Nerve sheath myxoma of the gingiva: report of a rare case and review of the literature.
BACKGROUND
Nerve sheath myxoma (NSM) is an extremely rare benign neoplasm in the oral cavity. This paper describes the first case, to our knowledge, of NSM in the gingival mucosa of an 84-year-old female patient.


METHODS
Intraoral examination revealed a painless and well-defined nodule in the lingual gingival mucosa of the right mandibular lateral incisor, which measured approximately 1.0 cm in diameter. The lesion was fully excised under local anesthesia, without intercurrences. Hematoxylin and eosin staining was performed in 5-microm sections for histopathologic analysis. Immunohistochemical reactions against vimentin and S-100 protein were carried out in 3-microm histologic sections in accordance with manufacturers' instructions.


RESULTS
The patient's medical history and an extraoral exam did not reveal other abnormalities. The patient wore a removable partial denture in the affected area. A trauma-induced gingival hyperplasia was the main diagnostic hypothesis. Microscopically, the lesion was composed of an abundant myxoid matrix and stellated and spindle-shaped cells arranged in lobules separated by fine fibrous septa. The cells presented strong positivity for vimentin and S-100 protein. According to the histopathologic and immunohistochemical features, the diagnosis of NSM was established. After 9 months of treatment, no signs or symptoms of recurrences have been observed.


CONCLUSIONS
Although NSM is an extremely rare oral tumor, it should be considered in the clinical differential diagnosis of gingival nodules.
Prado
José D
JD
Department of Stomatology, A.C. Camargo Cancer Hospital, São Paulo, SP, Brazil.
Andrade
Rodrigo G
RG
Silva-Sousa
Yara T C
YT
Andrade
Marília F
MF
Soares
Fernando A
FA
Perez
Danyel E C
DE
D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D005885:Gingival Hyperplasia / Q000175:diagnosis; D005887:Gingival Neoplasms / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D007180:Incisor / Q000473:pathology; D008334:Mandible / Q000473:pathology; D009232:Myxoma / Q000175:diagnosis* / Q000473:pathology; D018317:Nerve Sheath Neoplasms / Q000175:diagnosis* / Q000473:pathology; D009418:S100 Proteins / Q000032:analysis; D014746:Vimentin / Q000032:analysis
D009418:S100 Proteins; D014746:Vimentin