Identification of Campylobacter pylori in gastric biopsy smears

The use of gastric biopsy imprint smears to diagnose Campylobacter pylori was compared with the use of tissue sections and cultures. Multiple gastric biopsies were taken from the mucosa of 42 patients during endoscopy. Imprint smears were prepared from the samples used to make tissue sections; other samples were used for microbiologic culture. There was a good concordance (93%) between the morphologic diagnosis of C pylori in the air-dried, Giemsa-stained smears and the tissue sections; the cytologic preparations were clearly positive in six cases (14%) whose sections contained low numbers of the organisms. There was a concordance of 83% between the combined morphologic techniques and the bacteriologic culture. Six positive cases were detected only by the morphologic techniques while one positive case was detected only by bacteriologic culture. C pylori was identified in one or more preparations of the antral biopsy specimens in 23 (55%) of the 42 cases, including 23 (74%) of the 31 cases with a final diagnosis of gastritis or ulcer. These results show the usefulness of the cytologic study of gastric biopsy smears in diagnosing C pylori infections.     

Semiquantitative assessment of c-erbB-2 (HER-2) status in cytology specimens and tissue sections from breast carcinoma

OBJECTIVE: To determine whether various methods of fixation of surgical pathology specimens from breast carcinomas would influence the outcome of evaluation of the expression levels of c-erbB-2 (HER-2). For this, comparisons were made between (1) alcohol-fixed (95%) and air-dried smears from fresh surgical pathology specimens of breast carcinomas, and (2) formalin-fixed, paraffin-embedded tissue sections of the same specimens. STUDY DESIGN: Alcohol-fixed and air-dried smears or touch preparations were made from 30 fresh mastectomy/lumpectomy surgical pathology specimens from breast carcinomas. Immunohistochemistry was performed using the c-erbB-2 primary antibody against the extracellular domain of the c-erbB-2 gene product. Staining was simultaneously performed on formalin-fixed, paraffin-embedded tissue sections of the same specimens. A semiquantitative approach was used for evaluation of immunostaining by three independent investigators, and a consensus was reached. RESULTS: A total of 30 cases were reviewed. Tissue positivity was determined for c-erbB-2 in: 73% of alcohol-fixed specimens (n = 13 [3+] and n = 9 [2+]), 67% of air-dried smears (n = 9 [+3] and n = 11 [+2]) and 47% (n = 8 [+3]) and n = 6 [+2]) of formalin-fixed, paraffin-embedded tissue specimens. All formalin-fixed tissue specimens that were determined to positively express c-erbB-2 were also found to be positive on the alcohol-fixed smears. CONCLUSION: The incidence of c-erbB-2 expression in fresh cytologic material is significantly higher (P < .05) than in formalin-fixed, paraffin-embedded tissue. Alcohol-fixed smears demonstrate a slightly higher percentage of cell staining and stronger intensity of c-erbB-2 expression than the matched, air-dried smears. This is a sensitive and simple processing method that can be routinely applied in surgical pathology or fine needle aspiration biopsy specimens for the detection of c-erbB-2 (HER-2), with clinical implications.     

Evaluation of abdominal fat pad aspiration cytology and grading for detection in systemic amyloidosis

OBJECTIVE: To evaluate the diagnostic efficacy of abdominal fat pad aspiration cytology as a screening procedure for systemic amyloidosis and to assess the clinical usefulness of semiquantitative grading criteria of fat pad amyloid deposits. STUDY DESIGN: Aspiration cytology samples from 297 cases of abdominal fat pad were retrospectively analyzed for amyloid deposits. The smears were graded semiquantitatively. The deposits in the smears were compared with histologic evidence of amyloidosis in deeper tissues in 44 cases. RESULTS: Retrospective analysis of 297 cases of aspiration cytology revealed amyloid in 90 cases. Follow-up biopsies from deeper tissues in 44 cases showed presence of systemic amyloidosis in 13 cases. The sensitivity and specificity of abdominal fat pad fine needle aspiration cytology was 78% and 93%, respectively. The positive predictive value was 84% and negative predictive value 90%. CONCLUSION: Fat pad aspiration cytology is a useful screening procedure for diagnosis of systemic amyloidosis. Patients with grade 1 deposits should not undergo a toxic therapeutic regimen on the basis of fat pad cytology alone; histologic confirmation of visceral amyloid deposition in deeper tissue is advised. Patients with grades 2 and 3 deposits may undergo suitable therapy for amyloidosis.     

