors.lastname: Noda
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ikeuchi
authors.forename: Naohiro
authors.initials: N
authors.lastname: Tomita
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hirota
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D018275:Carcinoma, Lobular / Q000473:pathology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000473:pathology / Q000556:secondary*