Iwao Ohtani

Immunohistochemical evaluation with Ki-67: An application to salivary gland tumours

Using Ki-67, a monoclonal antibody, the proliferating capacity of 15 salivary gland tumours, including nine pleomorphic adenomas, four adenoid cystic carcinomas, one mucoepidermoid carcinoma and one acinic cell carcinoma was determined immunohistochemically, using normal salivary gland tissue as a control. The frequency of Ki-67 positive cells was 4.7 percent in the normal salivary gland and one percent in pleomorphic adenomas, whereas the average frequency in malignant tumours was 18.3 percent. Among adenoid cystic carcinomas, the frequency was related to the morphological type; the solid sub-type had the highest frequency of Ki-67-positive cells. As this sub-type is recognized as the most aggressive of these tumours, this technique has the potential of providing an early indication of the clinical behaviour of a tumour.

Chronic sinusitis and woodworking as risk factors for cancer of the maxillary sinus in Northeast Japan

In the period 1983 to 1985, 66 patients presented to six Japanese university hospitals with squamous cell carcinoma of the maxillary sinus. Using self‐administered questionnaires, a case‐control study was conducted to examine history of nasal diseases, occupational exposures, and other possible risk factors for this disease. For each patient, two controls were selected from the general population, matched to the patient by sex, age (± 5 years), and district of residence. A history of chronic sinusitis was associated with a 2.3‐fold increase in risk (p = 0.05). A high relative risk was also observed in males with an occupational history of woodworking or joinery, particularly when these jobs involved sanding or lathing practices (RR = 7.5, p = 0.02). No association between cigarette smoking and maxillary sinus cancer was observed in this study and no evidence was found that indoor air pollution in the home is involved in cancer development.

Why is otosclerosis of low prevalence in Japanese

Objective This study aimed to clarify the reasons why clinical otosclerosis, a very common disease among Caucasians, is not prevalent among Japanese. Study Design The incidence, site, activity, and volume of otosclerotic foci were examined in 1011 temporal bone sections from 507 Japanese individuals. Setting This study was prepared at the temporal bone laboratory, Fukushima Medical University, Fukushima. Results Otosclerotic foci were observed in 2.56% of individuals and in 1.48% of the ears. The most common site of involvement was anterior to the oval window region, but this was only in 38.9% of the ears with otosclerotic foci. The otosclerotic foci were not involved in the stapediovestibular articulation or the endosteal layer of the otic capsule in any ears. An active change of the otosclerotic focus was seen in 33.3% of ears with otosclerosis. The volume of otosclerotic foci at the site anterior to the oval window region was less than 0.8 mm3 in 5 out of 7 ears. Conclusion The incidence of histologic otosclerosis among Japanese seemed to be almost the same as that among Caucasians. Three reasons why clinical otosclerosis was not as prevalent among Japanese as among Caucasians are suggested: low incidence of involvement of foci anterior to the oval window, low activity, and small lesion without involvement of the footplate and/or membranous labyrinth of the inner ear.

Temporal bone histopathology in trisomy 22

Trisomy 22 has multiple physical anomalies, and aural malformations are commonly associated with trisomy 22. However, there has been only one report describing the temporal bone histopathology in trisomy 22. Our case is the second reported temporal bone histopathology of trisomy 22. Aural anomalies in this case were less serious than those earlier described, though showing Mondini dysplasia of the bony and membranous labyrinth. Deafness in patients with trisomy 22 may manifest sensorineural, conductive or mixed hearing losses, and/or vestibular dysfunction of varying degrees, according to the site and severity of aural anomalies.

Bilateral Parotid Gland Basal Cell Adenomas

We report a 65-year-old female with basal cell adenomas arising in the left and right parotid glands and review the literature. Diagnosis was based on clinical features, ultrasonographic and CT findings as well as histopathological examination. Parotid tumours usually arise on one side and bilateral occurrence is rare, accounting for 1–3% of all parotid tumours. Most bilateral parotid tumours are Warthin’s tumours and pleomorphic adenomas, and bilateral basal cell adenomas of the parotid glands are very rare and only 5 cases including ours have been reported. The exact mechanisms contributing to the development of bilateral parotid tumours remain unknown. We speculate on the involvement of environmental and genetic factors since the histological features of both parotid tumours are identical in most cases.

