Combined morphometrical and syntactic structure analysis as tools for histomorphological insight into human lung carcinoma growth

Histological sections of formalin-fixed, paraffin-embedded tissue comprising 60 surgical specimens of human lung carcinoma were Feulgen stained. The histomorphological images were transferred to an automated image analysing system (VISIAC) and analysed as follows. The geometrical centers of tumor cell nuclei were defined as vertices, and the minimum spanning tree (MST) was calculated based on the two-dimensional distance between the vertices. Segmentation of the images was performed semiautomatically by interactive definition of nuclei of interest and automated detection of nuclear boundaries. Several morphometric features of tumor cell nuclei were measured including size, DNA-content (extinction), and form factor, and were set in relation to parameters of the MST. The following results were obtained: DNA-content and tumor cell nucleus size ('center cell') of different microscopic tumor growth patterns are related to the number of nearest neighboring cells. No relation was found in the neighboring (surrounding) cells. The different cell types of lung carcinoma, i.e., the different microscopic tumor textures expressed the relation of center cell features to the parameters of MST. A high amount of DNA content in branching points of the MST for epidermoid carcinoma may be interpreted as carcinoma growing in epidermoid textures tend to proliferate from tumor cell nuclei related to at least one neighboring cell. The opposite was found for large cell anaplastic carcinoma (no perceptible microscopic textures of the tumors) which showed the highest DNA content in tumor cell nuclei but which was not related to any neighboring cells. This technique allows analysis of growth centers and microenvironment conditions in human lung cancer in relation to tumor texture at the light microscopy level.     

Flow cytometric analysis of human lung cancer. Correlation with histologic type and stage

DNA ploidy and cell-cycle characteristics of 65 operable lung cancers (41 adenocarcinomas, 19 epidermoid carcinomas, 3 large-cell carcinomas and 2 small-cell carcinomas) were analyzed using flow cytometry. Eighty percent of the tumors were aneuploid. The mean DNA index was lower in epidermoid than in adenocarcinoma. In adenocarcinoma, a low DNA index was correlated with early-stage disease; no correlation between DNA index and stage was observed in the other cell types. The %S-phase cells was highest in two cases of undifferentiated large-cell carcinoma and lowest in adenocarcinoma. The RNA index was increased approximately two-fold in all cell types. Longer follow-ups will be required to establish any correlation between the cell kinetic measurements reported here and survival times.     

Classification of lung carcinoma by means of digital nuclear image analysis

An investigation was performed of the maximum discriminating efficiency for each subgroup of digital nuclear image features and of the overall classification of nuclei from three types of human lung carcinomas in histologic sections: adenocarcinoma, small-cell carcinoma and squamous-cell carcinoma. The results indicate that, for each subgroup of features, the nuclei of the small-cell carcinomas are generally "correctly" classified in a higher percentage (80% to 100%) than are the nuclei of the adenocarcinomas (46% to 74%) and squamous-cell carcinomas (29% to 68%). The discriminant analysis for the overall classification selected features from most of the subgroups, suggesting that it is useful to perform nuclear image analysis with many subgroups having different properties. The overall classifications for the nuclei of the adenocarcinomas, small-cell carcinomas and squamous-cell carcinomas were, respectively, 81.4%, 93.2% and 74.7%. Before this technique can be applied to histopathologic diagnosis, a larger number of unselected lung carcinomas must be evaluated.     

Factors significant in the diagnostic accuracy of lung cytology in bronchial washing and sputum samples. I. Bronchial washings

Some factors influencing the diagnostic accuracy for primary lung cancer in bronchial washings were studied in 276 consecutive cases seen between 1959 and 1974. Diagnostic accuracy increased during the years under study; the reasons included increasing expertise of the laboratory staff, better documentation of cytologic criteria and improved collection techniques. The overall accuracy was 74%. Detection of malignant cells was highest for squamous-cell and adenosquamous carcinomas (81%), small-cell carcinoma, adenocarcinoma and large-cell carcinoma (70%) and lowest for bronchioloalveolar-cell carcinoma (47%). Accuracy was 84% for central tumors as compared to 30% for peripheral lesions. Tumors of less than 2 cm in diameter yielded very poor results (15%) while those greater than 2 cm yielded 82% accuracy. The specificity of diagnosis of cell type in those specimens with malignant cells was over 93% for squamous-cell carcinoma, small-cell carcinoma and adenocarcinoma, 77% for large-cell carcinoma and below 50% for adenosquamous carcinoma, bronchioloalveolar carcinoma and the uncommon tumors. Two bronchial washings per case gave an appreciably better result (92%) than one per case (68%). The percentage of unsatisfactory specimens from those with cancer was 13.5 and from a control group was 29.9. Reasons for unsatisfactory specimens included limited cellular material, excessive blood and/or leukocytes and drying artifacts.     

