International Histological Classification Of Tumours Research Articles

SOLUBLE FORMS OF THE NKG2D RECEPTOR AND LIGAND NKG2DL1 IN PATIENTS WITH COLORECTAL CANCER

Relevance. Natural killer (NK) cells are considered to be effective cytotoxic cells of the tumor microenvironment, whose function is to effectively eliminate tumor cells. Their activation can occur when the NKG2D receptor interacts with the NKG2DL ligand expressed, for example, on tumor cells, which leads to the death of the latter. The aim of the study was a comparative study of the content of soluble forms of the sNKG2D receptor and its ligand sNKG2DL1 in the blood serum of healthy donors and patients with colorectal cancer (CRC), taking into account the clinical and morphological characteristics of the disease and prog-nosis. Material and methods. We examined 65 patients with CRC (32 women and 33 men), who were treated at the “National Medical Research Center of Oncology named after N.N. Blokhin” of the Ministry of Health of Russia aged (median 60 years) and 30 healthy donors (20 women and 10 men) aged (median 47 years). The clinical diagnosis in all patients was confirmed by the data of the morphological study of the tumor according to the Interna-tional Histological Classification of Tumors of the Digestive System (WHO, 2019), all had adenocarcinoma. The concentration of NKG2D and NKG2DL proteins was determined by ELISA in blood serum before treatment with Human B7-H3 Quantikine ELISA Kit reagents firm R&D (USA) in accordance with the manufacturer's instructions. The measurements were carried out on an automatic enzyme immunoassay analyzer BEP 2000 Advance (Siemens Healthcare Diagnostics, Germany). Statistical analysis of the obtained results was carried out using GraphPad Prizm v. 9. Overall survival analysis was performed by constructing survival curves using the Kaplan-Meier method. Results. In patients with colorectal cancer, a significant increase in the content of sNKG2DL in blood serum was found compared to the control group. sNKG2D concentrations did not differ between controls and CRC patients. No significant associations were found between the content of sNKG2D and sNKG2DL1 proteins in the blood serum of CRC patients and the main clinical and morphological characteristics of the disease. A decrease in the con-centration of sNKG2D was noted with the progression of the disease, and the highest content of sNKG2D was found in the localization of the tumor in the caecum. For the ligand sNKG2DL1, the opposite pattern was observed, namely, its lowest concentration in blood serum in tumors located in the caecum. For the ligand sNKG2DL1, the opposite pattern was observed, namely, its lowest concentration in blood serum in tumors located in the cae-cum. At the same time, the levels of sNKG2D and sNKG2DL1 in the control group directly and significantly correlated with each other (r=0.453; p=0.014), while no such pattern was found in the group of CRC patients (r=0.014; p=0.935). sNKG2DL1 concentrations are not a prognostic factor in CRC, while high levels of sNKG2D tended to lead to a favorable prognosis of the disease, which indirectly confirms the positive significance of tumor in-filtration by NK cells. Conclusions. The mechanisms of the relationship between CRC avoidance of immune surveillance and the expression of the sNKG2D receptor and the sNKG2DL ligand are discussed as one of the directions in the study of immune checkpoints. We believe that the effect of CRC immunotherapy can be achieved by increasing the expression of NKG2D on immune cells and inducing the expression of NKG2DL in tumor cells, which is the basis of the con-cept of this line of research.

Primary Solid and Cystic Tumours of the Exocrine Pancreas in Cats

Tumours of the exocrine pancreas are rare in cats and few cases are described in the literature. Cystic tumours of the pancreas are not included in the World Health Organization (WHO) international histological classification of tumours of domestic animals. The aim of this study was to characterize the pathology of primary epithelial tumours of the feline exocrine pancreas, with emphasis on cystic tumours. We reviewed tumours of the exocrine pancreas in 70 cats, including complete tumours or the entire pancreas (n=18) and excisional biopsy samples of pancreatic tumours (n=52). Macroscopically, the tumours were grouped as solid (n=45) or cystic (n=25). Solid tumours were subdivided into adenomas (n=5) and carcinomas (n=40) and cystic neoplasms into adenomas (n=15), carcinomas (n=7) and cases with diverse growth patterns (n=3). All five grossly solid adenomas had acinar morphology, while the macroscopically solid carcinomas showed acinar (n=17), tubular (n=14) or mixed (n=9) growth microscopically. Cystic adenomas had acinar (n=2), tubular (n=12) or mixed (n=1) growth, while cystic carcinomas had exclusively tubular growth (n=7). Three cases with cystic lesions showed diverse histopathological growth patterns. The clinical outcome was available in 57 cases. The majority of cats with carcinomas died or were humanely destroyed during or shortly after surgery (n=32). However, 2/7 animals with cystic carcinomas showed longer survival times. Cats with cystic adenomas had survival times of up to 5 years. The results of this study show that cystic pancreatic tumours should be considered a differential diagnosis in cats with cystic intra-abdominal masses, even though these are not yet described in the WHO classification. Based on the relatively long survival times of cats with cystic adenomas, complete resection with subsequent histopathological examination is recommended.