Fine needle aspiration cytology of the testis as the first-line diagnostic modality in azoospermia: a comparative study of cytology and histology

Objectives:  Male factors are responsible for about half of all infertility cases. Until recently, testicular biopsy was the standard method to ascertain the aetiology of azoospermia. Fine needle aspiration cytology has gained increasing popularity as a simple and minimally invasive procedure that can help in assessing testicular function accurately. This study was aimed at addressing the question whether testicular fine needle aspiration (FNA) may be used as a first-line diagnostic modality in azoospermia and to assess its usefulness in the diagnostic protocol.
Methods:  The FNA was performed in 78 consecutive azoospermic patients. To obviate sampling errors both testes were aspirated, except when contraindicated. Routine haematoxylin and eosin as well as Romanowsky staining was performed on the smears.
Results:  The smears were categorized on cytological examination into normal spermatogenesis in 35 (50%) patients, Sertoli cells only syndrome in 22 (31.4%) and maturation arrest at the spermatocyte/spermatid level was seen in 13 (18.4%) patients. There were eight (10.2%) cases with scant smears where cytological diagnosis could not be made. A good correlation between cytological smears and histological sections was found in 54 of 58 testes (93.1%) in which histopathological confirmation was available.
Conclusions:  Testicular FNA may be utilized as a first-line investigative modality in patients with azoospermia, provided the procedure is performed and interpreted by experts.     

Immunohistochemical studies of colorectal carcinoma with a monoclonal antibody against carcinoembryonic antigen

Immunoperoxidase localization of carcinoembryonic antigen (CEA) was performed on tissue sections of colorectal carcinoma using a monoclonal antibody (MAb) against CEA. CEA has been demonstrated in 20 out of 22 rectum carcinomas (90.9%), in all of 23 colonic carcinomas, in none of 4 hyperplastic polyps and in 2 out of 6 adenomatous polyps (33.3%). CEA was found more often, and the intensity of the staining was stronger in well-differentiated carcinomas than in moderately and poorly differentiated carcinomas. No correlation was found between the presence of CEA in colorectal carcinoma and the stages of the disease. The mean values of serum CEA in patients with colorectal carcinoma and polyps with negative, weakly and strongly positive staining were 5.4 +/- 3.9 ng/ml, 28.3 +/- 23.8 ng/ml and 99.8 +/- 145.3 ng/ml respectively. Elevation of serum CEA occurred in 30 out of 39 (78.9%) cases with strongly positive CEA staining, in 4 out of 6 (66.7%) with weakly positive and in 1 out 9 (11.1%) with negative staining. A significant difference was found in serum CEA activity between the group with negative CEA staining and positive CEA staining (P less than 0.01). Our results suggest that the monoclonal antibody (MAb C27) can be used for the localization of CEA in conventionally prepared tissues of colorectal carcinomas by immunoperoxidase techniques for routine immunopathological diagnosis.     

Aberrant expression of a fetal glycoprotein 68 in hepatocellular carcinoma: a comparative study on the expression of alpha-fetoprotein and carcinoembryonic antigen

A rat IgG2a monoclonal antibody against a stage-specific fetal glycoprotein with a molecular mass of 68 kDa (FGP68) was produced and applied to paraffin sections. This monoclonal antibody was used to compare the expression of FGP68 with that of both alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) in 75 hepatocellular carcinomas (HCCs). Seventy-five primary HCCs from patients aged 36 to 77 years were examined. Formalin-fixed, paraffin-embedded tissue sections were used for immunohistochemical analyses. Histologically, 6 cases of HCC were classified as type I according to the Edmondson and Steiner criteria, 57 cases as type II, and 12 cases as type III. The cancer tissues showed positive reactions with the antibody against FGP68. Approximately one-third of the HCCs (26/75) contained tumor cells that expressed FGP68 -(21/57 for Edmondson and Steiner type II; 4/12 for type III; and 1/6 for type I) - and positive immunoreactivity was observed in the cytoplasm of the cancer cells. Twenty-five of the 75 HCCs had tumor cells that expressed AFP and there was a significant correlation between FGP68 expression and AFP expression. Twenty-three of the 75 HCCs had tumor cells that expressed CEA and there was no significant correlation between FGP68 expression and CEA expression. No positive reactions for FGP68, AFP and CEA were observed in samples of non-neoplastic liver tissues. Based on the possibility that stage-specific FGP68 plays an important role in liver embryogenesis, FGP68-expressing tumor cells might ontogenetically revert to more primitive cells.     

Cervicovaginal and endometrial cytology in ovarian cancer

The clinical significance of cytologic examination was studied in 114 patients with ovarian cancer who had received preoperative cytologic examinations. The overall positive rate of the cytologic examinations was 26.3% (30 of 114): 22 (19.3%) of the 114 cases had positive cervicovaginal smears while 13 of 31 endometrial aspiration smears (41.9%) were positive. The positive rate was not related to the volume of ascites but rather to its presence or absence. Thus, if ascites was observed, the positive rate was about 2.1 times higher than if it was absent. In two of four cases of ovarian cancer with no endometrial invasion but a positive cytologic examination of ascitic fluid, fallopian tube specimens contained cancer cells; this suggests that ovarian cancer cells may reach the cervix and/or vagina by passing through the fallopian tube, particularly if ascites is present. Since cytologic examination, especially of endometrial aspiration smears, shows a high positive rate if ovarian cancer cells are observed in the abdominal cavity, cytology should be used as an important ancillary method for the assessment of ovarian cancer.     

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.     

Comparison of DNA ploidy and nuclear size, shape and chromatin irregularity in tissue sections and smears of prostatic carcinoma

Image analysis measurements of nuclear size, shape, texture and DNA ploidy were compared in smears versus the corresponding 4-microns tissue sections, both prepared from radical prostatectomy specimens obtained from resections for prostatic cancer. Thirty-nine cases (78%) showed concordant DNA histograms between the smear and the tissue section. In six cases (12%), both preparations were nondiploid, but a tetraploid population was also present in one, but not both, of the preparations. In five cases (10%), there was a major discordance between the smear and the tissue section, with one preparation diploid and the other nondiploid. One source of discrepancy between the smear and tissue histograms was the overlapping of larger nuclei in tissue sections, which often precluded the analysis of the most atypical cells. Some tissue histograms were difficult to interpret due to wide coefficients of variation, irregular peaks and some shift from 2n in the diploid peaks. The best morphometric correlation (0.78) between the smears and the tissue sections was for the modal nuclear shape. Nuclear size and texture measurements showed poorer correlations. These findings suggest that cytologic preparations of prostatic carcinoma should be preferred for image analysis.     

Hepatocellular carcinoma versus carcinoma metastatic to the liver. Value of stains for carcinoembryonic antigen and naphthylamidase in fine needle aspiration biopsy material

Staining for amino acid naphthylamidase and carcinoembryonic antigen (CEA) was examined as an ancillary technique to improve the accuracy of differentiating hepatocellular carcinoma from metastatic carcinoma to the liver in fine needle aspiration (FNA) biopsy specimens. Twenty-four cases of FNA specimens from the liver, in which air-dried smears and/or cell blocks were available, were examined. Naphthylamidase-positive bile canalicular structures were present in 2 cases of hepatocellular carcinoma and absent in 8 cases of metastatic carcinoma studied. Ninety percent of the hepatocellular carcinomas were immunoreactive with the antibody to CEA, showing a predominantly bile canalicular pattern. Ninety percent of the cases of metastatic carcinoma were positive with the antibody to CEA, showing a diffuse cytoplasmic pattern. These findings indicate that both staining techniques may be useful in differentiating hepatocellular carcinoma from metastatic carcinoma. Since the naphthylamidase stain requires air-dried smears, which may not be available, whereas immunocytochemistry can be done on fixed material, the latter technique is more practical.     