Dry mass, DNA and non-histone protein determinations in lung cancer cells

Summary Cell nuclei from two biopsies of bronchial mucosa, seven squamous-cell carcinomas and six small-cell carcinomas of the lung were investigated. DNA and non-histone protein (NHP) content were simultaneously determined in Feulgen—Naphthol Yellow S-stained smears by means of multiple plug cytophotometry. In addition, the nuclear dry mass of cells originating from the same populations was measured by interference microscopy.DNA histograms of carcinomas were characterized by DNA stemlines being situated in the diploid range in four out of six small-cell carcinomas and in the hyperdiploid to hypertetraploid range in six out of seven squamous-cell carcinomas.Polyploid values (up to 8 c) were seldom found in small-cell carcinomas whereas squamous-cell carcinomas showed a broader dispersion approaching the 16 c level.The similarity of the NHP distributions with the DNA histograms was more marked in small-cell carcinomas than in the squamous-cell carcinomas. In comparison with the NHP distributions of normal bronchial epithelial cells, those of carcinomas were shifted to higher values. The increased NHP content was found to be a more prominent sign of malignancy in small-cell carcinomas than the DNA mass. The increase in nuclear dry mass in carcinomas was mainly caused by the accumulation of NHP in tumour cell nuclei.     

Nuclear DNA content, cytomorphologic features and clinical characteristics of small cell carcinoma of the lung

The relationship between the cytomorphologic features, the nuclear DNA patterns and the clinical prognosis of patients with small cell carcinoma of the lung was studied. In cases in the long-survival group (greater than or equal to 24 months), bronchial brushing smears contained a relatively high frequency of nuclei with large, irregular shapes and finely granular chromatin patterns, in comparison with patients in the short-survival group (less than or equal to 9 months); the correlation was not statistically significant, however. The incidence of cells with round or oval nuclei and finely granular chromatin patterns was higher in patients whose cells had hyperdiploid DNA patterns than for patients whose cells had near-diploid patterns; again, the difference was not statistically significant. Patients whose tumor cells had hyperdiploid DNA patterns had significantly shorter survival times than did patients whose tumor cells had near-diploid patterns. These results indicate that (1) judging the nuclear DNA pattern from the cytomorphologic features of small cell carcinoma is unreliable and (2) the nuclear DNA patterns are related to the clinical prognosis of patients with small cell carcinoma of the lung.     

Cytomorphology of the variants of small-cell carcinoma of the lung

Cytologic classification of subtypes of small-cell carcinoma of the lung (SCCL) was retrospectively performed on respiratory material of 90 cases of lung carcinoma cytologically diagnosed as SCCL. Additionally, the cytologic material was reexamined for the presence of variants of SCCL in 68 cases of lung carcinoma whose types had not been conclusively defined by cytology. The type of lung cytology specimens reviewed were sputa, bronchial washings and brushings and fine needle aspirations. The study included review of pretreatment tumor histology, when present, and examination of the ultrastructure of the tumor in selected cases whose type had not been well defined by histology. Subtype recognition depended on the adequacy of the specimens rather than on the type of cytologic material examined. The cytologic subtyping was generally in agreement with the histologic subtyping of the tumor, except for cases in which SCCL was combined with other types of lung carcinoma, where certain discrepancies were noted.     

Automated cytopathologic diagnosis of bronchial carcinoma. II. Preliminary results of classifying cytocentrifuged bronchial brushings

An automated discrimination between healthy and neoplastic bronchial cells was performed on eight bronchial smears prepared by cytocentrifugation. An image analyzer was used to examine 415 cells in these smears. The nuclear surface of each cell was measured, as was the total integrated optical density for 25 programmed thresholds. The results show that it is possible to distinguish healthy from cancerous cells in a given subject using these two measured parameters and two new parameters deduced mathematically. It appears difficult, however, to demonstrate a typical healthy and typical cancerous bronchial cell that could be used as a reference for all subjects. It is thus the presence of cell heterogeneity in a given subject that enables him or her to be characterized as healthy or having cancer.     

