Necrotizing sialometaplasia of the lip simulating squamous cell carcinoma

A case of necrotizing sialometaplasia of the lip in an 68-year-old pipe smoker is described. Necrotizing sialometaplasia is a self-healing non-neoplastic disease probably of ischaemic nature. Thirty-nine cases of sialometaplasia are described in the literature up to early 1979. These cases appeared in the palate, nasal cavity, gingiva, lip, hypopharynx and maxillary sinus. Six cases have also been reported from major salivary glands. Histologically there is necrosis of mucous cells with partial replacement by squamous epithelium. This entity has often been mistaken for squamous or mucoepidermoid carcinoma. One has to be familiar with the existence of necrotizing sialometaplasia in order to avoid subjecting the patient unnecessary and potentially mutilating surgery.     

Necrotizing sialometaplasia of the parotid gland associated with angiocentric T‐cell lymphoma: A case report and review of the Literature

A very rare case of necrotizing sialometaplasia of the parotid gland associated with angiocentric T‐cell lymphoma was described. A 66‐year‐old male had left neck and pharyngeal masses and biopsy specimen showed a monotonous proliferation of atypical lymphoid cells with massive necrosis in the parotid gland. Angiocentric pattern or vascular invasion by the lymphoid cells was observed and the involved parotid gland exhibited squamous metaplasia of the ducts and acini; necrotizing sialometaplasia. Immunohistochemical analysis revealed a cytotoxic T‐cell phenotype of the lymphoid cells (CD3+, CD4‐, CD5+, CD8+, CD56‐, Granzyme B+, TIA‐1+, Perforin‐) but in situ hybridization showed no relation to Epstein‐Barr virus. Although necrotizing sialometaplasia is relatively rare in the parotid gland, angiocentric T‐cell lymphoma should be considered for a causative condition of necrotizing sialometaplasia.     

Primary myoepithelial carcinoma of the lung: a case report and review of literature

Primary myoepithelial carcinoma of the lung is a very rare tumor arising from the salivary glands of the respiratory epithelium. Since it was first described by Higashiyama et al. in 1998, to the best of our knowledge, only eight actual cases reported in the English-language literature so far. The diagnosis is based entirely on histological and immunohistochemical evaluations. We report a primary myoepithelial carcinoma in a smoker 47-year-old Chinese man, who was referred to our institution for hemoptysis. Computed tomography revealed a 65 mm×78 mm solid mass in the left lower lobe of lung. The patient underwent the left lower lobe resection. The final histopathological diagnosis was primary myoepithelial carcinoma of the lung. Given the rare occurrences of this tumor, appropriate recommendations for treatment are difficult to formulate. Although classified as low-grade tumor, it has a significant rate of distant metastasis. Herein we report a case of a primary myoepithelial carcinoma of the lung and present a brief review of the literature.     

Cytokeratin 7: a useful adjunct in the diagnosis of chromophobe renal cell carcinoma

AIMS: The histopathological diagnosis of chromophobe renal cell carcinoma can present a diagnostic challenge, as these tumours can resemble either conventional renal cell carcinoma or oncocytoma. The aim of this study was to determine whether cytokeratin 7 expression is of practical use in the distinction of these three entities. METHODS AND RESULTS: A total of 40 cases previously diagnosed as either chromophobe renal cell carcinoma, conventional renal cell carcinoma or oncocytoma were identified. A representative section of each was stained with H&E and cytokeratin 7. Following independent review of the cases by three pathologists, a consensus diagnosis for each case was reached and the pattern of cytokeratin 7 staining was assessed. There were 12 cases of chromophobe renal cell carcinoma in the study, all of which showed a characteristic peripheral membrane pattern of staining for cytokeratin 7. Seventeen of the 18 cases of conventional renal cell carcinoma studied were negative for cytokeratin 7, while one case showed weak focal staining of <5% of the cells. The 10 cases of oncocytoma showed patchy weak to moderate cytoplasmic expression of cytokeratin 7, without the characteristic peripheral membrane accentuation seen in the chromophobe carcinomas. CONCLUSIONS: Immunohistochemical staining for cytokeratin 7 appears to be a useful adjunct in the diagnosis of chromophobe renal cell carcinoma, and in distinguishing this tumour from both oncocytoma and conventional renal cell carcinoma.     

Adenosquamous carcinoma of the head and neck: criteria for diagnosis in a study of 12 cases

AIMS: Adenosquamous carcinoma (ASC) of the head and neck is an unusual neoplasm in which a general consensus with regard to diagnostic criteria has not yet been reached. In this study we report the clinicopathological results of 12 ASCs, with special attention to their histological and immunohistochemical characteristics in order to define this neoplasm more precisely. METHODS AND RESULTS: All the patients were male with a peak incidence in the sixth decade of life. The tumours were located most frequently in the larynx and oral cavity, followed by the nasal cavity and pharynx. ASCs had two distinct histological components. The most extensive one was an usual keratinizing squamous cell carcinoma, arising from the surface epithelium, where characteristically severe dysplasia or carcinoma in situ was found in all cases. The second component was an adenocarcinoma, usually displayed in the deepest areas of the tumour. Evidence of origin from salivary or seromucinous glands was not found. Immunohistochemical studies demonstrated in most cases positivity of glandular differentiated areas for carcinoembryonic antigen (CEA) (11/12), CK7 (9/12) and CAM5.2 (7/12), whereas the squamous cell component was unreactive or reacted only focally for these markers. High-molecular-weight cytokeratin 34BE12 was positive in both components and CK20 was always negative. All cases showed high expression of Ki67 antigen. Most of them had overexpression of p53 (8/12) and DNA aneuploidy (10/12). Fifty percent of patients with ASC died of disease after a mean period of 23 months (range 12-35 months). CONCLUSIONS: ASC of the head and neck is an aggressive neoplasm that originates in the surface epithelium of the upper respiratory tract. Severe dysplasia or carcinoma in situ is usually found and its recognition helps to make the diagnosis. In addition to mucin stains, positive immunoreactivity for CEA, CK7 and CAM5.2 helps to identify the glandular component.     

Primary cutaneous myoepithelial carcinoma: a case report and review of the literature

This study describes a case of primary myoepithelial carcinoma of the skin and reviews the available literature on this topic. Myoepitheliomas and carcinomas arise most frequently from myoepithelial cells within the salivary glands but are found in many anatomical locations. We documented a case of an 80‐year‐old man with a 2 × 2 × 1 cm tumour located on the scalp. This tumour emerged over a period of 2 months. The tumour was radically excised, and histological examination revealed a cutaneous myoepithelial carcinoma. At an 18‐month follow‐up, no recurrence of the tumour was found. A systematic literature search identified 23 papers that reported 58 cases of cutaneous myoepitheliomas and myoepithelial carcinomas. All cases are reviewed in the presented paper. This case report and literature review serves to increase awareness regarding myoepithelial carcinomas. These tumours exhibit high metastatic potential, and it is thus very important to perform radical surgery.     

Pulmonary myoepithelial carcinoma resembling matrix‐producing carcinoma of the breast: case report and review of the literature

Tanahashi J, Kashima K, Daa T, Yada N, Tanaka K‐I, Kawano Y, Yokoyama S. Pulmonary myoepithelial carcinoma resembling matrix‐producing carcinoma of the breast: case report and review of the literature. APMIS 2010; 118: 401–6. We report a case of pulmonary myoepithelial carcinoma with extensive myxohyaline stroma, resembling matrix‐producing carcinoma of the breast. A 76‐year‐old Japanese man presented with a nodular lesion in the left lung (S8), and underwent partial resection of the left lower lobe. Microscopically, the resected tumor was relatively well circumscribed with central hypocellular myxohyaline and peripheral hypercellular area. In the central area, eosinophilic and clear polygonal cells proliferated in a cord‐like or reticulated pattern with extensive myxohyaline stroma, while the peripheral area was composed of solid lobules of different shapes and sizes with occasional comedonecrosis. The tumor cells were markedly atypical with frequent mitotic figures. Vascular and lymphatic invasion was evident with regional lymph node metastasis. No squamous or glandular differentiation was evident in the tumor. Immunohistochemical staining implied myoepithelial differentiation. The patient developed multiple brain metastases, and died of the disease 11 months after the surgery. In this report, we discuss the histopathologic uniqueness of the present case together with a review of the literature.     

