Pulmonary cytology in paracoccidioidomycosis

Paracoccidioidomycosis caused by the fungus Paracoccidioides brasiliensis is a common endemic deep mycosis in Brazil and other Latin American countries; the lungs are frequently involved with suppurative and granulomatous inflammation. With the aim of using pulmonary cytology as a diagnostic tool in paracoccidioidomycosis, the cytologic findings in 127 sputa, 4 bronchial washings and 2 bronchial aspirates from 45 patients with the mycosis were reviewed. Smears from all samples were stained by the Shorr and Leishmann techniques. Cell-block preparations stained with hematoxylin and eosin and by the Gomori-Grocott method were available from 115 samples. Most samples (55%) were purulent, 30% were hemorrhagic and 17% were mucous. Polymorphonuclear neutrophils, macrophages and multinucleated giant cells were observed in all cases. P. brasiliensis was identified in samples from 95.5% of the patients, more frequently in the cell-block preparations (93%) than in the smears (57.7%), probably as the consequence of the application of the Gomori-Grocott stain to the former. Epithelioid cells were present in 62.2% and squamous metaplasia of the respiratory epithelium in 51.1% of cases. Cytology of pulmonary samples proved to be a useful diagnostic method for the detection of lung involvement by paracoccidioidomycosis in humans. The accuracy of the method increased with the number of samples examined from each patient.     

Interpreting microbiopsies in cervical smears. A cytohistologic approach

OBJECTIVE: To assess interobserver variation in the diagnosis of thick tissue specimens (microbiopsies) in cytology smears and histologic sections taken from them, to evaluate the applicability of MIB-1 in histologic sections from microbiopsies and to evaluate whether processing microbiopsies in inconclusive smears has additional diagnostic value. STUDY DESIGN: Cytologic smears were selected in which there were diagnostic disagreements between pathologists and cytologists and microbiopsies were present. Interobserver variation among three pathologists and three cytologists in the diagnosis of these microbiopsies was investigated. The smears were processed for histologic sections, and interobserver variation between pathologist diagnoses were analyzed. An additional histologic slide stained for MIB-1 was used for consensus diagnosis. The consensus diagnosis was compared with available follow-up and its sensitivity and specificity determined. The value of applying the microbiopsy technique in slides diagnosed as inadequate or atypical squamous cells of undetermined significance (ASCUS) was analysed. RESULTS: From a series of 62,334 cervical smears, 49 with microbiopsies were selected. It was possible to derive histologic slides from 38 cases. Interobserver variability in the diagnosis of microbiopsies and histologic sections from them was moderate--kappa = .44 (SE = .06) and kappa = .44 (SE = .09), respectively. In the consensus meeting for all cases, a conclusive diagnosis was reached. The Pearson correlation coefficient between the consensus diagnosis and MIB-1 staining was r = .62. The sensitivity of the consensus diagnosis for the follow-up diagnosis was 71% and the specificity 60%. Diagnosis on approximately 50% of slides diagnosed as inadequate or ASCUS could be made. CONCLUSION: The histotechnical workup of microbiopsies is not difficult; however, their diagnosis can be a problem. Adequate diagnostic criteria are not available. Aided by MIB-1 staining, histologic sections from microbiopsies can be diagnosed, and the diagnoses correlated with follow-up in most cases. Processing of microbiopsies in smears with an inconclusive cytologic diagnosis or a diagnosis of ASCUS allowed correct diagnosis in 50% of cases in this study.     

Adherence and intracellular parasitism of Paracoccidioides brasiliensis in Vero cells

Paracoccidioides brasiliensis is a dimorphic fungus known to produce invasive systemic disease in humans. The 43-kDa glycoprotein of P. brasiliensis is the major diagnostic antigen of paracoccidioidomycosis and may act as a virulence factor, since it is a receptor for laminin.Very little is known about early interactions between this fungus and the host cells, so we developed in vitro a model system employing cultured mammalian cells (Vero cells), in order to investigate the factors and virulence mechanisms of P.brasiliensis related to the adhesion and invasion process. We found that there is a permanent interaction after 30 min of contact between the fungus and the cells. The yeasts multiply in the cells for between 5 and 24 h. Different strains of P. brasiliensis were compared, and strain 18 (high virulence) was the most strongly adherent, followed by strain 113 (virulent), 265 (considered of low virulence) and 113M (mutant obtained by ultraviolet radiation, deficient in gp43). P. brasiliensis adhered to the epithelial cells by a narrow tube, while depressions were noticed in the cell surface, suggesting an active cavitation process. An inhibition assay was performed and it was verified that anti-gp43 serum and a pool of sera from individuals with paracoccidioidomycosis were able to inhibit the adhesion of P. brasiliensis to the Vero cells. Glycoprotein 43 (gp43) antiserum abolished 85% of the binding activity of P. brasiliensis. This fungus can also invade the Vero cells, and intraepithelial parasitism could be an escape mechanism in paracoccidioidomycosis.     