Efficacy of quercetin against chemically induced murine oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is the most common form of head and neck cancer, and oxidative damage is associated with the development of OSCCs. Antioxidants have therefore been proposed for use as chemoprotective agents against different types of cancer. In the present study, the effect of the antioxidant quercetin, administered at doses of 10 and 100 mg/kg/day, was investigated in an experimental murine model of 4-nitroquinoline 1-oxide (4-NQO)-induced carcinogenesis. The survival of the treated animals, the plasmatic levels of reduced glutathione and the type and severity of lesions (according the International Histological Classification of Tumors and Bryne's Multifactorial Grading System for the Invasive Tumor Front) were assessed. Additionally, the organization of the extracellular matrix was analyzed by carbohydrate and collagen histochemistry, and immunohistochemistry was used to assess the expression of the tumor markers proliferating cell nuclear antigen and mutated p53. The results indicate that, despite the promising effect of quercetin in other studies, this drug is ineffective as a chemoprotective agent against 4-NQO-induced OSCC in mice at the assayed doses.

Combinations of Urinary Biomarkers for Surveillance of Patients with Incident Nonmuscle Invasive Bladder Cancer: The European FP7 UROMOL Project

We determined a combination of markers with optimal sensitivity to detect recurrence in voided urine after resection of an incident low grade, nonmuscle invasive bladder tumor. A total of 136 patients with G1/G2 nonmuscle invasive bladder tumor were included in the study at transurethral resection of the incident tumor. At least 3 followup urine samples were required for patient selection. DNA was extracted from the incident tumor and cell pellets of subsequently collected urine samples. We performed FGFR3, PIK3CA and RAS mutation analysis, and microsatellite and methylation analysis on tissue and urine DNA samples. We obtained 716 urine samples. The 136 patients experienced a total of 552 recurrences during a median 3-year followup. Sensitivity for detecting a recurrent tumor varied between 66% and 68% for the molecular tests after patient stratification based on tumor DNA analysis. A combination of markers increased sensitivity but decreased the number of patients eligible for a certain test combination. Combining urine cytology with FGFR3 analysis without stratifying for FGFR3 status of the incident tumor increased sensitivity from 56% to 76%. A combination of markers increased the percentage of patients eligible for urine based followup and the sensitivity of recurrence detection. Adding FGFR3 analysis to urine cytology could be valuable for noninvasive followup of patients with nonmuscle invasive bladder cancer.

Progressive Extracellular Matrix Disorganization in Chemically Induced Murine Oral Squamous Cell Carcinoma

Introduction. Oral squamous cell carcinoma (OSCC) is one of the ten most common cancers affecting the human population. Tumor pathogenesis implies a multistep process in which cells acquire features that enable them to become tumorigenic and ultimately malignant. The process of OSCC carcinogenesis can be reproduced in animal models, the OSCC induction with 4-nitroquinoline-1-oxide (4NQO) in mice is a widely used tool for studying tumor pathogenesis. Objective. The aim of the present study was to determine the progressive changes in basal lamina and connective tissue remodeling during 4NQO-induced OSCC carcinogenesis. Material and Methods. Samples were classified according to “International Histological Classification of tumors” in mild, moderate, and severe dysplasia and invasive carcinoma. Five samples of each pathologic entity and control healthy tongues were used. Immunohistochemical analysis of collagen IV as well as histochemical analysis of glycosylated molecules (PAS) and collagen I (Picro Sirius red) were performed. Results. During experimental-induced carcinogenesis by 4NQO a progressive basal lamina destruction and collagen I disorganization in adjacent connective tissue can be observed. Conclusion. Our results confirm previous studies that show alterations in extracellular matrix (ECM) in malignant lesions, validating the experimental carcinogenesis induced by 4NQO.