Immunocytochemical studies of epithelial markers in pleural and peritoneal effusions as an adjunct to cytologic diagnosis

Monoclonal antibodies were used in an indirect immunoperoxidase assay to investigate 83 smears of pleural or peritoneal effusions for expression of the epithelial markers MAM-6, MAM-3, and carcinoembryonic antigen (CEA). All but one smears containing tumor cells according to the evaluation of H&E preparations were positive for one, two or all three markers, the exception being a malignant melanoma. Three of 5 cases, suspicious by routine cytology, exhibited marker expression in a different number of cells and thus confirmed the cytological diagnosis. Five of 63 cytologically negative smears exhibited single cells or small cell clusters positive for up to three markers. Four of these patients were found to suffer from metastatic cancer, as established by clinical follow-up and subsequent biopsy or autopsy, respectively. Felty's syndrome and concomitant serositis were diagnosed and confirmed by autopsy in one of the MAM-6 positive cases with negative cytology. The comparatively strong MAM-6 expression in some mesothelial cells of this patient might have been induced by abnormal stimulation due to the rheumatic disease. The results of this study encourage wider use of immunocytochemistry as an adjunct to cytological diagnosis in effusions.     

Small cell undifferentiated carcinoma of the submandibular gland: immunohistochemical evidence of myoepithelial, basal and luminal cell features

A primary small cell undifferentiated carcinoma of the submandibular gland is reported. Histological studies revealed that the major part of this tumor was composed of cells slightly larger (10-14 microm) than lymphocytes. These tumor cells showed myoepithelial-cell differentiation, which was confirmed by the immunohistochemical and ultrastructural findings. Furthermore, some of them showed luminal-cell and basal-cell differentiation immunohistochemically. However, there was no evidence of neuroendocrine differentiation. These findings demonstrated that the tumor had the features of all the salivary ductal components (myoepithelial, basal, and luminal cells) and supported that the tumor might arise from the salivary duct. Furthermore, it supports the hypothesis of multipotential stem cells as the origin for small cell undifferentiated carcinomas in salivary glands.     

The cell with a thousand faces: detection of myoepithelial cells and their contributions in the cytological diagnosis of salivary gland tumors

Myoepithelial cells are an important component of salivary gland tumors and are partly responsible from the diverse histology of them. In this study, we focus on the myoepithelial cell differentiation by using cytological morphology in a various types of salivary gland tumors especially with regard to their contribution to the diagnosis. The relation of myoepithelial cells with stromal matrix and the associated epithelial cells were evaluated. Cytologic slides of one hundred and forty one benign and twenty malignant salivary gland tumors were examined for identification of morphologically different myoepithelial cells such as; spindle-stellate, polygonal-epitheloid, plasmacytoid, basal and clear types. The best examples of myoepithelial cells were detected in pleomorphic adenomas, in some monomorphic adenomas and in the adenoid cystic carcinoma cases. Most of the pleomorphic adenomas were composed more than one type of myoepithelial cells and epitheloid-spindle cell combination was frequent. Basal and clear cell types of myoepithelial cells closely resembled the epithelial cells and their identification was relatively difficult. Identification of myoepithelial cell types was easier when they were associated with stromal matrix material and stood as a secondary layer around tubule-forming epithelial cells. Myoepithelial cell components of various salivary gland tumors may be quite different and identification of myoepithelial cell types may pose difficulties. A confident cytologic identification of myoepithelial cells may be critical part of diagnosing salivary gland tumors.     

S100 protein in human mammary tissue--immunoreactivity in breast carcinoma, including Paget's disease of the nipple, and value as a marker of myoepithelial cells

The expression of S100 protein, as assessed by immunohistochemistry, has been evaluated in 101 mammary carcinomas of various histological types, including Paget's disease of the nipple. S100 immunoreactivity was seen in 44 of 101 primary carcinomas, including in situ lesions. It was present in all histological types, with the exception of mucoid carcinoma. In the 33 cases with associated Paget's disease of the nipple, S100 expression was seen in the Paget's cells in six cases. S100 immunoreactivity has been suggested as a marker of myoepithelial cells, but in our hands staining of these cells is less consistent using the S100 antibody than with antibodies to actin. Furthermore, S100 protein is also expressed by some luminal epithelial cells. Therefore, in contrast to actin immunoreactivity, S100 immunoreactivity is not a reliable means of differentiating between luminal epithelial and myoepithelial cells. The possibility that staining with antibody to S100 protein may be affected by methods of fixation and immunohistochemical technique is discussed.     