Evaluation of DNA polymorphisms amplified by arbitrary primers (RAPD) as genetically associated elements to differentiate virulent and non-virulent Paracoccidioides brasiliensis isolates

Randomly amplified polymorphic DNA (RAPD) analysis of 35 Paracoccidioides brasiliensis isolates was carried out to evaluate the correlation of RAPD profiles with the virulence degree or the type of the clinical manifestations of human paracoccidioidomycosis. The dendrogram presented two main groups sharing 64% genetic similarity. Group A included two isolates from patients with chronic paracoccidioidomycosis; group B comprised the following isolates showing 65% similarity: two non-virulent, six attenuated, five virulent, eight from patients with chronic paracoccidioidomycosis and two from patients with acute paracoccidioidomycosis. The virulent Pb18 isolate and six attenuated or non-virulent samples derived from it were genetically indistinguishable (100% of similarity). Thus, in our study, RAPD patterns could not discriminate among 35 P. brasiliensis isolates according to their differences either in the degree of virulence or in the type of the clinical manifestation of this fungal infection.     

Earliest detection of oral cancer using non-invasive brush biopsy including DNA-image-cytometry: report on four cases.

OBJECTIVE: We describe four patients presenting early oral cancers, detected cytologically on non-invasive brush biopsies including DNA-image cytometry as an adjunctive method before histology on scalpel biopsies confirmed the evidence of malignancy. METHODS: Brush biopsies were performed and smears thereof investigated cytologically. After Feulgen restaining, DNA-measurements were performed using a DNA-Image-Cytometer. CASE REPORTS: Oral squamous cell carcinomas were diagnosed cytologically in macroscopically suspicious lesions and malignancy confirmed by DNA-cytometry. The initially performed scalpel biopsies did neither supply evidence of oral cancer nor of severe dysplasia. After at least one to 15 months the occurrence of cancer was finally proven histologically on a second scalpel biopsy each (three microinvasive and one in situ carcinoma). CONCLUSION: Non-invasive brush biopsies are a suitable instrument for early cytologic detection of cancer of the mouth. DNA-image-cytometry, as an adjunctive method, can be used to confirm the cytologic diagnosis or suspicion of cancer in patients with doubtful lesions (dysplasias). DNA-aneuploidy is a marker for (prospective) malignancy in smears of the oral cavity, which may detect malignancy months prior to histology. In future this method could be used as a mass screening tool in dentists practice.     

Quantitative cytomorphologic analyses of Papanicolaou-stained smears from oral lichen planus

OBJECTIVE: To apply quantitative techniques to cytologic smears in order to improve the diagnostic sensitivity of cytology in the detection of malignant change in the oral cavity. STUDY DESIGN: Eighty-two patients with lesions of oral lichen planus were investigated. A total of 247 Papanicolaou-stained buccal smears underwent nuclear and cytoplasmic area measurements using a TV image analyzer. RESULTS: The cytomorphologic results of this study suggest that lesions of oral lichen planus contain smaller cells and nuclei than those observed in clinically normal oral mucosal smears. There was a statistically significant reduction in nuclear area (P < .001) and cytoplasmic area (P < .05) for the oral lichen planus smears. CONCLUSION: The TV image analysis system could provide a valuable method of quantifying cell changes in oral smears collected from oral mucosa as a method of monitoring lesions of oral lichen planus.     

