title: Extra nuchal-type fibroma associated with elastosis, traumatic neuroma, a rare APC gene missense mutation, and a very rare MUTYH gene polymorphism: a case report and review of the literature*.
abstract: We report a case of an extra nuchal-type fibroma in a 51-year-old male suspected to have attenuated familial adenomatous polyposis (Gardner's syndrome), who presented with a longstanding buttock mass excised due to enlargement and pain. Histopathologically, lobules of haphazard, hypocellular, hyalinized collagen bundles replaced the dermis and subcutis and entrapped nerve bundles, mimicking Morton neuroma. Ramifying nerve twigs found around larger nerve fascicles showed the co-existence of traumatic neuroma. Elastic tissue stain revealed elastosis characterized by large, arborizing fibers lying between and within the hyalinized collagen bundles. Modified Masson's trichrome stain showed light blue staining of collagen bundles producing the hyalinized nodules with irregular, light red staining of collagen bundles at their periphery and within tumor collagen. Compression and/or degeneration of collagen and secondary elastosis with later entrapment by tumor collagen could explain this microscopic phenotype. By immunohistochemistry, tumor spindle cells expressed nuclear β-catenin and cyclin D1, mostly within regions of fibrosis implicating activation of the adenomatous polyposis coli (APC)-Wnt pathway. Genetic analysis showed a missense mutation in APC gene (c.7504G>A, p.G2502S in exon 15) and a functional homozygous polymorphism in the MUTYH gene (c.36+325G>C, (IVS1+5G/C)). Nuchal-type fibroma has been associated with Gardner's syndrome and trauma. In this patient, genetic predisposition coupled with repetitive, localized trauma and collagen degeneration may have provided the stimulus for the development of extra nuchal-type fibroma.
authors.affiliation: Department of Pathology, Albany Medical College MC-81, Albany, NY 12208, USA.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Linos
authors.forename: Monika
authors.initials: M
authors.lastname: Sedivcová
authors.forename: Katerina
authors.initials: K
authors.lastname: Cerna
authors.forename: Radek
authors.initials: R
authors.lastname: Sima
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Kazakov
authors.forename: Tipu
authors.initials: T
authors.lastname: Nazeer
authors.forename: Alexey
authors.initials: A
authors.lastname: Glazyrin
authors.forename: Brian T
authors.initials: BT
authors.lastname: Valerian
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Carlson
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D045647:DNA Glycosylases / Q000235:genetics* / Q000378:metabolism; D005148:Facial Dermatoses / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D005350:Fibroma / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D005736:Gardner Syndrome / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D017491:Genes, APC; D006801:Humans; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D009463:Neuroma / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D011110:Polymorphism, Genetic; D012983:Soft Tissue Neoplasms / Q000235:genetics / Q000473:pathology* / Q000601:surgery
chemical_list: C555337:APC protein, human; D025601:Adenomatous Polyposis Coli Protein; D014408:Biomarkers, Tumor; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase