Collagenolytic activity in middle ear cholesteatoma

Cholesteatoma of Maxillary Sinus: What Is the Best Surgical Approach?

Cholesteatoma is a relatively common disease entity within the middle ear or mastoid cavity but cholesteatoma of the paranasal sinuses is a rare diseases entity, especially in the maxillary sinus. As the authors recently experienced a patient of maxillary sinus cholesteatoma, the authors tried to review all the literatures previously reported on the "Cholesteatoma of the maxillary sinus." The aim of this study was to describe authors' recent experience and review previously reported patients of cholesteatoma of the maxillary sinus. Additionally, it is to describe the clinical features focusing on the computed tomography findings and to elucidate which approach may be best for complete excision. The authors thoroughly reviewed 10 patient reports written in English regarding the cholesteatoma of maxillary sinus which have been published since the 1980s. Based on authors' review, the authors suggest some conclusions. First, the diagnosis of cholesteatoma, although rare, should be considered for any slowly expansile lesion of the maxillary sinus. Second, there was no specific computed tomography finding that was helpful for the diagnosis of maxillary sinus cholesteatoma. Last, the surgical approach to cholesteatoma of the maxillary sinus should be chosen to allow visibility and complete removal according to the size, location, and extent of diseases.

The Surgical Management of Labyrinthine Fistulae in Chronic Otitis Media with Cholesteatoma

The author's series of 168 consecutive cases of chronic otitis media from the years 1965 to 1972 were reviewed with regard to the occurrence and management of pathological fistulae in the bony labyrinth. Fourteen cases (incidence 8.3%), of which nine involved only the semicircular canals and five involved primarily the cochlear wall occasionally associated with a semicircular canal fistula, were examined particularly in terms of postoperative sensorineural hearing loss following removal of cholesteatoma matrix from the fistula. The results indicated that the matrix can be removed with reasonable safety from most small semicircular canal fistulae. Only when the cholesteatoma matrix is firmly adherent to a large area of membranous semicircular canal is removal not recommended. When the cholesteatoma was removed from three cochlear fistulae, sensorineural hearing loss resulted. In two cases with cochlear fistula, hearing was preserved when the cholesteatoma matrix was not removed from the fistulized area. These results have been used to formulate guidelines for the surgical management of pathological fistulae of the bony labyrinth.

Etiopathogenesis of cholesteatoma

Cholesteatoma is a destructive lesion of the temporal bone that gradually expands and causes complications by erosion of the adjacent bony structures. Bone resorption can result in destruction of the ossicular chain and otic capsule with consecutive hearing loss, vestibular dysfunction, facial paralysis and intracranial complications. Surgery is the only treatment of choice. The etiopathogenesis of cholesteatoma, however, is still controversial. This review was designed to understand the reasons for these disparities and to reduce or eliminate them. Future studies focused on developmental, epidemiological, hormonal and genetic factors as well as on treatment are likely to contribute to further understanding of cholesteatoma pathogenesis.

Inhibition of matrix metalloproteinases in gerbil cholesteatoma: preliminary findings

OBJECTIVES

This study was conducted to examine the role of matrix metalloproteinases (MMPs) and the impact of a topical MMP inhibitor, ilomostat, on the development of tympanic membrane (TM) atelectasis in the gerbil model.

METHODS

Eustachian tubes were cauterized bilaterally in 19 gerbils. Thereafter, both TMs received once-daily topical treatment for 8 weeks with ilomostat or vehicle or no treatment (n = 6 or 7 per group). TM atelectasis was serially graded, and TMs were harvested at 8 weeks. Gelatin zymograms were performed to determine MMP activity.

RESULTS

The mean activity levels of proenzyme and active MMP-9 and MMP-2 and degree of atelectasis did not differ between groups. TM atelectasis did not correlate to levels of enzymes across individual samples.

CONCLUSIONS

Topical application of an MMP inhibitor did not significantly prevent the development of TM atelectasis. It remains to be determined whether the use of MMP inhibitors may prevent the progression of atelectasis in humans.