Fine needle aspiration biopsy in the diagnosis of tuberculosis

Bacteriologic data and aspiration smears obtained by fine needle aspiration (FNA) biopsy for a series of 39 cases of tuberculosis were reviewed. Based on the morphologic features of the aspiration smears, the cases were divided into two groups: 18 cases in which distinct epithelioid granulomas were present and 21 in which no granulomas were found but large amounts of necrotic debris with variable numbers of polymorphonuclear cells, histiocytes and lymphocytes were present. Material from the FNA biopsy specimen was submitted for culture and fluorescence studies in 34 cases (15 with and 19 without granulomas). In the first group, auramine-rhodamine staining of smears was positive in 4 of 15 cases and Mycobacterium tuberculosis was isolated in 12 of 15 cases. In the second group, auramine-rhodamine staining was positive in 9 of 19 cases and culture was positive for M. tuberculosis in 16 of 19 cases. The results indicate that studying FNA smears by light microscopy and bacteriologic culture is an effective way of diagnosing tuberculosis.     

Histochemical demonstration of CEA in pathology of the colorectum

The evaluation of CEA serum levels and CEA tissue staining is one of the most common parameters used to help in the diagnosis and prognosis of colon-rectum disease. To this aim, an immunohistochemical demonstration of the CEA was carried out with the ABC staining system in sections of normal and diseased colon. 24 patients with polyps of the large intestine, 17 with rectocolitis, 22 with colon-rectum cancer and 11 normal subjects were studied. Results were positive in 9, 1% of the normal mucosa, 37, 5% of the polyps, 41, 2% of the rectocolitis and 100% of the carcinomas. However, the CEA in the positive reactions showed different degrees of staining and different cellular localization. From our results it would appear that the intracellular localization of this marker is connected with the degree of atypia in the histological sections. Immunohistochemical localization of the CEA could therefore be useful, above all in assessing the prognosis of colon-rectum disease.     

Liquid-based vs. conventional smears in fine needle aspiration of bone and soft tissue tumors

OBJECTIVE: To compare the accuracy of fine needle aspiration cytology of bone and soft tissue tumors utilizing ThinPrep (TP) (Cytyc Corporation, Boxborough, Massachusetts, U.S.A.) vs. conventional smears (CS). STUDY DESIGN: Fine needle aspiration cytology from bone and soft tissue tumors was processed and assessed for cellularity, nuclear and cytoplasmic preservation, cellular architecture and stromal background with both the TP liquid-based smear technique and conventional methods. RESULTS: An accurate diagnosis was made in 13% of TP cases as compared to 64% in CS cases. CONCLUSION: CS of fine needle aspiration sample is far superior to TP in diagnosing tumors of bone and soft tissues. Preservation of cytoplasmic features and cellular architecture was superior in conventionally prepared smears.     

Cytodiagnosis of 112 salivary gland lesions. Correlation with histologic and frozen section diagnosis.

Aspirates of 112 cases of salivary gland lesions with histologic correlation were reviewed. Fifty-five cases (49%) had frozen sections made. The 112 cases included 76 cases of benign lesions (31 cases of pleomorphic adenoma, 19 of Warthin's tumor and 26 of nonneoplastic lesions), 22 of primary salivary gland malignancy and 14 of metastatic malignant lesions. The overall accuracy in diagnosing benign and malignant lesions was 95%. The accuracy in diagnosing the exact category of neoplastic lesions was 70%. The diagnostic sensitivity for malignant lesions was 86% and the specificity, 99%. There was one false positive, in which a pleomorphic adenoma was diagnosed as small cell carcinoma. Five false-negative cases were encountered that were due to underdiagnosis of mucoepidermoid carcinoma and adenoid cystic carcinoma. The smears were reviewed, and the diagnostic pitfalls are discussed. A comparison of the cytodiagnosis and frozen section diagnosis was made. In frozen sections there were two false negatives, and two diagnoses were deferred. The overall diagnostic accuracy was 91%. The accuracy in diagnosing the exact category of neoplastic disease was 77%. The diagnostic sensitivity for malignant disease was 70% and specificity, 100%. Frozen section, however, did supplement the fine needle aspiration diagnosis in 13 cases.     

