). Out of 391 cases of nasal and paranasal tumours reviewed by Ringertz (1938) and 64 similar cases reviewed by Benenati (1903), no tumours of skeletal muscle origin were found. During a six year period, , about 150 patients with histologically proven malignant diseases of the upper respiratory tract, were recorded in the Cancer Registry of the Pathology Department, University College Hospital, Ibadan. Of these, 5 patients (3 3 %) had rhabdomyosarcomas. In view of the relative rarity of this type of tumour in the upper respiratory tract, the clinicopathological features of the patients are presented and the ultra-structure of tumour from three patients are described.
MATERIALS AND METHODSBiopsy specimens for light microscopy were fixed in 10 % formol saline and stained with haematoxylin and eosin, phosphotungstic acid haematoxylin (P.T.A.H.), Heidenhain's iron haematoxylin and periodic acid Schiff. Tissues for electron microscopy were subsequently fixed in glutaraldehyde, post-fixed in osmium tetroxide, embedded in Epon, cut and stained with lead citrate. Sections were examined with an R.C.A. electron microscope.
CASE REPORTS
Case IThe patient was a 4[-year-old female, who presented with a 10-week history of progressive swelling of the right side of her nose which had been treated by topical applications by her parents for some time. On examination, there was a painless, pale, ulcerated, firm, lobulated tumour mass, measured 1 cm. in diameter, which involved the right nasal cavity, the right ala nasae and extended to the face across the nasofacial groove. The tumour was adherent to skin in places but mobile over deeper tissues. It expanded the nasal vestibule which it almost completely occluded. There was no cervical lymphadenopathy. The tumour mass, along with part of the ala nasae, was removed surgically. The tumour was not encapsulated but there was an apparent plane of cleavage between the tumour and surrouning tissues. There was no underlying bone destruction. The cavity thus created was packed, and postoperative recovery was uneventful. The patient was followed