Localization of matrix metalloproteinase 1 in cholesteatoma and deep meatal skin

HYPOTHESIS

Matrix metalloproteinase 1 (MMP-1) is overexpressed in cholesteatoma.

BACKGROUND

Cholesteatoma destroys bone, whereas deep meatal skin does not. MMP-1 is a type I collagenase that may be responsible for this destruction. This prospective study was designed to identify overexpression of MMP-1 by cholesteatoma in comparison with deep meatal skin.

METHODS

Ten cholesteatoma specimens and nine deep meatal skin specimens were removed during otologic surgery and then fixed in formalin and embedded in paraffin. Immunocytochemistry studies were performed using a monoclonal antibody to MMP-1. A pathologist assessed the slides in a blinded fashion. Expression of MMP-1 protein in epidermis and in stroma was scored from 0 to 10. Five further cholesteatoma specimens and three deep meatal skin specimens underwent reverse transcriptase polymerase chain reactions to assess messenger ribonucleic acid production. Paired and unpaired Student's t tests were used to assess the difference in expression levels.

RESULTS

Cholesteatoma stroma expressed significantly more MMP-1 protein than did deep meatal skin stroma (p = 0.04). MMP-1 was localized to stromal fibroblasts. There was no difference in the epidermal expression levels of the two tissue types (p = 0.42). The reverse transcriptase polymerase chain reaction showed expression at the messenger ribonucleic acid size of MMP-1 (262 base pair) in all cholesteatoma specimens examined. One deep meatal skin specimen showed a weak signal; no signal was seen in the other specimens.

CONCLUSIONS

MMP-1 is overexpressed by the stromal fibroblasts present in cholesteatoma as compared with deep meatal skin. It is possible that these cells rather than the keratinocytes are responsible for bone destruction in this disease.

Effects of extracellular calcium on cholesteatoma migration and adhesion in vitro

Cholesteatoma matrix and tympanic epithelia share the unique property of en mass migratory locomotion in vitro. Although this migratory behavior is not well understood, it is thought to be a major contributor to the pathogenesis and pathophysiology of cholesteatoma disease. We have surmised that en mass migration depends on tight calcium-dependent intercellular and substrate cellular adhesions. The purpose of this investigation was to determine the effects of a diminished extracellular calcium level on cholesteatoma migration and adhesion. Cholesteatoma matrixes obtained intraoperatively from patients undergoing mastoidectomies for chronic ear disease were cut into small fragments and grown in culture. When cultured specimens were exposed to low-calcium medium (0.14 mmol/L calcium), a greater than 10-fold reduction in the rate of migration was observed when compared with control values (1.8 mmol/L calcium). This reduction of migration returned to normal within 48 hours after extracellular calcium was replenished. Substrate cellular adhesion was also significantly reduced when cholesteatoma cells were grown in low-calcium medium. These observations were further supported by histomorphologic findings. Our findings suggest that calcium-dependent intercellular and substrate cellular adhesions are essential for cholesteatoma migration and adhesion. These studies further our understanding of the pathophysiology of cholesteatoma disease and may provide clues on how to better treat patients with this disease.

Inhibition of Cholesteatoma Migration in vitro with all-Trans Retinoic Acid

Retinoids have recently become of interest to clinicians because of their ability to inhibit migration and proliferation of premalignant squamous cells while enhancing growth and proliferation of normal cells. An in vitro investigation was undertaken to determine whether retinoic acid exhibits similar inhibitory effects on cholesteatoma cells. Cholesteatoma specimens were obtained intraoperatively from 10 patients undergoing mastoidectomy or revision mastoidectomy for chronic ear disease. Cholesteatoma explant growth and en mass migration were observed daily, and topographic maps were constructed at various time intervals to quantify rate and direction of expiant migration in the presence or absence of all- trans retinoic acid. Before all- trans retinoic acid administration, explants migrated very rapidly (1 to 2 mm/day). A maximum threefold inhibition of migratory rate occurred, with explants exposed to 0.1 μmol/L retinoic acid when compared with controls. A sixfold maximum inhibition was observed at higher retinoic acid concentrations (5 μmol/L). On removal of all- trans retinoic acid, twofold and fourfold increases in migratory rates were observed. The direction of explant migration varied significantly for long periods of time and appeared not to be affected by retinoic acid. This investigation suggests that all- trans retinoic acid has an inhibitory effect on cholesteatoma cell migration. Retinoids may have a role in controlling cholesteatoma disease in the future.