Temporal Bone Pathology in Intracochlear Schwannoma with Profound Hearing Loss

Intracochlear schwannoma was found in the temporal bone of a 85-year-old man in whom audiometric study, 26 days before death, had shown total deafness in the left ear. The tumor occupied the entire lumen of the cochlea in the basal turn involved Rosenthals canal, but it occupied only the scala tympani in the second turn. Intralabyrinthine schwannomas are difficult to diagnose by clinical examination. They were discovered accidentally during destructive labyrinthectomy for presumed Ménières disease or discovered incidentally by postmortem temporal bone pathology. Although intralabyrinthine schwannomas are a rare occurrence and cannot usually be diagnosed without surgery or postmortem histopathology, it is important to suspect the possibility of their existence in differential diagnosis of atypical Ménières disease or unilateral idiopathic progressive deafness. Long-term follow-up is obviously necessary to exclude the tumor.

Bone destruction resulting from rupture of a cholesteatoma sac: temporal bone pathology.

Objective: The purpose of the current study was to research the pathogenesis of bony destruction of cholesteatoma. Study Design: We conducted a case report. Setting: The study was performed at Fukushima Medical University. Patients: The first case involved a 21 trisomy, whereas the second case was cancer of the hypopharynx. Both cases showed cholesteatoma. Results: The following histopathologic findings in the temporal bones of cholesteatoma were obtained. Bony destruction in cholesteatoma was detected in the lesion of the rupture of the cholesteatoma sac. Epithelial debris of cholesteatoma was scattered throughout the rupture of the cholesteatoma sac. Rupture of the matrix was the result of a small abscess. Conclusion: Rupture of the cholesteatoma sac was believed to have been a pathway of either endogenous substances from the matrix and/or epithelial debris of cholesteatoma.

Individual Variation and Mechanism of Kanamycin Ototoxicity in Rabbits

In order to elucidate the mechanism of individual variation of kanamycin ototoxicity, the possible relationship between the outer hair cell damage induced by kanamycin and the levels of kanamycin in serum or perilymph and of renal damage was investigated in rabbits. No relationship was found between the extent of the outer hair cell damage and the level of kanamycin in the serum or the renal damage. The extent of the outer hair cell damage was closely correlated to the levels of kanamycin in the perilymph. These findings suggest that the individual variations in the outer hair cell damage induced by kanamycin are more closely correlated to the individual differences in the transferability of kanamycin into inner ear than to those in the vulnerability of the outer hair cells or kidneys.

Histochemical localization of carbonic anhydrase in the trachea of the guinea pig

Tissue specimens from guinea pigs were examined using an enzyme-histochemical reaction to explore the presence of carbonic anhydrase (CA) activity in the trachea. CA activity was detected in a group of morphologically distinct epithelial cells, in goblet cells, and in glands of the tracheal mucosa. The epithelial cells showing CA activity were distributed singly and sparsely throughout the entire trachea. These cells showed a wide morphological variability and were clearly different from those forming the pseudostratified ciliated epithelium. Their number was higher in sections closer to the tracheal bifurcation than in those near the larynx. Although the nature of these cells is unknown, based on their morphological and histochemical characteristics and their distribution, they may represent a specialized chemoreceptor. To our knowledge, this is the first report of CA localized in tracheal epithelial cells.

Mechanism of Protective Effect of Fosfomycin Against Aminoglycoside Ototoxicity

The purpose of this study was to clarify the mechanism of the protective effect of fosfomycin (FOM) against inner ear damage induced by an aminoglycoside dibekacin (DKB), when administered concurrently DKB and FOM. Rats were treated with 50 mg/kg of DKB with or without 500 mg/kg of FOM for short-term administration. No significant difference was seen in the serum peak level and in the area under the curve between the group receiving DKB alone and the combined administration group of DKB and FOM. On the other hand, the DKB level in the kidney was significantly lower in the combined administration group than in the group receiving DKB alone. The mechanism of protective effect of FOM against DKB-induced ototoxicity may be considered as follows: FOM inhibits the accumulation of DKB in the kidney and reduces its concentration in the kidney and serum. Consequently, the transferability of DKB into the inner ear is decreased, and finally inner ear damage is reduced.