Modern histological and clinical classifications of tumours and tumour-like lesions of bones, peculiarities of their use and some aspects of orthopaedic oncomorphology

The article deals with examination of the WHO International Histological Classification of Tumours (2002) and some clinical classifications (TNM, ІCD-O, Ennekіng). From these positions and also on the basis of a great number of his own bioptic-histologic studies and many years of experience the author elucidated some aspects of clinical-morphological diagnosis, which are of great importance for orthopedic oncopathology practice. The history of creation of the WHO International Histological Classification of Tumours, the structure of its last 3rd edition (2002) and differences from the previous edition are briefly described. Peculiarities in the application of the above classifications of bone tumors are noted. Methods for revealing degrees of tumour malignancy and chemotherapeutic pathomorphosis of malignant bone tumours, detected with pathohistological examination, are assessed. The necessity of a close cooperation of doctors of different specialities (orthopaedists-oncologists, specialists in visualizing methods of examination and pathomorphologists) in the process of diagnosing and treating tumours and tumour-like lesions of bones is emphasized.

Chronic Restraint Stress in Oral Squamous Cell Carcinoma

Pathogenic processes have been identified that could associate chronic stress and cancer, but these findings have not been observed in oral cancer. This study examined the role of chronic restraint stress on the incidence and severity of OSCC induced with 4-nitroquinoline-1-oxide (4-NQO) in the tongues of CF-1 mice. One hundred twenty CF-1 male mice were divided into 4 groups: (A) received two treatments — restraint stress and induction of chemical carcinogenesis (n = 50); (B) induction of chemical carcinogenesis, without restraint stress (n = 50); (C) restraint stress (n = 10); and (D) control (n = 10). After 30 weeks, tongues were dissected and analyzed by conventional histopathology. The severity of OSSC was analyzed according to the International Histological Classification of Tumors and Bryne’s Multifactorial Grading System for the Invasive Tumor Front (ITF). Chronic stress induction was confirmed by plasma corticosterone levels. Results showed that chronic stress was induced with movement restriction (p ≤ 0.05, Mann-Whitney U-test). However, chronic stress did not increase the incidence (p > 0.05, Chi-square) or severity (p > 0.05, Mann-Whitney U-test) of the 4-NQO-induced OSSC in the tongues of CF-1 mice. These results suggest that there is no relationship between chronic stress (induced in mice by restraint) and the incidence and severity of OSSC.

Uterus tumours: an overview

Note Anatomically, uterine neoplasms may be localized at the corpus, isthmus (the transition between the endocervix and uterine corpus) and cervix. The fallopian tubes and uterine ligaments may also undergo tumour tranformation. This overview will focus on uterine cervix and corpus tumours, including benign, pre-malignant and malignant lesions. They may affect the endometrium, muscles or other supporting tissue. Uterine tumours may be histologically typed according to several classification systems. Those used most frequently are based on the WHO (World Health Organization) International Histological Classification of Tumours and on the ISGYP (International Society of Gynecological Pathologists). The most widely-accepted staging system is the FIGO (International Federation of Gynecology and Obstetrics) one.

Oral premalignant lesions: from the pathological viewpoint

Under the widely used World Health Organization (WHO) classification for the pathological diagnosis of oral premalignant lesions, dysplasia, which is graded as mild, moderate or severe, and carcinoma in situ (CIS), which is a non-invasive carcinoma, are classified as precursor lesions of oral squamous cell carcinoma. Since the first edition (Wahi et al. International histological classification of tumours no. 4, WHO, Geneva, 1971), the criterion for CIS--that all epithelial layers are replaced by atypical cells--has remained unchanged. However, this dysplasia-carcinoma sequence theory was introduced from the viewpoint of pathological changes in the uterine cervix: in contrast, almost all premalignant lesions and CIS of the oral mucosa show superficial maturation and differentiation. Based on this recognition, the squamous intraepithelial neoplasia (SIN) classification and Ljubljana classification were included in WHO's latest edition published in 2005. Although the WHO classification is commonly used in Japan, recent developments in oral oncology have promoted modifications of the classification used in this country. In 2005, the Working Group of the Japan Society for Oral Tumours advocated iodine staining and proposed a modified SIN system, and in 2007, the Working Committee of the Japanese Society for Oral Pathology (JSOP) reported a new CIS (JSOP) definition that included differentiated-type CIS. In 2010, based on these studies, a new entity--oral intraepithelial neoplasia (OIN)--was included in the first edition of General Rules for Clinical and Pathological Studies on Oral Cancer. In this review, we focus on the OIN/CIS (JSOP) new classification of premalignant lesions in oral mucosa, which further advances the concept of SIN.

