DESMOID-TYPE FIBROMATOSIS OF THE BUCCAL MUCOSA: A CASE REPORT

Abstract

Desmoid-type fibromatosis is a rare benign mesenchymal lesion that originates from musculoaponeurotic structures and rarely occurs in the head and neck region. The 32-year-old male patient was referred for evaluation of a submucosal lesion located in the left buccal mucosa, which was hardened, was painless, and had 3 months of evolution. Ultrasonography showed a well-defined, anechoic, and hypovascular mass. The histopathologic analysis showed proliferation of elongated, spindle-shaped cells of uniform appearance exhibiting condensed chromatin and eosinophilic cytoplasm with imprecise limits, sometimes with fasciculate pattern, associated with areas of prominent fibrosis with thick bundles of collagen. The proliferation produces dissociation and degeneration of muscle fibers. Immunohistochemical reaction revealed, in tumor cells, negativity for protein S100 and CD34 besides immunoexpression focal positive for α actin and β catenin. The cells strongly expressed vimentin. Morphologic and immunohistochemical findings were compatible with desmoid type fibromatosis. The patient is under clinical follow-up of 8 months without relapse. Desmoid-type fibromatosis is a rare benign mesenchymal lesion that originates from musculoaponeurotic structures and rarely occurs in the head and neck region. The 32-year-old male patient was referred for evaluation of a submucosal lesion located in the left buccal mucosa, which was hardened, was painless, and had 3 months of evolution. Ultrasonography showed a well-defined, anechoic, and hypovascular mass. The histopathologic analysis showed proliferation of elongated, spindle-shaped cells of uniform appearance exhibiting condensed chromatin and eosinophilic cytoplasm with imprecise limits, sometimes with fasciculate pattern, associated with areas of prominent fibrosis with thick bundles of collagen. The proliferation produces dissociation and degeneration of muscle fibers. Immunohistochemical reaction revealed, in tumor cells, negativity for protein S100 and CD34 besides immunoexpression focal positive for α actin and β catenin. The cells strongly expressed vimentin. Morphologic and immunohistochemical findings were compatible with desmoid type fibromatosis. The patient is under clinical follow-up of 8 months without relapse.