title: Spontaneous infarcted adenoma of the mammary gland in a Wistar Hannover GALAS rat.
abstract: Spontaneous massive infarction of mammary gland tumors has been reported to occur infrequently in humans. A subcutaneous mass (18 × 17 × 10 mm) was observed in the right axilla extending to the chest region of a 110-week-old female Wistar Hannover GALAS rat. Histopathologically, a well-circumscribed mass with lobular structures was present in the subcutis. Most of the mass was occupied by extensive coagulative necrosis of neoplastic cells with relatively uniform acinar and ductal structures. Although each necrotic acinar structure was separated by reticular fibers, periacinar stromal collagen fibers were not abundant. Considering the site of occurrence and histological features, the necrotic tissue was diagnosed as adenoma of the mammary gland. The necrotic region lacked hemorrhage and obvious inflammatory cell infiltration, indicating the necrosis was caused by infarction. Although multiple necrosis and focal infarction are occasionally observed in large-sized tumors in rodents, especially in adenocarcinomas, the present case was characteristic, with the massive infarction involving most parts of the tumor despite the relatively small size and low atypia of neoplastic cells. This is a rare case of spontaneous infarcted adenoma of the mammary gland in rats histologically resembling human cases.
authors.affiliation: Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Matsushita
authors.affiliation: Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Toyoda
authors.affiliation: Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Morikawa
authors.affiliation: Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan; Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo183-8509, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Sone
authors.affiliation: Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Ogawa
keywords: Wistar Hannover GALAS rat; infarcted adenoma; mammary gland; spontaneous lesion