Cytodiagnosis of endometrial malignant mixed mesodermal tumor

The accuracy of endometrial aspiration smears obtained with the Isaacs cell sampler in the diagnosis of malignant mixed mesodermal tumors (MMMT) was compared to the results obtained with routine cervical and vaginal smears in five cases of MMMT found in a series of 220 endometrial aspirations. Cervical and vaginal smears previously taken on these patients were positive for adenocarcinoma or MMMT in two cases and suspicious for adenocarcinoma in the remaining three cases. Endometrial aspirates were positive for MMMT in three cases and positive for adenocarcinoma or MMMT in two cases. The endometrial aspiration smears contained a variety of cells: malignant glandular, squamous, spindly stromal, undifferentiated, osteoid and tumor giant cells; chondrocytes and free psammoma bodies were also observed. These cases indicated that endometrial aspiration can accurately detect the heterologous cellular elements found in MMMT and is an effective technique in its diagnosis.     

Adult-type rhabdomyoma of the palate. Cytologic presentation of two cases with histologic and immunologic study

The cytologic presentations of two adult-type rhabdomyomas of the soft palate are reported. Fine needle aspiration smears of the lesions contained globular tumor cells that had striations and intracytoplasmic rod-shaped inclusions. These inclusions, corresponding to hypertrophied Z bands, were pathognomonic of rhabdomyoma tissue. The cytologic diagnosis was confirmed by histologic and immunologic studies in both cases. The cytologic preparations fixed in alcohol or air dried did not show the "spiderweb cells" observed in the histologic sections of tissue fragments fixed in formaldehyde; this clearly illustrates that the morphology of the cells of this tumor depends primarily on the specimen preparation technique used. These cases suggest that aspiration cytology can establish the diagnosis of this benign tumor of striated muscle, for which total surgical removal is usually sufficient to effect a cure. The differential diagnosis is discussed in detail.     

Transthoracic needle aspiration biopsy. Review of 233 cases

In 233 cases in which transthoracic needle aspiration was done at the Mayo Clinic from 1980 through 1983, the cytology slides, tissue fragments and patient histories were reviewed; the original and review diagnoses were compared and correlated with the subsequent clinical course. In most cases, the procedure was performed with an 18-gauge needle under fluoroscopic guidance, primarily in cases with suspected malignant masses that were considered to be not surgically resectable. In 70% of the cases, there was a history of malignancy, and 82% of the malignant lesions were of extrapulmonary origin. Correlation of the original diagnosis with the clinical course yielded 70% (164 cases) true positives, 6% (14 cases) true negatives, 16% (37 cases) false negatives, 0% false positives and 8% (18 cases) indeterminants. In none of the false-negative cases was the slide subsequently read as positive in a blind review. Of the true-positive cases, 12% had positive tissue fragments only, 37% had positive cytology smears only, and 51% had both positive smears and fragments. In 32% of the cases, there were radiologically demonstrable pneumothoraces, and in 12%, placement of a chest tube was required. Hemoptysis occurred in less than 5% of the cases. In summary, transthoracic needle biopsy provides an efficient way to accurately obtain diagnostic tissue, with acceptable minor complications.     