Hysteroscopic Diagnosis of Stromomyoma

Stromomyomas are relatively rare uterine tumors that exhibit ultrastructural characteristics of both endometrial stromal and smooth muscle cells [ 1 Tang C.-K. Toker C. Ances I.G. Stromomyoma of the uterus. Cancer. 1979; 43: 308-316 Crossref PubMed Scopus (51) Google Scholar , 2 Oliva E. Clement P.B. Young R.H. Scully R.E. Mixed endometrial stromal and smooth muscle tumors of the uterus: a clinicopathologic study of 15 cases. Am J Surg Pathol. 1998; 22: 997-1005 Crossref PubMed Scopus (136) Google Scholar , 3 Geetha V. Rupashree S. Bhat S.S. Endometrial stromal nodule with smooth muscle differentiation. Ind J Pathol Microbiol. 2008; 51: 76-77 Crossref PubMed Scopus (6) Google Scholar ]. In most cases, differentiation of endometrial stromal and smooth muscle tumors can be made solely by routine light microscopic examination. The World Health Organization currently recognizes the existence of such a hybrid neoplasm in its classification of uterine tumors [ 4 Scully R.E. Bonfiglio T.A. Kurman R.J. Silverberg S.G. Wilkinson E.J. Histological typing of female genital tract tumors. in: World Health Organization International Histological Classification of Tumors. 2nd ed. Springer-Verlag, Berlin1994: 22 Google Scholar ]. Imaging examinations often lead to the misdiagnosis of stromomyomas as either leiomyosarcomas or leiomyoma cystic degeneration, whereas reliance on histologic examinations often results in stromomyomas being misdiagnosed as cellular leiomyomas [ 5 Oliva E. Clement P.B. Young R.H. Mesenchymal tumors of the uterus: selected topics emphasizing diagnostic pitfalls. Curr Diagn Pathol. 2002; 8: 268-282 Abstract Full Text PDF Scopus (17) Google Scholar ].

A classification of bone tumors

The main international classifications of tumours in the locomotor system were analysed. It was found out that the prognosis and course of tumours were most accurately and completely described by the WHO International Histological Classification of Tumours (2002), the TNM classification system (2002, 6th edition), the Enneking surgical staging system, the clinical-statistical classification, ICD-0 (1990, 2nd edition). The classifications play a key part in making diagnoses, helping oncologists to work following the same rules, improve old and introduce new methods of treatment.

MTP22-01: Neuroendocrine tumors

MTP22-01: Neuroendocrine tumors

Y1-01: Toward A New Histological Classification Of Lung Tumors

Y1-01: Toward A New Histological Classification Of Lung Tumors

A Comparison of Hexaminolevulinate Fluorescence Cystoscopy and White Light Cystoscopy for the Detection of Carcinoma In Situ in Patients With Bladder Cancer: A Phase III, Multicenter Study

