Adult extracardiac rhabdomyoma: light and immunohistochemical studies of two cases in the parapharyngeal space.
BACKGROUND
We present two cases of adult rhabdomyoma in the parapharyngeal space. They are rare benign tumors with a characteristic histologic appearance.


METHODS
The tumors were studied by light and immunohistochemical analysis using stains characteristic of striated muscle fibers.


RESULTS
Cross-striation was demonstrated by phosphotungstic acid hematoxylin (PTAH), muscle specific actin, desmin, and myoglobin while dystrophin was expressed in the cell membranes. Clonal origin was confirmed by expression of myosin heavy chain-fast only. Expression of myosin-neonatal and myogenin proved slight proliferation with incipient differentiation in an otherwise mature tumor.


CONCLUSIONS
The head and neck area harbors 90% of adult rhabdomyomas and should be considered in a differential diagnosis in this region. Immunohistochemistry confirms that the tumors are almost totally mature neoplasms of clonal origin.
Bjørndal Sørensen
Kristine
K
Department of Pathology, Odense University Hospital, DK-5000 Odense C, Denmark.
Godballe
Christian
C
Ostergaard
Birthe
B
Krogdahl
Annelise
A
D000368:Aged; D003893:Desmin / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009124:Muscle Proteins / Q000378:metabolism; D010610:Pharyngeal Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D012207:Rhabdomyoma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery
D003893:Desmin; D009124:Muscle Proteins