Latex particle agglutination test as an adjunct to the diagnosis of bacterial meningitis

The present study aimed to review the results of microscopic examination, routine culture and antigen detection by latex particle agglutination test (LPAT), in order to evaluate the diagnostic value of the LPAT in establishing the aetiological diagnosis of bacterial meningitis. LPAT was done in 65 clinically suspected meningitis cases ranging from 5 days to 60 years of age and was compared with culture and Gram stain. Using LPAT, an aetiological diagnosis could be done in 10 out of 65 (15.4%) cases of bacterial meningitis. In contrast, Gram stain and culture showed 16.9 and 23.1% positivity, respectively. LPAT correlated well with Gram stain and culture and can be recommended as an adjunct laboratory test for rapid aetiological diagnosis of bacterial meningitis for prompt institution of proper antibiotics.     

Spindle cell carcinoma of head and neck: an immunohistochemical and molecular approach to its pathogenesis

BACKGROUND: Spindle cell carcinoma (SpCC) is a rare microscopic type of cancer of the mouth and oropharynx. Although SpCC is thought to arise from squamous cell carcinoma (SCC), it carries a worse prognosis. AIM: To find out the difference in immunohistochemical expression of cytokeratin, vimentin and smooth-muscle actin, and mutational alterations in the K-ras oncogene between the two tumours, in an attempt to characterise SpCC. METHODS: Immunohistochemical analysis was performed by standard avidin-biotin complex method in 35 cases each of SpCCs and SCCs. DNA extracted from paraffin wax-embedded tumours was used for PCR followed by single-strand conformation polymorphism for mutational analysis of K-ras exon 1 and exon 2. RESULTS: In the SpCC group, cytokeratin positivity was significantly higher in epithelial areas (52.2%) than in spindle cell areas (16.1%), whereas vimentin was more positive in spindle cell areas (18.7%) than epithelial areas (2.7%). Cells intermediate between epithelial and spindle cell areas were consistently positive for both cytokeratin and vimentin. Cytokeratin was found to be significantly more positive in SCC (72.6%) than the squamous component and spindle cell component of SpCC. In this study, no mutation was detected in the K-ras gene of either the SpCC or SCC group. CONCLUSIONS: The spindle cell component of SpCC is intermixed with cells that are morphologically mesenchymal but express dual antigen-positivity characteristic of epithelial (cytokeratin) and mesenchymal (vimentin) cells. These, possibly, are cells in transition suggesting that SpCC may be a sarcomatous metaplasia of SCC.     

Rhabdomyoma of the head and neck: morphology and differential diagnosis

Rhabdomyomas of the head and neck are exceptionally rare benign mesenchymal tumors. Although histology is very characteristic, several differential diagnoses have to be considered. We investigated five patients with extracardiac rhabdomyoma of the head and neck (median age 65.9 years), four of them presenting with adult rhabdomyoma (AR) and one with fetal rhabdomyoma (FR). We analyzed the histological findings, with special regard to separation from hibernoma (two patients) and granular cell tumor (GCT; six patients, median age 31 years). Both FR and AR showed polygonal eosinophilic cells with peripherally or centrally localized nuclei and cross striations, while in hibernoma, multivacuolated cells with centrally localized nuclei were detected. In GCT, polygonal eosinophilic cells with granular periodic-acid-Schiff-positive cytoplasm were found; in one case, atypical GCT with increased pleomorphism and mitotic rate was observed. Pseudoepitheliomatous hyperplasia occurred both in FR and GCT. Immunohistochemically, rhabdomyomas were strongly positive for myogenic markers (desmin, actin, and myoglobin) but negative for S-100, while hibernoma and GCT strongly expressed S-100. Concerning the differential diagnosis of rhabdomyoma, GCT has to be especially considered since this tumor can undergo malignant transformation.     