We compared hexaminolevulinate (Hexvix) fluorescence cystoscopy with white light cystoscopy for detecting carcinoma in situ. In this multicenter study 298 patients with known or suspected bladder cancer underwent bladder instillation with 50 ml 8 mM hexaminolevulinate for 1 hour. Cystoscopy was then performed, first using standard white light and then hexaminolevulinate fluorescence cystoscopy. Lesions or suspicious areas identified under the 2 illumination conditions were mapped and biopsied for histological examination. In addition, 1 directed biopsy was obtained from an area appearing to be normal. Of 196 evaluable patients 29.6% (58 of 196) had carcinoma in situ, including 18 with carcinoma in situ alone, and 35 with carcinoma in situ and concomitant papillary disease, which was only detected on random biopsy in 5. Of the 18 patients with no concomitant papillary disease carcinoma in situ was detected only by hexaminolevulinate fluorescence in 4 and only by white light in 4. In the group with concomitant papillary disease carcinoma in situ was found only by hexaminolevulinate fluorescence in 5 patients and only by white light in 3. The proportion of patients in whom 1 or more carcinoma in situ lesions were found only by hexaminolevulinate cystoscopy was greater than the hypothesized 5% (p=0.0022). Overall more carcinoma in situ lesions were found by hexaminolevulinate than by white light cystoscopy in 22 of 58 patients (41.5%), while the converse occurred in 8 of 58 (15.1%). Biopsy results confirmed cystoscopy findings. Of a total of 113 carcinoma in situ lesions in 58 patients 104 (92%) were detected by hexaminolevulinate cystoscopy and 77 (68%) were detected by white light cystoscopy, while 5 were detected only on directed visually normal mucosal biopsy. Hexaminolevulinate instillation was well tolerated with no local or systemic side effects. In patients with bladder cancer hexaminolevulinate fluorescence cystoscopy with blue light can diagnose carcinoma in situ that may be missed with white light cystoscopy. Hexaminolevulinate fluorescence cystoscopy can be used in conjunction with white light cystoscopy to aid in the diagnosis of this form of bladder cancer.

Squamous cell lung carcinoma with surrounding pure nonmucinous bronchioloalveolar carcinoma (BAC)

Summary Bronchioloaveolar cell carcinoma (BAC) was defined by the WHO in 1999 to be a subtype of adenocarcinoma with a pure bronchioloalveolar growth pattern showing no evidence of stromal, vascular, or pleural invasion [Travis WD, Colby TV, Conin B, et al. Bronchioloalveolar carcinoma. In: Sobin LH, editor. WHO international histological classification of tumors, 3rd ed. Copenhagen, Denmark: Springer; 1999. p. 34–8]. Although there were some reports that BAC was presented together with squamous cell carcinoma, this is the first report that it might be transformed from surrounding pure nonmucinous BAC. Physicians should be aware that pure BAC could transform to squamous cell carcinoma, and that such cases might not respond to gefitinib.

Micropapillary Carcinoma of the Renal Pelvis and Ureter

MPC located in the upper urinary tract is rare with only 2 cases reported to date. We report clinical and histopathological data on 26 patients to increase the knowledge of this rare entity. A clinical and histopathological review was performed in 943 patients with a neoplasm in the renal pelvis or ureter, diagnosed between 1971 and 1998. We identified 26 patients with MPC. No patients were alive at the end of the study. Of the patients 11 had greater than 50% MPC and 15 had focal MPC (at least 10%). The incidence was 2.8%. Median patient age at diagnosis was 69 years (range 54 to 88) and the male-to-female ratio was 17:9. All except 4 patients had stage T3 disease or higher. Carcinoma in situ was identified in 64% of cases and vascular invasion was present in 81%. A total of 20 patients (77%) died of disease and only 7 survived longer than 5 years. The prognosis is poor since most patients with MPC of the renal pelvis and ureter initially present with advanced disease. Stage for stage the prognosis is not different from that in nonMPC urothelial cell carcinoma. Surgery is curative in less advanced cases. However, radiotherapy and systemic chemotherapy appear to be ineffective.

Bilateral Metachronous Ureteral and Renal Pelvic Carcinomas: Incidence, Clinical Presentation, Histopathology, Treatment and Outcome

Metachronous bilateral UUTTs are rare. The authors reported baseline and long-term followup data for all patients diagnosed in Western Sweden during a 28-year period. We performed a clinical and histopathological analysis of all patients in Western Sweden surgically treated for ureteral and renal pelvic tumors from 1971 to 1998. Of 768 patients a contralateral UUTT developed in 24 (3.1%) after a median of 46 months (range 2 to 232). The projected incidence after initial UUTT diagnosis was 2.7%, 5.8% and 6.5% at 5, 10 and 15 years, respectively. Median age of the 24 patients at initial UUTT diagnosis was 67 years and the median age at death was 77 years. Bladder cancer was significantly more common among patients with bilateral UUTT compared to those with unilateral UUTT (83% vs 31%, p <0.0001). Routine followup urography was normal in 9 patients 2 to 11 months before the diagnosis of the contralateral UUTT. Nine patients died of UUTT and 5 patients died of bladder cancer. Bilateral subsequent upper tract tumors are rare, in general diagnosed at an older age and associated with short survival. Many patients die of bladder cancer and it may be possible to improve survival if the bladder cancer is treated early and aggressively. Routine followup urography is not indicated among patients with a tumor-free bladder and a history of UUTT.