Regional heterogeneity of EGFR gene amplification and nuclear morphology in glioblastomas. An investigation using laser microdissection and pressure catapulting

OBJECTIVE: To study the regional heterogeneity of epidermal growth factor receptor (EGFR) gene amplification (EGFR-GA) in glioblastomas, considering the relationship between this mutation and morphology of tumor cell nuclei. STUDY DESIGN: Tissue samples gained by laser microdissection and pressure catapulting were used for the performance of differential polymerase chain reaction in 32 morphologically different regions from 7 glioblastomas. Semiquantitative determination of EGFR expression and image analysis of tumor cell nuclei were performed in the same regions. RESULTS: Distinct regional differences concerning the degree of EGFR-GA were found in 2 tumor cases. When comparing regions with different degrees of gene amplification within these cases, morphologic differences in tumor cell nuclei were observed. The other tumor cases also showed distinct intratumoral heterogeneity concerning histomorphology but no regional heterogeneity in the degree of EGFR-GA. When comparing regions with a low densitometric EGFR/interferon (INF) band ratio (< 2.19, n = 18) and a high EGFR/IFN band ratio (> 4.39, n = 14), the latter type of region showed a significantly higher percentage of Ki-67--positive tumor cell nuclei and lower values for several shape variables (Fourier amplitudes), indicating a tendency toward a more regular nuclear shape in regions with distinct EGFR-GA. For the EGFR/IFN band ratio, a significant correlation was found with several morphometric variables, especially those of nuclear shape and distances between nuclei. CONCLUSION: In glioblastomas showing regional heterogeneity in the degree of EGFR-GA, morphology of tumor cell nuclei has been shown to be different when comparing regions with different degrees of EGFR-GA. Glioblastomas may also show distinct regional heterogeneity of histomorphology without evidence of regional heterogeneity of EGFR-GA. A significant statistical association has been confirmed between the degree of EGFR-GA and quantitative morphology of tumor cell nuclei.     

Roundness of epithelial nuclei in bronchial mucosa

OBJECTIVE: To estimate the shape of epithelial nuclei in bronchial mucosa. STUDY DESIGN: Bronchoscopic mucosal samples from 12 patients with chronic bronchitis and 14 patients with squamous cell bronchial carcinoma were routinely processed and stained with the hematoxylin and eosin method. Fields with stratification and squamous metaplasia were selected. The roundness of epithelial nuclei was estimated using Lucia, version 3.51 ab, with an objective of 40:1 (NA = 0.65) and final magnification of 1,900:1. The images were manually edited. Roundness was calculated from area and perimeter. RESULTS: The mean roundness in stratification and squamous metaplasia in bronchial mucosa from carcinoma patients (0.90 +/- 0.04) was significantly greater than in bronchial mucosa from chronic bronchitis patients (0.80 +/- 0.006) (P < .05). CONCLUSION: Our results indicate that cell nuclei in stratification and squamous metaplasia in patients without bronchial cancer are more elongated than nuclei found under the same conditions in patients with squamous cell carcinoma.     

Cytology of bronchial benign granular-cell tumor

The cytologic features of a case with multiple bronchial benign granular-cell tumors are reported and compared with those of previously reported cases. Characteristic tumor cells were found in the bronchoscopic brushing smears and in cell block sections (but not smears) prepared from the washing fluid. These findings were confirmed by the bronchial biopsy and histologic study of the resected tumors. A cytologic diagnosis of bronchial granular-cell tumor should not be difficult because the cytologic appearance of the tumor cells is characteristic; however, the possibility of a concomitant tumor, such as adenocarcinoma or small-cell carcinoma, should be considered and excluded.     

