Nasal cuboidal metaplasia with dysplasia. Precursor to adenocarcinoma in wood-dust-exposed workers?

Dynamics of pre-shift and post-shift lung function parameters among wood workers in Ghana

Background

Diseases affecting the lungs and airways contribute significantly to the global burden of disease. The problem in low- and middle-income countries appears to be exacerbated by a shift in global manufacturing base to these countries and inadequate enforcement of environmental and safety standards. In Ghana, the potential adverse effects on respiratory function associated with occupational wood dust exposure have not been thoroughly investigated.

Methods

Sixty-four male sawmill workers and 64 non-woodworkers participated in this study. The concentration of wood dust exposure, prevalence and likelihood of association of respiratory symptoms with wood dust exposure and changes in pulmonary function test (PFT) parameters in association with wood dust exposure were determined from dust concentration measurements, symptoms questionnaire and lung function test parameters.

Results

Sawmill workers were exposed to inhalable dust concentration of 3.09 ± 0.04 mg/m3 but did not use respirators and engaged in personal grooming habits that are known to increase dust inhalation. The sawmill operators also showed higher prevalence and likelihoods of association with respiratory symptoms, a significant cross-shift decline in some PFT parameters and a shift towards a restrictive pattern of lung dysfunction by end of daily shift. The before-shift PFT parameters of woodworkers were comparable to those of non-woodworkers, indicating a lack of chronic effects of wood dust exposure.

Conclusions

Wood dust exposure at the study site was associated with acute respiratory symptoms and acute changes in some PFT parameters. This calls for institution and enforcement of workplace and environmental safety policies to minimise exposure at sawmill operating sites, and ultimately, decrease the burden of respiratory diseases.

Allergic and Nonallergic Rhinitis. Classification and Pathogenesis: Part II. Nonallergic Rhinitis

Part I of this review classified and defined the causes of chronic rhinitis, describing in detail the etiology and pathophysiology of allergic rhinitis. Part II focuses on the nonallergic (non-IgE) causes of chronic rhinitis, concentrating on their clinical presentations, differential characteristics, and known or speculative pathophysiology. A comprehensive understanding of the allergic and nonallergic conditions associated with symptomatic rhinitis should aid the clinician in the appropriate diagnosis and treatment of patients with chronic rhinitis.

Intestinal-type sinonasal adenocarcinomas: The road to molecular diagnosis and personalized treatment

BACKGROUND

Sinonasal intestinal-type adenocarcinomas (ITACs) are epithelial tumors of the nasal cavity and the paranasal sinuses, often related to professional exposure to organic dust, mainly wood or leather. It is a rare cancer. If resectable, surgery is the treatment of choice. Postoperative radiotherapy is often indicated to increase local control. Systemic treatment (chemotherapy, targeted agents, or immunotherapy) of irresectable ITACs and/or metastasized disease is less standardized.

METHODS

Articles on ITAC histopathology, molecular profile, and current treatment options of this specific tumor were identified and reviewed, using the electronic databases Pubmed, Medline, Cochrane, and Web of Science.

RESULTS

This article reviews what is currently known on the histopathology, tumorigenesis, molecular characteristics, and standardized treatment options of ITAC.

CONCLUSION

More translational research is needed to identify druggable targets that may lead to a personalized treatment plan in order to improve long-term outcome in patients with locally advanced and/or metastasized ITAC. © 2016 Wiley Periodicals, Inc. Head Neck 38: First-1570, 2016.

Nasal Cavity and Paranasal Sinuses

The nasal cavity and paranasal sinuses occupy the top of the upper respiratory tract and form pneumatic spaces connected with the atmosphere. They are located immediately beneath the base of the cranium, where crucial vital structures are harbored. From this region, very much exposed to airborne agents, arise some of the more complex and rare benign and malignant lesions seen in humans, whose difficulties in interpretation make this remarkable territory one of the most challenging in the practice of surgical pathology.

