title: Collagenoma in an African Clawed Frog (Xenopus laevis).
abstract: A 3-y-old female Xenopus laevis was reported for a gray mass on the abdomen. The frog was used for egg collection and was otherwise experimentally naïve. On physical exam, the frog was bright and active and had a firm, gray, lobulated mass (1.5 cm × 0.5 cm × 0.5 cm) in the cutaneous tissue of the left lateral abdomen. An excisional biopsy was performed under anesthesia, and the entire mass was removed and processed for histopathology. Microscopically, the dermis was greatly expanded by connective tissue with a marked decrease in the number of glands, and occasional degenerative glands were present. When stained with Masson trichrome, the excessive connective tissue stained blue, indicating that it was composed of collagen. With Verhoeff-van Gieson staining, the connective tissue stained bright red with an absence of black-staining material, demonstrating the presence of collagen and ruling out elastic fibers. In light of the morphology of the mass and the results of the special stains, the mass was diagnosed as a collagenoma. To our knowledge, this report is the first description of a collagenoma in X. laevis.
authors.affiliation: Department of Pathobiology, University Laboratory Animal Resources, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Johnston
authors.affiliation: Department of Pathobiology, University Laboratory Animal Resources, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Blythe H
authors.initials: BH
authors.lastname: Philips
authors.affiliation: University Laboratory Animal Resources, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Carty
authors.affiliation: Department of Medicine, School of Veterinary Medicine, University Laboratory Animal Resources, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Klein
authors.affiliation: Department of Pathobiology, University Laboratory Animal Resources, University of Pennsylvania, Philadelphia, Pennsylvania, USA. abrice@upenn.edu.
authors.forename: Angela K
authors.initials: AK
authors.lastname: Brice
mesh_terms: D000008:Abdominal Neoplasms / Q000737:chemistry / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D000818:Animals; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy / Q000662:veterinary; D003094:Collagen / Q000032:analysis; D003095:Collagen Diseases / Q000378:metabolism / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D005260:Female; D012878:Skin Neoplasms / Q000737:chemistry / Q000601:surgery / Q000662:veterinary*; D013194:Staining and Labeling / Q000662:veterinary; D014982:Xenopus laevis
chemical_list: D014408:Biomarkers, Tumor; D003094:Collagen