Multifocal,nascent, and invasive myoepithelial carcinoma (malignant myoepithelioma) of the breast: an immunohistochemical and ultrastructural study

This report describes the light microscopic (LM), immunohistochemical (IHC), and electron microscopic (EM) features of a multifocal, nascent, and invasive myoepithelial carcinoma of the breast. By LM, the spindle cells disclosed fibrillar acidophilic cytoplasm, mild nuclear atypia, and a low mitotic index. Myoepithelial differentiation was established through IHC (single- and double-labeling techniques) and EM: periductal and infiltrating spindle cells coexpressed total muscle actin, alpha-smooth muscle actin, vimentin, cytokeratin 14, and pankeratin, and their EM features were characteristic of myoepithelial cells, i.e., perinuclear tonofilaments, subplasmalemmal bundles of microfilaments with dense bodies, intermediate junctions, poorly developed desmosomes, pinocytic vesicles, and fragmented external lamina. No invasive epithelial cells disclosed luminal differentiation (by LM, IHC, EM), identifying, thus, this neoplasm as a pure spindle cell myoepithelial carcinoma of the breast.     

Immunoreactivity for c-kit and p63 as an adjunct in the diagnosis of adenoid cystic carcinoma of the breast.

Adenoid cystic carcinoma of the breast represents a unique clinicopathologic entity with a variable histological appearance and a relatively indolent clinical course in most of the cases. Adenoid cystic carcinoma may be difficult to differentiate from infiltrating duct carcinomas, and in particular from tubular and cribriform carcinomas, especially in core or vacuum-assisted biopsies. We evaluated the prevalence of c-kit, p63, and e-cadherin immunoreactivity in a series of 20 adenoid cystic carcinomas, comparing the results with those obtained in a series of infiltrating tubular carcinomas and infiltrating cribriform carcinomas. The hormone receptor status, proliferation labeling index, and HER/2 immunoreactivity had been previously investigated in all the cases. Three (15%) adenoid cystic carcinomas and all infiltrating tubular and cribriform carcinomas showed estrogen receptor and/or progesterone receptor immunoreactivity (P < 0.00001 for estrogen and P = 0.00002 for progesterone receptors). Adenoid cystic carcinomas consistently lacked any immunoreactivity for HER/2, whereas three (15%) infiltrating and cribriform carcinomas showed weak and incomplete membrane staining (P = 0.23077). Membranous immunoreactivity for c-kit was found in all except one (predominantly basaloid) adenoid cystic carcinomas (95%), and in none of the infiltrating tubular and cribriform carcinomas (P < 0.00001). Nuclear immunoreactivity for p63 was found in all except three (predominantly basaloid) adenoid cystic carcinomas (85%) and in none of the infiltrating tubular and cribriform carcinomas (P < 0.00001). All infiltrating tubular and cribriform carcinomas and 18/20 (90%) adenoid cystic carcinomas showed immunoreactivity for e-cadherin (P = 0.48718). In summary, adenoid cystic carcinomas showed the following phenotype: estrogen receptor-/progesterone receptor-/c-kit+/p63+ (13 cases, 65%), estrogen receptor-/progesterone receptor/c-kit+/p63- (three cases, 15%), estrogen receptor-/progesterone receptor-/c-kit-/p63+ (one case, 5%), estrogen receptor+/progesterone receptor+/c-kit+/p63+ (two cases, 10%), and estrogen receptor+/progesterone receptor-/c-kit+/p63+ (one case). By contrast, all the infiltrating tubular and cribriform carcinomas showed the estrogen receptor+/progesterone receptor+/c-kit-/p63- phenotype. Our data provide evidence that immunoreactivity for c-kit and/or p63 may be useful in differentiating adenoid cystic carcinomas from other types of breast cancer.     

Expression of cancer/testis (CT) antigens in squamous cell carcinoma of the head and neck: Evaluation as markers of squamous dysplasia

Cancer/testis (CT) antigens, normally only expressed in germ cells of adult testis, can be activated in malignancy as tumor-specific antigens. The potential value of CT antigens as biomarkers in the evaluation of mucosal squamous precursor lesions of the head and neck has not been investigated. The expression of 8 CT antigens (MAGE-A, GAGE, NY-ESO-1, CT7, CT10, SAGE1, CT45 and NXF2) in 76 cases of invasive head and neck squamous cell carcinoma (SCC) was evaluated immunohistochemically. 65 mucosal biopsies of squamous dysplasia and 55 squamous papillomas with dysplasia were analyzed for 6 CT antigens, using an antibody cocktail. Of invasive SCC, 66% (50/76) expressed at least one CT antigen, most commonly MAGE-A (47%). Among the biopsies, only 1 of 55 squamous papillomas was CT-positive, whereas 8 of 65 (12%) squamous dysplasia lesions were CT-positive. These 8 CT-positive biopsies were from 6 patients, 3 of which had concurrent or subsequent SCC. CT antigens are frequently expressed in head and neck SCC; however, there was no difference in the clinicopathological characteristics or behavior of CT-positive tumors compared to CT-negative tumors. The usefulness of CT antigens as positive predictors for SCC in squamous dysplasia biopsies remains to be determined by long-term follow-up in larger cohorts.     