Contents of this chapter cover inflammations and infections, polyps and pseudotumors, fungal and midfacial destructive granulomatous lesions, as well as benign, borderline, and malignant neoplasms. Among the neoplasms, emphasis is made on those entities characteristic or even unique for the sinonasal region, such as Schneiderian papillomas, glomangiopericytoma, intestinal- and non-intestinal-type adenocarcinomas, olfactory neuroblastoma, nasal-type NK-/T-cell lymphoma, and teratocarcinosarcoma. Moreover, recently recognized entities involving this territory, i.e., HPV-related non-keratinizing carcinoma, NUT carcinoma, and SMARCB1-deficient basaloid carcinoma, are also discussed in the light of their specific molecular findings. Furthermore, the text is accompanied by numerous classical and recent references, several tables, and 100 illustrations.

Chondroid chordoma and nasal adenocarcinoma: an exceptional association

Collision tumors are exceptional, associating two independent tumoral contingents. We report a case of an association of two rare tumors: sinonasal adenocarcinoma and chondroid chordoma. Initially, only adenocarcinoma was diagnosed. The treatment consisted of endoscopic endonasal surgery followed by conventional radiotherapy. After 18 months, a local recurrence was diagnosed after a facial trauma, but the true histology was difficult to assess. The tumor was dual, associating adenocarcinoma and chondroid chordoma, with atypical localization in the ethmoid. Further evolution was particularly aggressive. We discuss the key points of this observation.

Benign lesions in mucosa adjacent to intestinal-type sinonasal adenocarcinoma

Occupational exposure to wood dust is a strong risk factor for the development of intestinal-type sinonasal adenocarcinoma (ITAC); however, knowledge on possible precursor lesions or biomarkers is limited. Fifty-one samples of tumor-adjacent mucosa and 19 control samples of mucosa from the unaffected fossa of ITAC patients were evaluated for histological changes and p53 protein expression. Mild dysplasia was observed in 14%, cuboidal metaplasia in 57%, intestinal metaplasia in 8%, squamous metaplasia in 24%, and cylindrocellular hyperplasia in 53% of cases. P53 immunopositivity was generally weak occurring most frequently in squamous metaplasia. Wood dust etiology did not appear of influence on the histological changes, but p53 showed a tendency for higher positivity. Dysplasia adjacent to tumor was indicative of subsequent development of recurrence. In conclusion, precursor lesions do occur in mucosa adjacent to ITAC. This is clinically important, because it may justify the screening of high-risk individuals such as woodworkers.

Sinonasal carcinomas: recent advances in molecular and phenotypic characterization and their clinical implications

Sinonasal carcinomas are rare tumors with an aggressive clinical behaviour which frequently pose a number of problems regarding the interpretation of diagnostic findings and the treatment. In addition, in comparison with other malignancies of the head and neck region, an elevated fraction of sinonasal carcinomas can be attributed to occupational exposure. This review is focused on the recent advances in the molecular and phenotypic characterization of sinonasal carcinomas, and their possible implications for the interpretation of epidemiological data, as well as for the diagnosis and treatment of these rare malignancies. The increasing knowledge on their phenotypic and genotypic features is progressively leading to a refinement in diagnosis, especially for poorly differentiated and undifferentiated lesions, as well as to the identification of markers which can be potentially useful to identify the early phases of carcinogenesis, to detect subclinical disease, to predict the response to therapy, and finally, that may represent potential targets for alternative treatments.

A morphologic and immunohistochemical study of nasal mucosa in leatherworkers

BACKGROUND

The association between intestinal-type sinonasal adenocarcinoma and the occupational exposure to leather dusts has been widely documented, but the identification of precursor lesions in exposed workers has remained controversial. The purpose of this study was to investigate the histological changes and modifications in the phenotype of epithelial cells in nasal mucosa of leather workers.

METHODS

Biopsy specimens of the mucosa of the middle turbinate were obtained from 139 subjects who had been employed in leather factories for 10-48 years (median, 29 years). Tissue fragments were routinely processed for histological examination and immunostainings for cytokeratin 20, CDX-2, and MUC-2 were performed.

RESULTS

Regarding the surface epithelium, the most common histopathological finding was the presence of squamous metaplasia (64.7%), which was associated with mild to moderate dysplasia in 37 cases (41.1%), and goblet cell hyperplasia was identified in 30 biopsy specimens (21.6%). Positivity for MUC-2 was detected in goblet cells of 20 of the 30 samples with goblet cell hyperplasia (66.6%), whereas no immunostaining was observed for cytokeratin 20 and CDX-2. Presence of goblet cell hyperplasia was significantly associated with longer occupational exposure in leather tanning activities (p = 0.03). None of the alterations observed (squamous metaplasia, dysplasia, or goblet cell hyperplasia) showed correlation with smoking habits. Similarly, there was no correlation between squamous metaplasia with or without dysplasia and type and duration of occupational exposure.

