Pseudosarcomatous fasciitis, a non-neoplastic connective-tissue proliferation, usually occurs on the trunk or extremities of young adults; it appears as a rapidly growing nodule that histologically imitates a malignant mesenchymal neoplasm but that clinically behaves benignly. Many cases have been origi-
nally mistaken as sarcomas due to the spindle cell nature and cellularity. Nodular fasciitis has distinctive microscopic features that allow for the diagnosis, and the predominant cell type is the myofibroblast. Similar lesions have been described intraorally and in the head and neck regions.
Proliferative myositis and focal myositisare lesions of skeletal muscle that have similar clinical features that are identified on the basis of the histologic picture. Rare cases have been described in the tongue and in other neck and jaw muscles. Biologically, proliferative myositis is a reactive fibroblastic lesion that infiltrates around individual muscle fibers. Despite the nomenclature, these lesions are not inflamed histologically.
Proliferative myositis and focal myositisare lesions of skeletal muscle that have similar clinical features that are identified on the basis of the histologic picture. Rare cases have been described in the tongue and in other neck and jaw muscles. Biologically, proliferative myositis is a reactive fibroblastic lesion that infiltrates around individual muscle fibers. Despite the nomenclature, these lesions are not inflamed histologically.