A microanalytical study on human auditory ossicles in normal and pathological conditions

A microanalytical study of human auditory ossicles was performed in 11 normal adults, 13 infants, 13 foetuses, 7 middle ear cholesteatoma, 7 chronic otitis and 1 facial nerve schwannoma. Malleus and incus ossification is initiated in the foetal period, the Ca/P ratio reaching a value of 1.8-1.9 in the 29-gestation-week foetus and continues in the infant period until adult, except for the marginal area of the malleus head which appears mineralized in the infant. The normal Ca/P ratio for malleus is 2.10, and 2.19 for incus. In the stapes, mature Ca/P ratio values (2.11) appear in the footplate of the 23-gestation-weeks foetus. Stapes ossification continues in its head and crura, but never reaches malleus and incus values. We have confirmed that there is a relationship between Ca/P ratio and sulphur values in the ossification process; so when the first increases the second decreases. Finally, in our pathological material we have not found any significant alteration of Ca/P ratio, sulphur or other elements studied.

Third place--Resident Basic Science Award 1990. Interleukin 1 causing bone destruction in middle ear cholesteatoma

We previously reported the localization of interleukin 1 in the epithelial layer of human cholesteatomas. On the basis of other studies that showed interleukin 1 can stimulate fibroblasts and macrophages to produce collagenases and prostaglandins, we then proposed that interleukin 1 may play an important role in cholesteatoma-related bone resorption, also. Our immunocytochemical study involving more human cholesteatoma samples revealed the presence of interleukin 1 in bone cells and monocytes in the region of active bone destruction. In the present study, the effect of interleukin 1 on these cells found at the bone resorption site was examined. By radioimmunoassay, interleukin 1 was shown to stimulate the production of prostaglandin E2 by osteoblasts in vitro. Interleukin 1 also promoted the migration and multinucleation of bone marrow-derived monocytes. These osteoclast-like cells formed from monocytes contained tartrate-resistant acid phosphatase, and caused the resorption of the devitalized bone in vitro. Above findings suggest that interleukin 1 could cause the bone destruction in cholesteatomas, not only by stimulating the local bone cells, but also by recruiting monocytes for osteoclastic bone resorption.

The ultrastructure of lymphatic vessels in the human middle ear with cholesteatoma

Lymphatic vessels were few in the edematous portion of the cholesteatoma perimatrix of the human middle ear. But the lymphatic vessels contained mucus and consisted of degenerated endothelial cells. Edema of the perimatrix was considered to be caused by the degeneration of lymphatic vessels. Normal lymphatic vessels were found in the fibrous perimatrix, while macrophages infiltrated and phagocytosed cell debris. In addition, regenerating blood vessels were observed. Degeneration of connective tissue due to lymphatic edema and its repair were both present in the perimatrix. The degeneration of perimatrix was hypothesized to be caused by confined mucous epithelium behind the cholesteatoma matrix.

X-ray diffraction analysis of the auditory ossicles in chronic otitis

An X-ray diffraction analysis was carried out on 10 healthy mallei and incudes which were taken from cadavers and on 50 diseased mallei and incudes taken peroperatively from patients with atticoantral otitis. X-ray powder diagrams of normal ossicles were shown as a granular hydroxyapatite. In diseased ossicles, changes were found in the crystallinity of hydroxyapatite which can be divided into four groups: (i) with characteristics of a diagram of normal bones giving peaks of maximum intensity of a granular hydroxyapatite; (ii) with less hydroxyapatite crystallinity; (iii) characterized by the occurrence of an amorphous phase of bone; (iv) characterized by the absence of all types of crystallization. The occurrence of different phases of crystalline hydroxyapatite in various forms of atticoantral otitis does not depend on the type of pathological process, i.e., with or without cholesteatoma.