Utility of high molecular weight cytokeratins, but not p63, in the differential diagnosis of neuroendocrine and basaloid carcinomas of the head and neck

High-grade neuroendocrine carcinomas of the head and neck overlap significantly in morphology with both basaloid squamous and solid-type adenoid cystic carcinomas. High-grade neuroendocrine carcinomas have sheets of small cells with scant cytoplasm, granular chromatin, and inconspicuous nucleoli. Basaloid squamous and adenoid cystic carcinomas are aggressive variants of their respective tumor types which both have nests of basaloid tumor cells with round nuclei, little cytoplasm, and inconspicuous nucleoli. As the management and prognosis of these tumors are very different, it is important to differentiate them. We performed high molecular weight cytokeratin (CK) and p63 immunohistochemistry on 19 neuroendocrine carcinomas, 18 basaloid squamous carcinomas, and 11 solid-type adenoid cystic carcinomas. All tumors were immunostained for p63, CK 34betaE12, CK 5/6, synaptophysin, chromogranin-A, S-100, and smooth muscle actin. All basaloid squamous and adenoid cystic carcinomas were positive for CK 5/6 and 34betaE12. Only 4 and 5 of the 19 neuroendocrine carcinomas, respectively, were positive for these markers. Staining was focal in the neuroendocrine cases when positive, whereas almost all basaloid squamous and adenoid cystic carcinomas showed strong staining. Almost all tumors of each type were positive for p63, including neuroendocrine carcinomas, but with different staining patterns. Basaloid squamous carcinomas were diffusely positive, neuroendocrine carcinomas were diffusely positive, but with weak staining, and adenoid cystic carcinomas showed a distinct pattern with staining at the periphery of the cell nests only. We conclude that high molecular weight cytokeratin immunostaining is helpful in distinguishing high-grade neuroendocrine carcinomas from similar tumor types.     

p53 immunolocalization in cell block preparations of squamous lesions of the neck: an adjunct to fine-needle aspiration diagnosis of malignancy

OBJECTIVE: Mutations of the p53 tumor suppressor gene, with consequent nuclear p53 protein accumulation, are among the most common genetic abnormalities in human cancers. The purpose of this study was to determine the utility of p53 immunostaining as an adjunct to the diagnosis of malignancy in fine-needle aspirations of squamous lesions of the neck. MATERIALS AND METHODS: Using a monoclonal antibody to the p53 protein and a standard avidin-biotin complex technique, immunostaining was performed on paraffin-embedded cell blocks of 20 cases with the following cytologic diagnoses: (1) metastatic squamous cell carcinoma (SCC) (7 cases); (2) atypical squamous cells, SCC cannot be excluded (7 cases); and (3) cytologic findings consistent with branchial cleft cyst (6 cases). Tissue or clinical follow-up was available in all cases. RESULTS: Five (71%) of 7 cases with an unequivocal cytologic diagnosis of metastatic SCC were positive for p53 protein. Tissue follow-up confirmed metastatic SCC in all of these 7 cases. Of the 7 cases with cytologic diagnosis of atypical squamous cells, 2 were negative and 5 (71%) were positive for p53 protein. Subsequent excisional biopsies in these cases revealed metastatic SCC (6 cases) and branchial cleft cyst (1 case). The squamous cells in all 5 cases with cytologic findings consistent with branchial cleft cyst were negative for p53 protein; tissue follow-up confirmed the diagnoses of branchial cleft cyst in 4 cases. In the remaining 2 cases excision was not performed, as the cystic lesion was completely decompressed and, clinically, no recurrences were identified at 14 and 8 months of follow-up. CONCLUSIONS: Our findings suggest that p53 immunostaining is helpful in differentiating benign and malignant squamous lesions. While negative staining for p53 does not exclude malignancy, positive immunostaining may aid in accurate fine-needle aspiration diagnosis of malignancy in cytomorphologically equivocal squamous lesions of the neck.