Gallbladder carcinoma: the role of p53 protein overexpression and Ki‐67 antigen expression as prognostic markers

The overexpression of p53 protein and the expression of Ki-67 antigen may affect the survival of patients with gallbladder carcinoma. This association has been tested in a series of 41 patients with relatively early carcinoma of the gallbladder. Forty-one surgical specimens from patients with a postoperative histological diagnosis of gallbladder carcinoma were studied. All patients were operated by simple cholecystectomy only because the tumours were not advanced and/or their general condition was poor. Patients submitted to radical operations were excluded. p53 expression was calculated from nuclear staining according to the intensity and extent of positive cells, as graded on a scale from 1 to 3; a combined score of >3 was considered as overexpression. Ki-67 expression was calculated by the MIB-I index: the percentage of positively stained tumour cell nuclei out of the total tumour cells counted (n = 1000); >20% of stained cells was considered positive. Twenty-nine gallbladder carcinomas (71%) overexpressed p53 protein in the cell nuclei. No significant differences were found in relation to cell differentiation on the level of tumour infiltration through the gallbladder wall. Five-year survival of patients with gallbladder carcinoma overexpressing p53 was 17.2%, while survival of patients without p53 overexpression was 30% (not significant). Twenty-four cases (58.5%) were considered positive for the MIB-I index. There were no differences between the grade of cell differentiation and wall infiltration. Five-year survival of the patients with a MIB-I positive index was 9.2% as opposed to 27.7% for those with a negative index (not significant). p53 protein nuclear overexpression and Ki-67 protein expression in gallbladder carcinoma were not related to histological differentiation, level of gallbladder wall invasion or patient survival.

Histological typing of prostate tumours (World Health Organisation, international histological classification of tumours, 2nd edn). FK Mostofi, IA Sesterhenn and CJ Davis, in collaboration with LH Sobin and pathologists from ten countries. Springer‐Verlag, Berlin, 2002. No of pages: 115 (with colour illustrations). £49.00. ISBN: 3 540 42256 0

Histological typing of prostate tumours (World Health Organisation, international histological classification of tumours, 2nd edn). FK Mostofi, IA Sesterhenn and CJ Davis, in collaboration with LH Sobin and pathologists from ten countries. Springer‐Verlag, Berlin, 2002. No of pages: 115 (with colour illustrations). £49.00. ISBN: 3 540 42256 0

Central odontogenic fibroma granular cell variant: A case report and review of the literature

In 1992 the World Health Organization (WHO), in its revised classification of odontogenic tumors, 1 Kramer IRH Pindborg JJ Shear M Histological typing of odontogenic tumors. in: World Health Organization International Histological Classification of Tumours (ed 2). Springer-Verlag, Berlin, Germany1992: 22 Google Scholar defined the odontogenic fibroma (OF) as a benign ectomesenchymal proliferation characterized by fibroblastic tissue containing varying amounts of apparently inactive odontogenic epithelium. The WHO distinguishes between a central (intraosseous) and peripheral forms but does not subdivide the central form of OF. Other authors 2 Gardner DG The central odontogenic fibroma: An attempt at clarification. Oral Surg Oral Med Oral Pathol. 1980; 50: 425 Abstract Full Text PDF PubMed Scopus (89) Google Scholar , 3 Gardner DG Central odontogenic fibroma current concepts. J Oral Pathol Med. 1996; 25: 556 Crossref PubMed Scopus (64) Google Scholar have distinguished between a so-called simple type and a complex type commonly referred to as the WHO type. The WHO type is more cellular than the simple type, with odontogenic epithelial cells forming a substantial part. Calcifications and abundant collagen fibers are often exhibited. 2 Gardner DG The central odontogenic fibroma: An attempt at clarification. Oral Surg Oral Med Oral Pathol. 1980; 50: 425 Abstract Full Text PDF PubMed Scopus (89) Google Scholar , 3 Gardner DG Central odontogenic fibroma current concepts. J Oral Pathol Med. 1996; 25: 556 Crossref PubMed Scopus (64) Google Scholar