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.

Germline APC mutations in hepatoblastoma

“…In another colorectal cancer study, it was identified in four families but did not segregate with disease in any of the tested families; additionally, it was found in 8.3% (8/96) of controls and 6.4% (6/94) of sporadic colorectal cancer cases . A case report showed an association between this mutation and MUTYH polymorphism in a patient with Gardner's syndrome and nuchal fibromas . In our series, the patient with this mutation is 20 years old at the time of this report and no polyps have been found during routine follow up, suggesting that this specific APC variant is of doubtful clinical significance.…”

“…19 A case report showed an association between this mutation and MUTYH polymorphism in a patient with Gardner's syndrome and nuchal fibromas. 20 In our series, the patient with this mutation is 20 years old at the time of this report and no polyps have been found during routine follow up, suggesting that this specific APC variant is of doubtful clinical significance. Unraveling APC gene integrity, specifically as it relates to additional APC mutations and variants of unknown significance, and risk for HB, will require further evaluation on a larger scale.…”

Nuchal-type fibroma of the shoulder: A case report and review of the literature

“…Microscopically, the majority of nuchal-type fibromas are composed of haphazardly arranged thick collagen fibers. Fibroblasts are sparsely scattered between the collagen fibers (13,18,19). In addition, entrapped islands of adipose tissue and skeletal muscle are typically observed (1,3,13).…”

CYP2E1 Testis Expression and Alcoholmediated Changes of Rat Spermatogenesis Indices and Type I Collagen

“…As it was previously mentioned, these reactive oxygen species were reported to mediate the paracrine stimulation of type I collagen synthesis in different stages of this process (60) and caused genotoxic effects on rodent germ cells (61).…”