Immunocytochemical detection of Ki‐67 in Diff‐Quik‐stained cytological smears of canine mammary gland tumours

U.S. Choi and D.Y. Kim Immunocytochemical detection of Ki‐67 in Diff‐Quik‐stained cytological smears of canine mammary gland tumours Objective: To investigate whether Diff‐Quik stained fine needle aspirate smears can be used to evaluate Ki‐67 expression by immunocytochemistry. Methods: Both cytological and histological samples were obtained from 24 dogs with spontaneously developed mammary gland tumours. The cytological and histological specimens were examined by Diff‐Quik and H&E stains, respectively. After examination, both samples were immunostained using the same Ki‐67 antibody. The % Ki‐67 values were calculated based on the percentage of positively stained tumour cells per 500 and 1000 tumour cells in cytology and histology specimens, respectively. Results: Ki‐67 staining was successful in 17/24 smears (71%) and 19/23 sections (83%). The correlation coefficient between the percentage of Ki‐67‐positive cells in cytological smears and in the histological sections was 0.677 (P < 0.01). These values were significantly different between histologically benign and malignant tumour groups both in cytology and histology samples (P < 0.001). The threshold value of the percentage of Ki‐67‐positive cells for distinguishing benign from malignant tumours was set at 4.85% with 90.9% sensitivity and 92.3% specificity by Receiver Operating Characteristic (ROC) curve using histopathology as the gold standard. Conclusion: Diff‐Quik‐stained cytology smears can be used to detect the presence of Ki‐67 antigen when histology sections are not available.     

Mastopathic fibroadenoma of the breast: a pitfall of aspiration cytology

OBJECTIVE: To assess the correlation between cytological diagnoses and histological subtypes of fibroadenoma (FA) and to clarify the cytological features of a specific group of FA displaying variable features similar to fibrocystic disease (mastopathic type, MFA), and to evaluate the significance of this subtype in cytological diagnosis. METHODS: A review of 141 cases of histologically proven FA was performed. We re-classified them into four subtypes according to Kinoshita's criteria [Jpn J Breast Cancer6 (1991) 377] and further selected 92 cases for which both fine needle aspiration (FNA) smears and histological specimens were available. Among them, 18 cases of MFA and their cytological smears were selected for the present study. RESULTS: There was significant correlation between MFA and cytological diagnosis of 'indeterminate' or 'suspicious for malignancy' (P < 0.01). Although no false-positive diagnosis was experienced in our series, 56% of the MFAs (10/18) had cytological diagnoses of indeterminate or were included in the category 'suspicious for malignancy'. Smears from MFA revealed high cellularity (9/18 smears had more than 10 epithelial clusters each composed of more than 50 cells), presence of cellular discohesiveness (13/18, 72.2%), but only mild nuclear atypia (5/18, 27.8%). Anisonucleosis was present in fewer than half the cases and no apparent condensed chromatin was identified. CONCLUSION: We highlight the significance of subclassification of MFA in aspiration cytology of breast. MFA had a significantly higher chance of falling into the 'suspicious for malignancy' or 'indeterminate' diagnostic category in aspiration cytology. It might be a diagnostic challenge for cytopathologist to identify this subtype of FA in FNA smears.     

Nuclear grooves in the aspiration cytology of papillary carcinoma of the thyroid

Nuclear grooving has recently been shown to be a useful morphologic feature in the diagnosis of papillary carcinoma of the thyroid in tissue sections and imprint smears. In order to assess the diagnostic value of nuclear grooving in cytologic specimens, the presence of this feature was evaluated in fine needle aspirates from 20 papillary carcinomas of the thyroid, 10 follicular adenomas, 3 follicular carcinomas, 1 medullary carcinoma, 10 nodular goiters and 4 cases of Hashimoto's thyroiditis. In each case, 30 random high-power fields (HPFs), or all fields in less cellular smears, were examined, and the percentage of the fields in which nuclear grooving could be seen was recorded. Seventeen of 20 papillary carcinomas (85%) showed nuclear grooves in more than 25% of the HPFs examined; in the remaining three cases, grooves were observed in less than 25% of the HPFs. In control cases (all other thyroid lesions), nuclear grooves either were absent or were present in less than 25% of the HPFs examined. These findings suggest that nuclear grooving, when seen in abundance, can be considered a reliable criterion for the diagnosis of papillary carcinoma in fine needle aspiration cytology of the thyroid. The presence of occasional grooves, however, should be regarded as a nonspecific finding.