CONCLUSION

Our data identify goblet cell hyperplasia as possible work-related alterations of nasal mucosa in leather workers. Additional investigations are needed to clarify the significance of these findings in the development of sinonasal intestinal-type carcinoma.

Chromosomal imbalances in wood dust-related adenocarcinomas of the inner nose and their associations with pathological parameters

Comparative genomic hybridization (CGH) was used to screen 42 wood dust-related sinonasal adenocarcinomas for chromosomal alterations. The tumour collection comprised 39 papillary-tubular cylinder cell adenocarcinomas (PTCCs; six cases G1, 23 G2, and ten G3), two alveolar goblet cell adenocarcinomas (AGCs), and one signet ring cell adenocarcinoma (SRC), according to the Kleinsasser and Schroeder classification. Copy number changes were detected in 41 tumours (97.6%). The one carcinoma without imbalances was a PTCC-G1. DNA gains were most frequently seen on chromosomes 12p (83%), 7q (74%), 8q (71%), and 20q (71%), 11q (61%), 22 (59%), and 1q (52%). Pronounced overrepresentations suggestive of high copy amplifications were detected on 8q (15 cases, 36%), 7q (six cases, 14%), 20q (five cases, 12%), 13q14 (three cases, 7%), 1q22, 5p, 12p and 20 (two cases, 5% each), and 2q24, 3q13, 3q22, 7p, 14q12, and 16q13 (one case, each 2%). Frequent chromosomal losses occurred at 5q (81%), 18q (76%), 4 (74%), 8p (61%), 9p (60%), 6q and 17p (52% each), and 3p, 13q, and 21 (50% each). There was a quantitative as well as a qualitative increase of alterations from PTCC-G1 to PTCC-G2 and finally PTCC-G3, confirming the usefulness of histopathological grading. While PTCC-G1 carried only a few alterations, namely gains on chromosomes 17 and 7 as well as losses of 4q and 13q, PTCC-G2 already carried many of the above-mentioned alterations, while PTCC-G3 showed significantly more gains of 7q, 8q, and 12p, and losses of 8p and 17p. Additionally, the latter subgroup was particularly prone to carry pronounced DNA gains. These data provide further evidence for a recurrent pattern of chromosomal imbalances in sinonasal adenocarcinomas and highlight distinct aberrations that are associated with tumour differentiation and progression.

Expression pattern of CK7, CK20, CDX-2, and villin in intestinal-type sinonasal adenocarcinoma

BACKGROUND

Intestinal-type sinonasal adenocarcinoma (ITAC) is an uncommon neoplasm, which resembles adenocarcinoma of the gastrointestinal tract. ITAC occurs sporadically or in association with occupational exposure to hardwood dust and other agents.

AIMS

To investigate the phenotype and possible pathogenetic mechanisms of primary sinonasal and nasopharyngeal adenocarcinomas by staining for cytokeratin 7 (CK7), CK20, CDX-2, and villin.

METHODS

Twelve sporadic sinonasal and nasopharyngeal adenocarcinomas were stained with monoclonal antibodies to CK7, CK20, CDX-2, and villin. The ITACs were classified as papillary, colonic, solid, mixed, or mucinous types.

RESULTS

The diagnosis of ITAC was confirmed in 10 cases: five were colonic type and five were papillary. One was a sinonasal papillary low grade adenocarcinoma, and one a papillary nasopharyngeal adenocarcinoma, and these tumours were CK7 positive, but CK20, CDX-2, and villin negative. All ITACs were positive for CK20, CDX-2, and villin, and six were CK7 positive. One ITAC had a focus of intestinal metaplasia away from the invasive carcinoma.

CONCLUSIONS

Sinonasal ITACs have a distinctive phenotype, with all cases expressing CK20, CDX-2, and villin. Most ITACs also express CK7, although a proportion of tumours are CK7 negative. ITAC seems to be preceded by intestinal metaplasia of the respiratory mucosa, which is accompanied by a switch to an intestinal phenotype. Although ITACs are morphologically similar, differences in cytokeratin expression patterns suggest two distinct types. The expression pattern of CK7, CK20, CDX-2, and villin positive may be useful in separating these tumours from other non-ITAC adenocarcinomas of the sinonasal tract and nasopharynx.