HER-2/neu evaluation by fluorescence in situ hybridization on destained cytologic smears from primary and metastatic breast cancer

OBJECTIVE: To evaluate HER-2/neu amplification by fluorescence in situ hybridization (FISH) (HER-2/neu by FISH) on archival cytologic smears stained with May-Grünwald-Giemsa (MGG) stain. STUDY DESIGN: Cytologic specimens from 69 breast cancer lesions (48 primary and 21 metastatic), stained with MGG stain for routine diagnostic cytology, were destained and subjected to HER-2/neu by FISH. Fifteen of the 69 samples were also evaluated by FISH on paired fresh smears. RESULTS: HER-2/neu by FISH was successfully assayed in 25 of the 48 primary tumors and in 15 of the 21 metastatic lesions, corresponding to an overall feasibility of 58%. These cases had been archived between 1 month and 10 years prior to FISH analysis. Eight of the 25 primary and 5 of the 15 metastatic tumors were amplified. In 15 of the 40 evaluable cases, HER-2/neu was also assessed on the corresponding fresh smears: 8 tumors were amplified and 7 unamplified on both destained MGG and fresh smears. CONCLUSION: HER-2/neu can be detected by FISH on routinely MGG-stained cytologic slides. This approach allows HER-2/neu evaluation whenever histologic sections or fresh cytologic material are not available. In these cases, HER-2/neu assessment on destained cytologic smears plays a role in the selection of targeted therapy.     

Basic and 'special' stains for plastic sections in bone marrow histopathology, with special reference to May-Grünwald Giemsa and enzyme histochemistry

A battery of morphological, histochemical, and enzyme histochemical stains have been experimented on semithin sections of glycol-methacrylate-embedded bone marrow biopsies. We have been able to reproduce on sections the typical 'Romanowsky effect' which characterizes May-Grünwald Giemsa-stained smears of bone marrow or peripheral blood. This appears to be of critical importance for proper routine morphological evaluation of bone marrow biopsies. Conventional histochemical stains, and the enzyme histochemistry reactions that are most useful and widely used in the study of marrow aspiration smears have been successfully applied to plastic sections: in this way the evaluation of the cytochemical profiles of marrow diseases, especially leukemias, may be included in the histopathologist's diagnostic approach, with the additional advantage of preserving the architecture of the tissue and the relationship between haemapoietic cells and stromal components.     

Cytologic features of subependymal giant cell astrocytom: a review of 7 cases

OBJECTIVE: To describe the cytologic features of subependymal giant cell astrocytoma (SEGA) on smears and analyze cytomorphologic parameters that may help in reaching the diagnosis of SEGA. STUDY DESIGN: Cytologic smears of 7 cases of SEGA were reviewed and graded semi-quantitatively for 11 cytologic features: clustering, cytoplasmic fibrillary processes (fibrillarity), cellularity, small prominent nudcleoli, binucleation or multinucleation, "strap cells", spindle-shaped cells, mitoses, intranuclear inclusions, nuclear atypia and perivascular palisading/pseudorosettes. Corresponding histologic sections were also reviewed. RESULTS: The study included 5 male and 2 female patients with an average age of 8.3 years (range, 3-16) at surgery. Cytologic examination revealed loosely cohesive clusters of large cells possessing round to oval nuclei with no or minimal atypia; fine, evenly distributed chromatin; and abundant eosinophilic cytoplasm enmeshed in abundant thin, hairlike processes. Predominant features included hypercellularity, cell clustering, and fibrillarity. Binucleation or multinucleation; small, prominent nucleoli; and strap cells were often seen. Although common in histologic sections, perivascular palisading/pseudorosettes and spindled astrocytic cells were rarely noted on smears. CONCLUSION: The cytologic features of SEGA are highly characteristic and thus are of great use in supporting a diagnosis of SEGA and in excluding mimics, primarily gemistocytic astrocytoma and ependymoma.     

Chronic murine paracoccidioidomycosis: effect of ketoconazole on clearance of Paracoccidioides brasiliensis and immune response

In a murine model of chronic pulmonary and disseminated paracoccidioidomycosis, ketoconazole (100 mg kg-1 in 0.3% agar) given by gavage twice daily for 1 or 2 months enabled all mice to clear disseminated Paracoccidioides brasiliensis from the spleen. Clearance of P. brasiliensis from the lungs was more difficult, and was achieved in 60% of the mice treated for 2 months. Sera from agar-treated control mice at days 77 and 103 post-infection demonstrated precipitating antibodies to P. brasiliensis antigens, but sera from ketoconazole-treated mice were precipitin-negative, indicating a favorable prognosis. Delayed hypersensitivity reactions to P. brasiliensis antigens in ketoconazole-treated mice were not significantly greater than in controls; consequently this test correlated less well with response than levels of serum antibody. This is the first use of this animal model of paracoccidioidomycosis to study the effect of antifungal drug protocols on the resolution of the disease. It also demonstrates the utility of this model in addressing clinically relevant questions about this disease and its treatment.     

