Abstract
Adult rhabdomyoma is a rare benign tumor of muscle origin favourably occurring in the head and neck regions, and only 60 cases of this disease have so far reported in the literatures concerned.
We recently experienced a case of adult rhabdomyoma appeared in the mouth floor. The patient was a 47 year old man who had first noticed a mass lesion on the right floor of the mouth approximately 1 year before. Because the tumor began to increase rapidly from about 3 months before, he visited our department September 1982. A reddish brown tumor of pigeon egg size was found on the right floor of the mouth. The tumor was surgically removed October 1982, which was subsequently revealed to be an elastic, encapsulated tumor of 58×52×28 mm in size.
Histological findings: The tumor was of solid type and consisted of large, round or polygonal cells with nuclei on the margin of cytoplasm. The cytoplasm was cosinophilic and contained many vacuoles. In some of these cells, stripes were found by staining with P TAH or Masson's trichrome specification. No cellular atypism or mitotic activity was observed.
Electron microscopic findings: There were many myofilaments and thickened Z-band in the cytoplasm of tumor cells.