[Nasal sinus carcinoma after wood dust exposure. Morphological spectrum of 100 cases]

Sinonasal carcinomas are usually of the squamous cell or transitional cell type. Adenocarcinomas of the inner nose and the paranasal sinus correlate with exposure to wood dust. However, this is only true for adenocarcinomas of the intestinal type and not for salivary gland carcinomas or polymorphous low-grade adenocarcinomas. Of 160 cases with a history of wood dust exposure and malignant tumors of the inner nose, 134 were sinonasal adenocarcinomas of the intestinal type (SNAIT). In addition, there were 24 other carcinomas as well as 1 malignant melanoma and 1 malignant synovial tumor. The SNAIT showed various subtypes with great morphological similarities to colorectal adenocarcinomas (papillary tubular cylinder cell: 72.4%; alveolar goblet cell: 5.2%; signet ring cell: 3.7%; transitional type: 18.7%). Highly differentiated adenocarcinomas (G1) and mucinous adenocarcinomas were relatively frequent: they accounted for 23.1% and 29.1% of the 134 SNAIT, respectively. Apart from wood dust, wood additives are discussed as a carcinogenic factor. With the development of SNAIT, a metaplasia-dysplasia-carcinoma in situ sequence is probable. If the clinical course shows few symptoms, the first manifestation of such a tumor often occurs in an advanced stage.

Evidence of p53 immunohistochemical overexpression in ethmoidal mucosa of woodworkers

A high risk of neoplastic transformation of nasal and paranasal sinuses mucosa is related to the occupational exposure to wood dust, however no conclusive data have been reported up to now about morphological precursors of these tumors, mechanisms of carcinogenesis and role of p53 gene. Immunohistochemical overexpression of protein p53 (DO7 clone) by epithelial cells of ethmoidal mucosa was investigated on 60 woodworkers occupationally exposed for a minimum of 10 years, on 50 functional and/or esthetic nasal surgery patients (control group) and on 15 cases of intestinal-type adenocarcinoma, 10 of these involving subjects who had a longtime exposure to wood dust. In almost all the woodworkers (92%) the normal ciliated epithelium showed tracts of squamous metaplasia. The mean percentage of p53-positive cells in woodworkers and in controls was 28.6 and 7.97%, respectively, in metaplastic epithelium (P<0.001), 11.7 and 2.08% in ciliated epithelium (P<0.001), 12.46 and 1.03% (P<0.001) in the sero-mucous glands of the nasal stroma. Both in tracts of metaplastic epithelium and in those of ciliated epithelium, positive cells were distributed in basal and suprabasal layers. A high number of p53-positive cells was also observed in the normal ciliated epithelium close to the neoplastic cells, of intestinal-type adenocarcinomas affecting subjects with longtime exposure to wood dust. Moreover, a higher number of p53 positive neoplastic cells was showed by the cases occurring in occupationally exposed patients than by the others. The following conclusions can be drawn: (1) in the ethmoidal mucosa, a region at high risk of carcinogenesis in subjects exposed to wood dust, epithelial cells overexpress p53 protein, and this may be linked to the presence of p53 gene mutations; malignant transformation, as at other head and neck sites, may thus occur through this pathway; (2) the presence of p53 overexpression in sero-mucous glands is in keeping with the histogenesis of some tumors from these structures; (3) since tumors of nose and paranasal sinuses, mainly adenocarcinoma, are recognized as occupational neoplasias, immunohistochemical evaluation of p53, perhaps combined with molecular methods, could be the first step to detect subjects at high risk of carcinogenesis among woodworkers.