Diagnostic value of nucleolar organizer regions (AgNORs) in brush biopsies of suspicious lesions of the oral cavity.

OBJECTIVE: The aim of this retrospective study was to report on the diagnostic accuracy of AgNOR-analysis as an adjunctive diagnostic tool of conventional oral exfoliative cytology taken from suspicious lesions in our clinic. STUDY DESIGN: Cytological diagnoses obtained from brush biopsies of macroscopically suspicious lesions of the oral mucosa from 75 patients (final diagnoses: 53 histologically proven squamous cell carcinomas, 11 leukoplakias and other inflammatory oral lesions) and from 11 patients with normal mucosa as a negative control group were compared with histological and/or clinical follow-ups. Five smears were doubtful and seven suspicious for tumor cells in the cytologic report. Number of AgNOR's were counted in 100 squamous epithelial cell-nuclei per slide after silver-restaining. RESULTS: Sensitivity of our cytological diagnosis alone on oral smears for the detection of squamous carcinomas was 92.5%, specificity 100%, positive predictive value was 100% and negative 84.6%. The best cut-off value of the mean number of AgNOR dots per nucleus distinguishing benign from malignant cells was 4.8. The percentage of nuclei with more than three AgNORs had a cut-off level of 70%. Applying these methods to twelve doubtful or suspicious cytological diagnoses we were able to correctly establish the diagnosis of malignancy in ten cases of histologically proven cancers and to reveal benignity in two histologically proven cases. Thus we achieved a positive and negative predictive value of 100% each. CONCLUSIONS: Smears from brushings of visible oral lesions, if clinically considered as suspicious for cancer, are an easily practicable, non-invasive, painless, safe and accurate screening method for detection of oral cancerous lesions. We conclude that AgNOR-analysis may be a useful adjunct to other methods in routine cytological diagnosis of oral cancer that can help to solve cytologically suspicious or doubtful cases.     

Robinson cytologic grading in invasive ductal carcinoma of the breast: correlation with E-cadherin and alpha-, beta- and gamma-catenin expression and regional lymph node metastasis

OBJECTIVE: To correlate the cytologic grade of breast carcinoma with the expression of E-cadherin/catenin system molecules and the presence of metastasis in regional lymph nodes. STUDY DESIGN: Aspirate smears were examined together with histologic sections from the corresponding neoplasms taken from 100 patients with invasive ductal carcinoma. In 50 cases, > or = 1 metastatic nodes were identified. Cytologic grading of the smears was performed using the Robinson method. Immunohistochemical expression of E-cadherin and of alpha-, beta- and gamma-catenin was studied. RESULTS: A statistically significant relationship was observed between E-cadherin/catenin expression and cytologic grade (p < 0.0005). This association was particularly relevant to the cell dissociation parameter (p < 0.0005). CONCLUSION: The cytological grade established in preoperative studies may provide relevant information on the aggressiveness of invasive ductal carcinoma and its tendency to produce regional metastasis. This finding could be particularly useful in cases of breast carcinoma in which neoadjuvant therapy is the method of choice.     

A cytologic perspective on meibomian gland carcinoma

OBJECTIVE: To reevaluate and reestablish the reproducible diagnostic cytomorphologic features of meibomian gland carcinoma (MGCA), demonstrating the importance of fine needle aspiration cytology (FNAC) in eyelid lesions and leading to better management of the tumor. STUDY DESIGN: Cytologic smears ofpreviously diagnosed cases of MGCA over a 3-year period were collected, along with their histopathology reports. The cytomorphology of the histopathologically proven cases were reevaluated in greater detail. The cytologic smears were stained with Leishman-Giemsa cocktail and Papanicolaou stain, and the histopathologic sections were stained with hematoxylin-eosin. Special stains and immunohistochemical stains were applied as required. RESULTS: Of the 19 cases, 3 diagnosed as MGCA on cytologic examination were reported as basal cell carcinoma on histopathology. On reevaluation of the cytologic smears, in addition to the regular characteristic features of MGCA, interesting findings such as an isolated dispersed cell population in a bubbly background, signet ring cells, pseudo-mucin cell balls, giant cell reaction and hyaline-like round bodies were observed. CONCLUSION: This study emphasizes the cytomorphologic features of MGCA in addition to those described in the literature, which could be of a great help in its diagnosis. Further, it emphasizes the importance of FNAC in the diagnosis of MGCA.     