Pressure-induced bone resorption in the middle ear

Osteoclastic activity is seen in areas of bone resorption which are the result of experimental and human cholesteatoma. Many factors may induce osteoclasts, including transmitted pressure. The purpose of this study was to determine if transmitted pressure, in the absence of cholesteatoma, could cause localized bone resorption in the middle ear. Surgical grade silicone was implanted into the middle ear of gerbils without cholesteatoma. Bone resorption was observed only in areas where the implants exerted pressure on bone. It was estimated that pressures of 50 to 120 mm Hg (6.7 X 10(4) to 16 X 10(4) dynes/cm2) resulted in the induction of osteoclastic bone resorption.

Bone erosion in experimental cholesteatoma--the effects of implanted barriers

Mongolian gerbils and man are the only animals known to spontaneously develop bone-eroding aural cholesteatoma. The pathophysiology of bone erosion in cholesteatoma is controversial. The majority of investigators believe that direct contact between cholesteatoma and bone is necessary for erosion to occur. We implanted glass, Silastic, and micropore barriers in the middle ear between the advancing cholesteatoma and cochlea in 50 Mongolian gerbils. The barriers prevented direct contact of cholesteatoma and cochlea but did not inhibit bone erosion. We conclude that transmitted pressure may be responsible for bone erosion in aural cholesteatoma in gerbils.

Cell cooperation on bone resorption in chronic otitis media

Since collagen comprises over 90% of bone protein, collagenase appears to be a major factor in the resorption process of the organic matrix of bone. We have studied the mechanism of production of collagenase in cell cultures of rat skin fibroblasts and macrophages under various conditions. Production of collagenase by fibroblasts increased significantly with the addition of the conditioned medium obtained from the culture of endotoxin-activated rat peritoneal macrophages. This study concludes that the endotoxin-activated macrophages produced factor or factors which stimulate fibroblasts to produce collagenase.

Histology, pathogenesis, and treatment of cholesteatoma

Factors present in cholesteatoma connective tissue induce bone resorption in chronic otitis media. The presence of skin and its products appears to exacerbate the destructive influence of connective tissue. One exacerbating factor is pressure, shown in an animal model to increase bone resorption by influencing the subepithelial connective tissue. Consideration of pathogenic factors provides a rationale for modifications in the treatment of middle ear cholesteatoma.

Histochemical studies of cholesteatoma

Frozen sections of cholesteatomas were compared with postauricular and auditory canal skin and studied using histochemical methods. Several dehydrogenases, lysosomal enzymes and proteolytic activity were studied. Lactate and malate dehydrogenase activity was very strong in the epithelium and subepithelial tissue of cholesteatomas; no succinate dehydrogenase activity was observed. Esterase and acid phosphatase activity was prominent in cells of granulation tissue. Considerable proteolytic activity was observed in these cells and one specimen showed possible extracellular activity. Strong evidence of fat was found in the granulation tissue, particularly at the interface of granulation tissue and bone. In postauricular and auditory canal skin, enzyme activity was generally weaker; no evidence of fat was found. The findings are discussed in the light of other investigations on the importance of enzyme activity in bone destruction associated with cholesteatoma.