Study of ethmoidal mucosa in a population at occupational high risk of sinonasal adenocarcinoma

The occurrence of nasal adenocarcinomas was first described in 1965. Since 1988 these tumors have been accepted as an occupational disease for woodworkers in Italy. There are several underlying reasons why there is interest in studying the ways in which sinonasal adenocarcinomas occur. Often diagnosed at advanced stages of development because their symptoms are non-specific, these tumors are associated with a high mortality rate. A multidisciplinary study protocol was developed in this investigation. The aim was to identify the factors and conditions that promote sinonasal tumor growth in a population at risk due to occupational exposure to wood dust. Sixty-eight carpenters with a minimum of 10 years exposure to wood dust were studied. The control group comprised 81 volunteers. The patients underwent the following protocol: completion of a case report form, physical examination, evaluation of nasal cavity patency, clinical laboratory tests and histological study of the nasal mucosa. Our study provides significant evidence of the elevated incidence of pavimentous metaplasia in workers occupationally exposed to wood dust. In addition, it underscores a significant deficit of immunoglobulin A in such workers compared to the controls. However, we did not find, as reported elsewhere in the literature, a statistically significant difference between cases and controls as regards nasal symptoms and hyperemia of the nasal mucosa. Our study showed that, even in the absence of evident sinonasal lesions, it is still possible to determine an increased incidence of morphofunctional changes in subjects occupationally exposed to wood dust. Our findings may lead to the identification of occupational groups prone to elevated risk of the disease.

Health risks associated with inhaled nasal toxicants

Health risks of inhaled nasal toxicants were reviewed with emphasis on chemically induced nasal lesions in humans, sensory irritation, olfactory and trigeminal nerve toxicity, nasal immunopathology and carcinogenesis, nasal responses to chemical mixtures, in vitro models, and nasal dosimetry- and metabolism-based extrapolation of nasal data in animals to humans. Conspicuous findings in humans are the effects of outdoor air pollution on the nasal mucosa, and tobacco smoking as a risk factor for sinonasal squamous cell carcinoma. Objective methods in humans to discriminate between sensory irritation and olfactory stimulation and between adaptation and habituation have been introduced successfully, providing more relevant information than sensory irritation studies in animals. Against the background of chemoperception as a dominant window of the brain on the outside world, nasal neurotoxicology is rapidly developing, focusing on olfactory and trigeminal nerve toxicity. Better insight in the processes underlying neurogenic inflammation may increase our knowledge of the causes of the various chemical sensitivity syndromes. Nasal immunotoxicology is extremely complex, which is mainly due to the pivotal role of nasal lymphoid tissue in the defense of the middle ear, eye, and oral cavity against antigenic substances, and the important function of the nasal passages in brain drainage in rats. The crucial role of tissue damage and reactive epithelial hyperproliferation in nasal carcinogenesis has become overwhelmingly clear as demonstrated by the recently developed biologically based model for predicting formaldehyde nasal cancer risk in humans. The evidence of carcinogenicity of inhaled complex mixtures in experimental animals is very limited, while there is ample evidence that occupational exposure to mixtures such as wood, leather, or textile dust or chromium- and nickel-containing materials is associated with increased risk of nasal cancer. It is remarkable that these mixtures are aerosols, suggesting that their "particulate nature" may be a major factor in their potential to induce nasal cancer. Studies in rats have been conducted with defined mixtures of nasal irritants such as aldehydes, using a model for competitive agonism to predict the outcome of such mixed exposures. When exposure levels in a mixture of nasal cytotoxicants were equal to or below the "No-Observed-Adverse-Effect-Levels" (NOAELs) of the individual chemicals, neither additivity nor potentiation was found, indicating that the NOAEL of the "most risky chemical" in the mixture would also be the NOAEL of the mixture. In vitro models are increasingly being used to study mechanisms of nasal toxicity. However, considering the complexity of the nasal cavity and the many factors that contribute to nasal toxicity, it is unlikely that in vitro experiments ever will be substitutes for in vivo inhalation studies. It is widely recognized that a strategic approach should be available for the interpretation of nasal effects in experimental animals with regard to potential human health risk. Mapping of nasal lesions combined with airflow-driven dosimetry and knowledge about local metabolism is a solid basis for extrapolation of animal data to humans. However, more research is needed to better understand factors that determine the susceptibility of human and animal tissues to nasal toxicants, in particular nasal carcinogens.

Factors in the pathogenesis of tumors of the sphenoid and maxillary sinuses: a comparative study

OBJECTIVES/HYPOTHESIS

To explain the processes that lead to the development of tumors in the maxillary and sphenoid sinuses.

STUDY DESIGN

A 32-year review of the world's literature on neoplasms of these two sinuses and a randomized case-controlled study comparing the normal mucosal architecture of the maxillary to the sphenoid sinus.