Fibromatosis colli in infants. A cytologic study of eight cases

OBJECTIVE: To review eight cases of fibromatosis colli and assess their cytomorphologic features. STUDY DESIGN: Cytologic smears from eight patients diagnosed as having fibromatosis colli on fine needle aspiration cytology were reviewed. RESULTS: Cytologic features of fibromatosis colli are bland-appearing fibroblasts and degenerative atrophic skeletal muscle in a clean background. Besides these, we found a large number of muscle giant cells; numerous bland, bare nuclei; and parallel clusters of fibroblasts. Collagen was seen in all cases. CONCLUSION: A confirmatory, noninvasive diagnosis of fibromatosis colli can be made by fine needle aspiration cytology alone; invasive diagnostic and therapeutic measures are best avoided. Excision biopsy may not be necessary and should be reserved for cases with a strong clinicopathologic suspicion of malignancy.     

Evaluation of polymerase chain reaction for the detection of Paracoccidioides brasiliensis DNA on serum samples from patients with paracoccidioidomycosis

The aim of this study was to demonstrate the DNA of Paracoccidioides brasiliensis in human serum samples of patients with paracoccidioidomycosis using the polymerase chain reaction (PCR). The diagnosis of paracoccidioidomycosis (PCM) was defined by microscopic observation of the fungus on direct exam or histopathology, culture, and serological positivity. DNA from serum of 33 patients with PCM was extracted and submitted to nested-PCR using primers from the gp 43 gene. Only one sample was positive on nested-PCR. We conclude that the prevalence of fungemia in patients with different clinical forms of PCM is low, limiting the use of serum DNA detection as an alternative diagnostic tool.     

Contribution of exfoliative cytology to the diagnosis of laryngeal lesions

OBJECTIVE: To estimate the diagnostic accuracy and reliability of exfoliative laryngeal cytology. STUDY DESIGN: Over three years (1996-1999) cytologic smears were obtained from clinically suspicious laryngeal lesions during laryngoscopy in a total of 31 selected patients (28 males and 3 females with an age range from 28-90 years). The cytologic diagnoses were analyzed and correlated with the histologic and final clinical diagnoses in 17 and 14 cases, respectively. Cytologic identification of the exact histologic type of the lesion was evaluated in 17 patients from whom both cytologic smears and biopsy material were obtained. RESULTS: The overall specificity was 100%, with no false positive diagnoses. The overall sensitivity was 93.3%, with one false negative cytologic diagnosis, in a case of non-Hodgkin's lymphoma. Cytohistologic correlation showed complete agreement between cytologic and histologic diagnoses in five of six benign lesions, in four cases of dysplasia and in six cases of squamous cell carcinoma. The overall diagnostic accuracy of cytology was 96.7% CONCLUSION: Exfoliative cytology by the smear technique is a reliable and accurate method in clinically suspected laryngeal lesions. Moreover, exfoliative cytology may be applied as the only alternative diagnostic method, especially in elderly patients with coexistent cardiorespiratory problems, when biopsy is not advisable or indicated.     

Detection of gp43 of Paracoccidioides brasiliensis by the loop-mediated isothermal amplification (LAMP) method

Paracoccidioidomycosis is a deep mycosis caused by the thermo-dependent dimorphic fungus Paracoccidioides brasiliensis and is prevalent in Latin American countries. We detected the species specific gp43 gene of P. brasiliensis by loop-mediated isothermal amplification (LAMP) in 22 clinical and seven armadillo-derived isolates. The amplified DNA appeared as a ladder with a specific banding pattern. The advantage of the LAMP method is speed; only 3 h were necessary for identification of the organism and diagnosis of the disease. We were also able to obtain positive results from DNA extracted from a paraffin-embedded tissue sample of paracoccidioidomycosis, suggesting that this method may achieve clinical application in the near future.     