Cellular and subcellular events of bone resorption in human and experimental cholesteatoma: the role of osteoclasts

An ultrastructural study of the interface between aural cholesteatoma and adjacent bone was performed on specimens obtained from human and experimental gerbilline cholesteatoma. When an enlarging cholesteatoma contacted bone, a large number of monocytes and macrophages accumulated in the area of contact. The intervening middle ear mucosa degenerated and bone erosion occurred. Anatomic evidence is provided which indicates that bone erosion in both human and experimental cholesteatoma occurred as a result of the action of multinucleated osteoclasts. These osteoclasts had the ultrastructural appearance of normal osteoclasts with a well developed ruffled border and large numbers of mitochondria. These cells stained readily with acid phosphatase stains. Although many other mononuclear cells were seen in the vicinity of the eroded bone, only the multi-nucleated osteoclasts were associated with disappearance of the bone surface. Osteoclasts were commonly found in experimental cholesteatoma, but were infrequent in human cholesteatoma biopsies, presumable because patients undergoing cholesteatoma surgery ara often treated with topical installations of corticosteroids which inhibit osteoclasts.

Bone resorption in human cholesteatomas

In vivo studies of different aspects of bone resorption in human cholesteatomas are described in the immunodeficient “nude” mice. Cholesteatoma membranes were transplanted into the middle ear cavities of the mice. After 21–28 days, growth of cholesteatoma tissue could be demonstrated in 8 of 13 animals. In 7 of these 8 animals bone resorption of the labyrinthine wall and ossicles could be demonstrated; resorption with acute inflammation was found in only two animals. The cellular mechanism in relation to bone resorption is discussed.

Bone resorption in chronic otitis media. The role of cholesteatoma, a must or an adjunct?

The paper contains the results of light microscopical, electron microscopical and histochemical examinations of chronic otitis media, with and without cholesteatoma, with special focus on the problems regarding bone resorption. It is demonstrated that bone resorption takes place without the presence of cholesteatoma itself, even though the magnitude of resorption is higher in the cases with cholesteatoma. It is demonstrated that there is always a layer of subepithelial granulation tissue between the cholesteatoma membrane and the underlying bone. The picture in the resorbing zone is dominated by mononuclear histiocyte like cells, containing dense cytoplasmatic bodies, called lysosomes, and it is demonstrated that the marker enzyme for acid hydrolases, the acid phosphatase, is present in large quantities, both in the histiocytes, as well as spread along the bony surface. It is concluded that a possible mechanism for bone resorption is performed by the acid hydrolases, contained in the histiocytes, working at acid pH. It is noteworthy that the multinucleated osteoclast is not demonstrated in the resorbing margin of bone and that the picture is dominated by capillary proliferation, indicating that ischemia does not play a role in bone resorption. On the contrary, this is in the author's opinion caused by inflammation and hyperemia. The various factors influencing bone resorption in general and in chronic otitis media are discussed and a new model for studying cholesteatoma pathology in the middle ear is presented.

A contribution to the pathogenesis of cholesteatoma. A histochemical and ultrastructural study

In a histochemical and ultrastructural study the pathogenesis of cholesteatoma ostitis is analysed on human tissue. In the subepithelial layer there is evidence of an inflammatory reaction leading to proliferation of granulation tissue with bony invasion. Bony destruction is initiated by osteocytic osteolysis. In the case of cholesteatoma there is a combined action of extraosseous and osseous lysosomal enzymes. The pathological changes of the fibrillar elements suggest that the self-perpetuation of degeneration is maintained by a disturbance of fibrillogenesis. The causal pathogenesis of cholesteatoma formation is discussed as a function of a disturbance between cellular activity, extracellular matrix, and cellular surface.

Electron microscope study of bone lesion in cholesteatoma otitis

Biopsy specimens were obtained at ear surgery of patients with cholesteatoma otitis and were studied by electron microscopy. The osseous tissue decalcified in EDTA demonstrated degradation of collagen matrix as well as extensive degeneration of bone cells. The surface of the eroded bone was found to be in direct contact with the subepithelial connective tissue or the granulation, but not with the keratinizing squamous epithelium of matrix. These results indicate that the bone destruction by cholesteatoma is of non-osteoclastic type and lend support to the view that the keratinizing squamous epithelium do not participate in bone destruction. One the ultrastructural basis, the inflammatory process in the soft tissue adjacent to bone and extensive degeneration of bone cells are considered as cardinal factors for bone destruction in this disease.