Tumors of the respiratory tract observed at the German Primate Center, 1978–1994

Abstract: Eight spontaneous pulmonary tumors (four bronchiolar tubular adenomas, two bronchiolar adenocarcinomas, two squamous-cell carcinomas) occurred in a total of 54 adult tree shrews (Tupaia belangeri) of the GPC colonies between 1978 and 1994. The adenomas and adenocarcinomas consisted of tubularly or trabecularly arranged cuboidal to cylindrical cells interspersed with some PAS-positive goblet cells, thus resembling the epithelial lining of respiratory bronchioles of tree shrews. The two squamous-cell carcinomas probably originated from the pulmonary alveoles. Three more pulmonary tumors (one small-cell carcinoma, one bronchial adenoma, one squamous-cell carcinoma) developed in 409 adult callitrichids of the GPC colonies during the same period, and one more bronchial adenoma was observed in a common marmoset (Callithrix jacchus) of another colony located in Göttingen. With regard to the adenomas and squamous-cell carcinomas, a similar cellular origin with the tree shrews is assumed. The small-cell carcinoma possibly developed from the bronchial epithelium, provided a pathogenesis parallel to that of human small-cell carcinoma is suggested. Four of the tree shrew pulmonary adenomas/adenocarcinomas and the small-cell Ca were macroscopically visible as yellowish-grey nodules of 1 mm × 1 mm to 15 mm × 15 mm diameter, predominantly involving the main lobes (2 × right main lobes, 2 × left main lobes, 1 × all lobes). The pulmonary tumors of the other animals were below macroscopical detectability.     

Relationship of CA 125 and CA 19.9 with lung carcinoma histological subtype: preliminary study

The aim of this work was to study the possible utility of simultaneous determination of CA 125 and CA 19.9 in patients with lung cancer. Serum levels of both markers were studied in 87 patients without metastases (Mo), 72 patients with distant metastases (MT) and 15 cases without clinical evidence of disease after primary treatment (NED). Sixty-five tumors were epidermoid, 34 were adenocarcinomas, 24 were cell undifferentiated carcinomas and 51 were small-cell carcinomas. Sera from 75 healthy subjects and 20 patients with benign lung disease were used as controls. The cut-off values used were 35 and 37 U/ml for CA 125 and CA 19.9, respectively. CA 125 and CA 19.9 serum levels were within normal limits in all control patients. In NED patients these markers were not elevated, except in one with chronic liver disease who showed elevated CA 19.9 (76 U/ml). Twenty-five percent of Mo lung cancer patients and 40.3% of MT cases had CA 19.9 over 37 U/ml. Abnormally high levels of CA 125 were found in 18.7% and 22.9% of Mo and MT patients, respectively. Sixty percent of patients with large cell undifferentiated carcinoma had elevated CA 125 (mean 176 U/ml) compared to 15.4% of patients with all other histological types of tumors combined (54.3 U/ml, p less than 0.01). CA 19.9 serum levels were also more often elevated in patients with large cell undifferentiated carcinomas (50%, 7/14 cases) than in other histological types (30%, 36/120 patients), but the difference was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Factors significant in the diagnostic accuracy of lung cytology in bronchial washing and sputum samples. II. Sputum samples

Some factors influencing the detection of malignant cells in sputum samples were evaluated in 449 consecutive cases of primary lung carcinoma seen between 1959 and 1974. Diagnostic accuracy increased during the years under study; the reasons are discussed. The overall accuracy was 82.8%. Detection of malignant cells was 85% for small-cell carcinoma, squamous-cell carcinoma and large-cell carcinoma, 75% for adenocarcinoma, bronchioloalveolar carcinoma and adenosquamous carcinoma and 64% for the uncommon tumors. Accuracy was 87% for central tumors and 42% for peripheral lesions. Tumors less than 2 cm in diameter yielded only 39% accuracy as compared to 90% for larger tumors. The specificity of diagnosis of cell type in those specimens with malignant cells was 95% for small-cell carcinoma and squamous-cell carcinoma, more than 80% for adenocarcinoma and large-cell carcinoma, 65% for bronchioloalveolar-cell carcinoma and adenosquamous carcinoma and less than 30% for the uncommon tumors. Diagnostic accuracy was optimal in those cases with three or more sputum samples: 83% for those with three samples and 90% for those with five or more samples per case. The use of both sputum and bronchial specimens was complementary and increased the accuracy further. Reasons for unsatisfactory specimens included no deep cough, limited cellular material, excessive blood or leukocytes and drying artifacts; the first two were the most common causes.     