METHODS

Analysis of a 32-year world literature review reporting series of cases of maxillary and sphenoid sinus tumors. Tumors were classified by histological type and separated into subgroups if an individual incidence rate was reported. Histomorphometry of normal maxillary and sphenoid sinus mucosa was performed in 14 randomly selected patients (10 sphenoid and 4 maxillary specimens). Specimens were fixed in 10% formalin, embedded in paraffin, and stained with periodic acid-Schiff (PAS) and hematoxylin. Histomorphometric analysis was performed with a Zeiss Axioscope light microscope (Carl Zeiss Inc., Thornwood, NY) mounted with a Hamamatsu (Hamamatsu Photonics, Tokyo, Japan) color-chilled 3 charge coupled device digital camera. The images were captured on a 17-inch Sony (Sony Corp., Tokyo, Japan) multiscan monitor and analyzed with a Samba 4000 Image Analysis Program (Samba Corp., Los Angeles, CA). Five random areas were selected from strips of epithelium removed from each sinus, and goblet and basal cell measurements were made at magnifications x 100 and x 400.

RESULTS

The literature review revealed that the number and variety of tumors in the maxillary sinus are much greater than those in the sphenoid. The incidence of metastatic lesions to each sinus is approximately equal. No recognized pattern of spread from any particular organ system could be determined. On histomorphometric study there were no statistically significant differences between the sinuses in the concentration of goblet cells, basal cells, or seromucinous glands.

CONCLUSIONS

Factors involved in the pathogenesis of tumors of the maxillary and sphenoid sinuses include differences in nasal physiology, embryology, morphology, and topography. There are no significant histological differences in the epithelium and submucous glands between the two sinuses to explain the dissimilar formation of neoplasms.

Carcinogenic response of the nasal cavity to inhaled chemical mixtures

Nasal cancers occur in experimental animals following chronic exposure to a wide range of inhaled chemicals. Although exposure to several of these chemicals is common in industrial as well as domestic environments, epidemiological studies have not provided convincing evidence that exposure to these chemicals individually is associated with nasal cancer in humans. The reverse seems to be true for inhalation of chemical mixtures. The evidence for nasal carcinogenicity of inhaled chemical mixtures in experimental animals is very limited, while there is ample evidence in humans that occupational exposure to certain chemical mixtures is associated with increased risk of nasal cancer. Examples of such (complex) chemical mixtures are wood dust, textile dust, chromium- and nickel-containing materials and leather dust. It is remarkable that these mixtures are aerosols, suggesting that a 'dusty working environment' may increase nasal cancer risk.

Wood dust and nasal cancer risk. A review of the evidence from North America

In this article, biomedical literature assessing risks of nasal cancer and nonmalignant nasal pathology among woodworkers in North America is reviewed in detail and contrasted with experience from Europe and elsewhere. Exceptionally high rates of nasal adenocarcinoma have occurred among European hardwood furniture workers, but the epidemiologic evidence documents a disparity in findings between North America and Europe. Cohort studies of American wood-dust-exposed groups do not reveal excesses of nasal cancer, and wood-dust associations from US and Canadian case-control studies of nasal cancer tend not to be strong and differ across studies. Quantitative wood-dust exposure data are generally unavailable, but general dose information in European studies suggests that the excess risk of nasal cancer is associated with high levels of exposure. There is also an inconsistent association between wood-dust exposure per se and mucostasis or nasal histologic changes, and the mucostasis/metaplasia/dysplasia route to nasal cancer is still an unverified hypothesis. Considering the totality of evidence on the risk of cancer in exposed workers, it appears that wood-dust-related nasal adenocarcinoma essentially can be eliminated in Europe and its occurrence prevented in the United States if wood-dust exposures do not exceed an 8-hour time-weighted average 5 mg/m3 standard.