Bone resorption in chronic otitis media

Bone resorption is an important aspect of chronic otitis media contributing to many complications of this disease. It is postulated that the mechanism of this localized destructive process is chemical in origin. Collagenase, lysosomal enzymes, prostaglandins, and other cell mediators are thought to induce bone resorption, but the site of action and cellular origin of these substances remains unclear. In this report, we demonstrate the location and attempt to delineate the cellular origin of two enzymes, collagenase and the lysosomal enzyme acid phosphatase in guinea pig temporal bones and human ossicles from ears containing chronic otitis media. Tissue localization of these enzymes identifies sites of active bone resorption and demonstrates the cells initiating this process. Using immunohistochemical and immunocytochemical techniques, collagenase was seen surrounding mononuclear inflammatory cells of granulation tissue at bone resorbing margins and at the periphery of osteocyte lacunae adjacent to resorbing areas. Electron microscopic data suggests that collagenase is an extracellular enzyme foun at the periphery of osteocytes. In addition, abundant acid phosphatase activity was seen in the same cells that exhibited collagenase staining, lending credence to the destructive function of these cells. The chronic inflammatory reaction found in chronic otitis media appears to activate bone destruction through the dynamic activity of mononuclear inflammatory cells and stimulates bone cells to increase their destructive biochemical functions.

Pathology of the ossicular chain in various chronic middle ear diseases

In a collection of 1,100 operated ears, 426 of which had cholesteatoma and 674 had not, the various defects of the ossicular chain are described and related to the nature of the disease and the site of perforation. The analysis showed marked differences between the various diseases and in the frequency of the individual ossicular defects or combinations of defects. Defects of the head of the malleus and of the body of the incus were found exclusively in chiolesteatomas, most often those affecting the attic. Isolated defects of the malleus handle were most common in cholesteatoma of the parts tensa and in total perforations. Defects of the long process of the incus occurred in 74--88 per cent of cholesteatomatous diseases, defects of the stapedial arch in 47 per cent of ears with sinus cholesteatoma. In granulating otitis without cholesteatoma and in sequelae to otitis there was less ossicular pathology, and 57 per cent of these ears had an intact ossicular chain. Total or posterior perforations were associated with pathology of the ossicles more often than inferior or anterior perforations. All cases with destruction of the body of the incus and the head of the malleus showed squamous epithelium in close relation to the ossicular defect, indicating a marked--presumably enzymatic--influence by the squamous epithelium upon the bone resorption.

Localization of collagenase in human middle ear cholesteatoma

The process of connective tissue breakdown in chronic otitis media is described in the context of recent advances in our understanding of collagen degradation and bone resorption. The significance of the initial step in collagen breakdown, brought about by the action of a specific collagen dissolving enzyme is emphasized in terms of recent studies in other chronic inflammatory diseases characterized by connective tissue breakdown. Bone resorption, a characteristic feature of chronic otitis media, requires the breakdown of collagen, which comprises over 90 percent of bone protein. Evidence in support of collagenase in bone resorption from adjacent tissue (in this case, inflammatory connective tissue) would require identification of the enzyme in cells involved in the inflammatory process adjacent to the resorbing bone. Collagenase was found localized in frozen sections of canal wall skin, middle ear granulation and in cholesteatoma by a specific binding of the enzyme with an antiserum produced against purified human skin collagenase. The antigen antibody complex was labelled with fluorescein. Collagenase appeared in the subepithelial connective tissue of cholesteatoma, granulation tissue from the middle ear and the dermis of canal skin; but was not seen in the keratin layer, epithelium or the epidermal appendages. The enzyme appeared within certain fibroblasts, macrophages and endothelial cells of capillary buds. Collagenase enhanced by chronic inflammation attacks the intact collagen molecule, making it susceptible to further digestion by other proteases that are also products of inflammation. This process brings about resorption of connective tissue and bone.