Association of glutathione S-transferase P1 gene polymorphism with the risk of small-cell carcinoma of lung cancer

Abstract

The conclusions of the published reports on the relationship between glutathione S-transferase P1 (GSTP1) gene polymorphism and the risk of small-cell carcinoma of lung cancer are still debated. GSTP1 is one of the important mutant sites reported at present. This meta-analysis was performed to evaluate the association between GSTP1 and the risk of small-cell carcinoma of lung cancer. The association investigations were identified from PubMed and Cochrane Library, and eligible studies were included and synthesized using meta-analysis method. Ten reports were included into this meta-analysis for the association of GSTP1 A/G gene polymorphism and small-cell carcinoma of lung cancer. The G allele and GG genotype were not associated with the susceptibility of risk of small-cell carcinoma in overall populations, East-Asians and Turkish population. However, there was an association between GG genotype with the risk of small-cell carcinoma in Caucasians. In conclusion, GG genotype was associated with the risk of small-cell carcinoma in Caucasian patients with lung cancer. However, GSTP1 A/G gene polymorphism is not associated with the susceptibility of small-cell carcinoma in overall populations, East-Asians and Turkish population.     

Utility of liquid-based cytology in endometrial pathology: diagnosis of endometrial carcinoma

Objective: The purpose of this study was to examine the utility of SurePath‐liquid‐based cytology (LBC) compared to conventional cytological preparations (CCP) in the identification of endometrial carcinoma. Methods: During a 13‐month period, direct endometrial samples were collected from 120 patients using the Uterobrush. The material comprised 30 cases each of endometrial carcinoma, proliferative endometrium, secretory endometrium and atrophic endometrium. The following points were investigated:(i) the frequency of cell clumps in endometrial carcinoma; (ii) the area of cell nuclei; (iii) overlapping nuclei. Results: (i) Comparison of the frequency of cell clumps with irregular protrusion pattern and papillo‐tubular pattern showed no statistically significant difference in either type of cell clump between CCP and LBC. (ii) Comparison of the nuclear area of cells showed a sequential decrease from endometrial carcinoma to secretory endometrium, to proliferative endometrium and to atrophic endometrium, which was significant in CCP and LBC. (iii) Nuclear area was significantly lower with LBC compared with CCP in endometrial carcinoma, secretory endometrium and proliferative endometrium but not atrophic endometrium. (iv) Comparison of the degree of overlapping nuclei showed a sequential decrease from endometrial carcinoma to proliferative endometrium, to secretory endometrium and to atrophic endometrium, which was significant in both CCP and LBC. (v) Comparison of the degree of overlapping nuclei between CCP and LBC showed no significant difference for normal types of endometrium, but LBC had significantly higher values (P < 0.0001) in endometrial carcinoma than in CCP. Conclusions: The results of this study revealed that applying diagnostic criteria used in CCP to LBC was easy to achieve, because LBC had excellent cytoarchitectural preservation and cells were well presented. Although we have not examined all cytological features of malignancy and have not considered atypical hyperplasia, we believe that this method may be a useful tool in the diagnosis of endometrial cytology.     

A morphologic and morphometric study of cells from colloid carcinoma of the breast obtained by fine needle aspiration. Distinction from other breast lesions

Morphologic and morphometric studies were carried out on eight cases of pure and mixed colloid carcinoma of the breast initially diagnosed by fine needle aspiration (FNA). Key morphologic features included (1) cellular smears, (2) single cells, loose aggregates and cohesive groups of cells bathed in a mucinous background, (3) single cells displaying nuclear eccentricity and (4) little variation in nuclear size or shape, with bland-to-accentuated chromatin and rare nucleoli. These morphologic features are compared with those observed in pregnancy adenoma, lobular carcinoma, fibroadenoma, ductal carcinoma and medullary carcinoma. A morphometric study employing the major and minor axes of the nucleus, its axis product and axis ratio was also performed. Statistical treatment confirmed that the nuclear axis product (a size factor) distinguished colloid carcinoma from the other breast lesions, except the small-cell type of ductal carcinoma. Furthermore, the nuclear axis ratio (a shape factor) discriminates pregnancy adenoma and small-cell ductal carcinoma from the other breast lesions studied. By combining morphologic and morphometric criteria, one can specifically separate colloid carcinoma from the other breast lesions when examining smears obtained by FNA. Since colloid carcinoma is usually composed of cells with a relatively benign-appearing cytomorphology, the importance of recognizing this entity in fine needle aspirates is emphasized.     