Carcinogenic effects of wood dust: review and discussion

Occupational exposure to wood dust (alone or chemically treated) is associated with an increased risk of developing adenocarcinoma of the nasal cavity. The specific causative agents, i.e., wood dust alone (natural products), wood dust with additives used in the processing or manufacturing of wood products, and/or physical determinants of wood dust and the associated risk factors, are not known or understood. The strongest association of exposure to wood dust and development of nasal cancer is observed in those occupations where workers are exposed to hard wood dust and chemical additives are not used. The time between first occupational exposure to wood dust and the development of adenocarcinoma of the nasal cavity averages 40 years (range 7-70 years). The epidemiological data available are not sufficient to make a definitive assessment between wood dust exposure and increased risk for cancer other than nasal cancer. The toxicity, mutagenicity, and carcinogenicity of wood dust to laboratory animals or in vitro with animal or microbial cells have not been thoroughly studied. Thus there is no direct experimental evidence on the potential hazards of wood dust. Data are insufficient or lacking on 1) wood dust exposure levels in ambient air and worker's breathing zone, and the deposition in the nasal cavity; 2) hard vs. soft wood dusts; 3) particle size and shape; 4) chemical composition of wood dust and the extent of contamination with chemical additives; and 5) interaction between inhaled wood dust, chronic irritation, and tobacco smoking. These data are required so that one can understand the association between wood dust exposure and nasal cavity tumors, along with demographic differences in cancer rates, and to develop strategies for intervention and reduction of disease causing agents in order to reduce risk to wood industry workers.

Pollution: the nose and sinuses

The nose and sinuses are constantly exposed to the huge quantities of gases needed to maintain life. Not only is the human nose well-equipped to warm and humidify this inhaled air, but it is also uniquely able to clean much of it. Any material other than physiologic amounts of oxygen, nitrogen, carbon dioxide, and water that accompanies the airstream can be considered a pollutant, and this pollutant could potentially injure the individual. The following discussion will review the defense mechanisms that allow the nose and sinuses to protect the lower airways. The effects of pollutants on the respiratory mucosa will then be described, including some recent trends in those effects. These trends include specific population consequences of indoor and outdoor air pollution, and changes in risk for individuals in several occupations. Throughout these discussions, specific areas that would benefit from further research will be mentioned.

Preinvasive stages of adenocarcinoma of the nose after exposure to wood dust

The early stages of adenocarcinoma of the nose due to exposure to beech and oak wood dust show superficial preinvasive growth. The papillary and tubular structures of this "adenocarcinoma in situ" are identical with those of invasive adenocarcinomas. There are no indications that cuboid or squamous metaplasia precedes the development of this type of carcinoma.

Scanning electron microscopic study of nasopharyngeal carcinoma

The study has been carried out on biopsies taken from four patients affected by squamous cell carcinoma and four patients affected by undifferentiated carcinoma of nasopharyngeal type (UCNT). Three healthy volunteers have served as controls. All the specimens have been studied by SEM. The neoplastic conditions cause obvious alterations both in the mucosal surface and in the morphology of the cellular apex.

Cancer epidemiology of woodworking

The literature published between 1965 and 1989 on the cancer epidemiology of woodworking in furniture industries and carpentry shops in 17 countries is reviewed. Included are some unpublished data obtained through personal communication with epidemiologists or collected from doctoral dissertations. Of 5,785 cases with sino-nasal cancers, about 23% were found to be woodworkers. Dusty jobs, especially wood processing using high-speed machines, are mainly associated with the enhanced incidence of nasal adenocarcinomas. The latency periods of the latter tumors ranged from 7 to 69 years in five European countries. A variety of neoplasias of the respiratory, digestive, and urinary tracts as well as the hemopoietic and lymphatic systems, including Hodgkin's disease are reported to be significantly associated with occupational exposure to wood dust. These data suggest that the exposure to some types of wood dust might cause a systemic rather than local neoplastic disorder.

Adenocarcinomas of the inner nose after exposure to wood dust. Morphological findings and relationships between histopathology and clinical behavior in 79 cases

We present the results of light microscopic, available electron microscopic and immunohistochemical investigations of 79 adenocarcinomas occurring in the noses of wood workers following exposure to beechwood and oakwood dust. Three types of adenocarcinomas can be differentiated. The most frequently occurring form is the papillary tubular cylinder cell adenocarcinoma, while the mucus-producing alveolar goblet cell adenocarcinoma and signet ring cell adenocarcinoma are rarer types. Transitional stages suggest the common origin of these tumors from mucus-secreting cylinder cells of the respiratory epithelium. The grade of differentiation and the tumor type are definitely related to the prognosis of these tumors. Similar to the tumors of the gastrointestinal tract, electron microscopy and immunohistochemistry prove the existence of a number of various polypeptide hormones, the significance of which has not yet been clarified.