Experimental aural cholesteatoma causing bone resorption

A series of experiments were carried out on 55 guinea pigs in four groups to study the conditions fostering bone resorbin epidermal cysts. The first group had free grafts of canal wall skin applied to the cochlea with and without talc application. The second group had canal skin flaps applied to the cochlea with and without subsequent talc application. The third group had talc applied either to the tympanic membrane or on the cochlea. The fourth group had a canal skin flap inserted into a mucosal pocket in the bulla. The animals were killed three to four months after surgery and the temporal bones were prepared for histology. Epidermal cysts were found at the cochlea in 8 of 55 animals. Cochlear fistulas were found in 6 of 55 animals. The fistulas were associated with epidermal cysts in three cases, otitis media in two cases, and talc granuloma in one case. These experiments show that migrating skin attached to a source of epithelium is capable of inducing bone resorption. Chronic foreign body granulomas and chronic sepsis are also capable of resorbing bone. These three conditions all produce a layer of undifferentiated connective tissue containing chronic inflammatory cells lying against the resorbing bone.

Bone resorption in chronic otitis media. A light-microscopical and histochemical investigation of acid phosphatase activity

As a continuation of our previous work, where we have demonstrated that in chronic otitis media the picture in the submucosa-bone marginal zone is dominated by capillary proliferation and occurrence of a mononuclear, histiocyte-like cell containing lysosome-like cytoplasmatic bodies, we now report the presence of considerable activity of acid phosphatase in close relation to the eroded bone. The activity was localized both extracellularly, spread along the bony surface, as well as intracellularly in mononuclear, histiocyte-like cells. The acid phosphatase is the "marker" enzyme for lysosomes, and cells with these lysosomes guarantee the presence of enzymatic activity capable of attacking bone collagen. It is difficult to avoid the conclusion that the lysosomes and their enzymes are directly involved in the processes of bone resorption.

Collagenase activity in epidermoid carcinoma of the oral cavity and larynx

Summary--Tumor invasion requires the breadkdown of the main structural protein, collagen. A series of fourteen epidermoid carcinomas of the larynx and oral cavity produced a collagen dissolving enzyme in vitro as demonstrated by the breakdown of 14C-labeled collagen. Oral cavity tumors showed greater activity than laryngeal carcinomas while both sites were more active than uninvolved mucosa from the same patients. Tumor associated collagenase activity, in common with previously described collagenases, can only be demonstrated in vitro and requires protein synthesis. Maximum tumor collagenase occurred at 24 hours in vitro and then declined as compared with the maximum collagenase at 72 hours in vitro produced by oral cavity mucosa. The 14 patients in our series were ranked in order of the collagenase activity of their tumors. At 18 months after the diagnosis, four of the six patients with the most active tumors were dead of cancer and one patient was alive with persistent cancer. High collagenase activity may be a factor in the clinical aggressiveness of epidermoid carcinomas of the head and neck.

The Surgical Management of Labyrinthine Fistulae in Chronic Otitis Media with Cholesteatoma

The author's series of 168 consecutive cases of chronic otitis media from the years 1965 to 1972 were reviewed with regard to the occurrence and management of pathological fistulae in the bony labyrinth. Fourteen cases (incidence 8.3%), of which nine involved only the semicircular canals and five involved primarily the cochlear wall occasionally associated with a semicircular canal fistula, were examined particularly in terms of postoperative sensorineural hearing loss following removal of cholesteatoma matrix from the fistula. The results indicated that the matrix can be removed with reasonable safety from most small semicircular canal fistulae. Only when the cholesteatoma matrix is firmly adherent to a large area of membranous semicircular canal is removal not recommended. When the cholesteatoma was removed from three cochlear fistulae, sensorineural hearing loss resulted. In two cases with cochlear fistula, hearing was preserved when the cholesteatoma matrix was not removed from the fistulized area. These results have been used to formulate guidelines for the surgical management of pathological fistulae of the bony labyrinth.