Detection of underlying characteristics of nuclear chromatin patterns of thyroid tumor cells using texture and factor analyses

BACKGROUND: Aspiration biopsy cytology of thyroid tumors has been used more frequently in recent times to differentiate between malignant and benign lesions. Chromatin patterns of the tumor cell nuclei are one of most important factors for cytologic diagnosis. The interpretation of nuclear chromatin patterns is subjective and more difficult than that of nuclear size or shape. In the present report, we investigated how to detect underlying chromatin characteristics of benign and malignant thyroid tumor cells by means of texture and factor analyses. METHODS: We employed a computer-aided system in which light microscopy was combined with an image processor and monochrome camera. Using this system, 100 randomly selected cells in a Papanicolaou stained, aspiration biopsy cytologic smear in each case of 39 benign and malignant thyroid tumor cases were digitized. We applied two-dimensional and higher texture analyses with the use of co-occurrence and run-length matrices to analyze the chromatin patterns. Factor analysis was used to determine whether a large number of independent variables actually measured one or more underlying common variables. RESULTS: According to parameters with high factor-loading values, the morphologic chromatin characters were classified into three categories according to heterogeneity, contrast, and homogeneity of chromatin patterns. On the basis of analyses with these morphologic categories, nuclei of papillary carcinoma showed higher contrast of chromatin patterns than did those of the benign group. Moreover, there was a variety of contrasting chromatin patterns among cells in each papillary carcinoma case in comparison with the benign group. In contrast, follicular carcinomas showed a significant difference in the standard deviation of factor 3, which indicated more monotonous chromatin patterns among cells in each follicular carcinoma case than in each benign case. CONCLUSION: We believe that this technique, using texture and factor analyses, is useful in the detection of underlying characteristics of nuclear chromatin patterns in aspiration biopsy cytology.     

The cytodiagnosis of well-differentiated neuroendocrine carcinoma. A distinct clinicopathologic entity

Well-differentiated neuroendocrine carcinoma (WDNE) has been recognized as a distinct variant of pulmonary neuroendocrine carcinoma, with characteristic histopathologic and clinical features that separate it from both carcinoid and small-cell carcinoma (SCC). Histologic review of tumors in long-term survivors (greater than two years) with an initial diagnosis of SCC has shown that the majority of these cases are, in fact, better classified as WDNE; the distinction of WDNE from SCC has, therefore, important prognostic and therapeutic implications. A retrospective review of 200 cytologies originally diagnosed as SCC was undertaken in an attempt to characterize the cytomorphologic features of WDNE. The cytologic criteria that distinguished cases of WDNE included polygonal-to-fusiform cells with a variable amount of lacy cytoplasm, oval nuclei with coarsely dispersed chromatin and frequent chromocenters, and mild nuclear and cytoplasmic anisomorphism. The majority of malignant cells were arranged either in acinarlike clusters or in epithelial sheets with evidence of palisading. Twenty-two cases were reclassified cytologically as WDNE and were accurately distinguished from all other neoplastic and SCC cases on repeated double-blind review. Clinical and histologic data confirmed the diagnosis of WDNE in all cases; it can be concluded that SCC and SDNE are cytologically distinct entities.     

Cytology of basaloid squamous carcinoma of the bronchus. A case report

BACKGROUND: The cytologic appearance of basaloid squamous carcinoma (BSC) arising in the lower respiratory tract has not been described very well because of its rarity. This article describes a surgical case of bronchial BSC and provides the first documentation of the sputum and imprint cytologic features of the tumor. CASE: A 74-year-old man presented with hemoptysis. An abnormal intrabronchial mass was revealed by computed tomography and bronchoscopy. Preoperative cytology and biopsy showed that the mass was composed of small, round, atypical cells, but correct diagnosis was difficult. Under a tentative diagnosis of small round cell carcinoma, a right lobectomy was performed. The resected tumor was composed of small cells showing peripheral palisading and partial epidermoid differentiation. There was no glandular differentiation. Focal necrosis was also noted. Immunohistochemical markers for smooth muscle and neuroendocrine cells were negative. The tumor was eventually diagnosed as BSC or basaloid carcinoma (BC) with squamous differentiation. CONCLUSION: It is important to recognize this disease, especially when undetermined small round cell carcinoma is noted in cytologic specimens, in order to properly assess prognosis. Cytologic detection of nuclear palisading of the neoplastic cells, one of the hallmarks of the disease, may be difficult, however, careful examination to reveal neoplastic cells showing squamous differentiation appears helpful for diagnosis.