Expression of p16INK4A in Pap smears containing atypical glandular cells from the uterine cervix

OBJECTIVE: To verify one of the diagnostic dilemmas concerning atypical glandular cells (AGC) by immunocytochemical detection of p16INK4A (p16) applied to routine Pap smears with correlation of follow-up biopsies for improvement of cytologic diagnoses. STUDY DESIGN: The study included 36 Pap smears in AGC diagnostic categories, all of which were correlated histologically. The cytologic diagnoses of AGC were further classified according to the 2001 Bethesda System. All Pap smears were decolorized and immunostained with the primary anti-p16 antibody, clone E6H4. Immunoreactivity for p16 was correlated with histologic sections in a semiblind fashion. RESULTS: Of the 36 smears containing AGC, 22 (61%) were reclassified as general AGC and 14 (39%) as AGC--favor neoplasia. Follow-up biopsies revealed that 15 (42%) cervixes had no obvious abnormalities and that 21 (58%) cases had different cervical lesions. More than half the cases (19/36, 53%) of follow-up biopsies concerning AGC-containing smears represented significant lesions. There was a much higher proportion of significant lesions (13/14, 93%) in AGC--favor neoplasia than those (6/22, 27%) in general AGC cases. Fifteen of 36 (36%) AGC-containing cases were actually squamous abnormalities on follow-up biopsies. p16 Immunocytochemical stain was reactive in 22 (61%) of 36 smears, either weakly/sporadically (2 cases, 6%) or strongly positively (20 cases, 55%). Conversely, 14 (39%) of the smears were negative for p16 and displayed predominantly reactive changes. However, there was 1 case of high grade squamous intraepithelial lesion showing negative immunostaining for p16. From the view-point of clinical significance, this analysis was highly sensitive (sensitivity, 95%) and specific (specificity, 88%) and had favorable positive (90%) and negative (94%) predictive values. CONCLUSION: On the basis of both morphologic and immunostaining patterns, there was a clear association between strong p16 immunostaining of atypical cells in smears and the presence of significant lesions in the cervix except in 1 patient. Similarly, there was a clear association between lack of p16 expression and absence of cervical lesions. p16 Immunocytochemical stain can be applied successfully to conventional Pap smears and may serve as a useful biomarker in diagnoses of AGC-containing smears. This may offer a more objective parameter to help clarify this ambiguous area of gynecologic cytopathology.     

Cytologic and DNA cytometric diagnosis and therapy monitoring of squamous cell carcinoma in situ and malignant melanoma of the cornea and conjunctiva

OBJECTIVE: To investigate the diagnostic accuracy of exfoliative cytology of the cornea and conjunctiva and DNA image cytometry for quality control and monitoring of therapy for malignant neoplasms. STUDY DESIGN: Conjunctival or corneal smears from six cases clinically suspicious for malignant melanomas and eight suspicious for carcinomas in situ were investigated. Smears from 18 cases clinically nonsuspicious for neoplastic diseases served as negative controls. Repeated smears were obtained during and after local mitomycin C (MMC) therapy. RESULTS: In none of 18 nonsuspicious cases, cytology revealed abnormal cells. DNA cytometry showed nonaneuploidy in all of these. All smears from patients with histologically proven malignant melanomas (MM) and squamous cell carcinomas in situ revealed abnormal cells. Image cytometry demonstrated DNA aneuploidy in 66.6% of patients with MM and 80% with carcinoma. Sensitivity of cytology thus was 100% for both MM and carcinoma; specificity also was 100%. DNA measurements after MMC therapy revealed euploid polyploidization of nonneoplastic squamous cells. DNA cytometry provided an objective identification of tumor cell regression. CONCLUSION: Cytologic examination of corneal and conjunctival smears is a noninvasive tool with high diagnostic accuracy for detection of epithelial neoplasms. DNA image cytometry can serve for quality control and for objective monitoring of the effect of local chemotherapy.     

P53 Immunostaining As A Marker For Oral Cancer In Diagnostic Cytopathology-Preliminary Report

The expression of p53 in oral mucosal disorders is strongly associated with malignant disease. Smears from normal and malignant oral mucosa were investigated for the presence of p53 using CM1 polyclonal antibody against p53 protein. the expression of p53 in smears was compared with the expression of the marker in biopsies from these oral carcinomas. p53 was identified in eight smears from 12 biopsy positive oral cancers. It was not seen in smears from eight p53-negative oral cancers and 40 smears from normal oral mucosa. It is suggested that expression of p53 in smears from a clinically suspicious lesion may be of value in the diagnosis of oral carcinoma.