The Risk Factors Influencing between the Early and Late Recurrence in Systemic Recurrent Breast Cancer.

PURPOSE: Patients with recurrent breast cancer usually die of their disease, even after radical surgery and adjuvant therapies which could reduce the odds of dying. Many studies analyzed and compared patients who died of recurrent disease with those that died without recurrent disease. However, less attention has been paid to evaluating factors associated with the timing of recurrence. Thus, the objective of this study is to investigate the correlation between various factors and the timing of recurrence. METHODS: We retrospectively reviewed the data of 95 recurrent breast cancer patients who underwent curative surgery to determine the prognostic factors such as menopausal status, operation method, stage, nodal status, histologic grade, nuclear grade, extensive intraductal carcinoma component, hormone receptor, p53, c-erbB-2, Ki-67, and molecular subtype. We had attempted to compare the recurrent patients within 2 years after operation and adjuvant chemotherapies as the early recurrence with those over 2 years as the late recurrence. RESULTS: Histologic grade (p=0.005), nuclear grade (p<0.001), p53 (p=0.022), and Ki-67 (p<0.001) were significant different factors that influenced the systemic recurrence between early recurrence and late recurrence. In stage I/II, histologic grade (p=0.001), nuclear grade (p<0.001), and Ki-67 (p=0.005) were significant factors that influenced the systemic early recurrence. In stage III, nuclear grade (p=0.024), and Ki-67 (p=0.001) were significant factors that influenced the systemic early recurrence. But subtypes (p=0.189, p=0.132, p=0.593, p=0.083) are not associated with the timing of recur rence. CONCLUSION: In systemic recurrent breast cancer patients, the risk factors such as histologic grade, nuclear grade, p53 and Ki-67 are also associated with the timing of recurrence. We sug gest that these patients should be proper treated and be closely followed up.

Role of fine needle aspiration cytology, cell block preparation and CD63, P63 and CD56 immunostaining in classifying the specific tumor type of the lung.

OBJECTIVE: To determine whether CD63, p63 and CD56 are useful in the diagnostic evaluation of cytologic samples of pulmonary malignancy. STUDY DESIGN: We explored the utility of using a panel of 3 antibodies, CD63, p63 and CD56, for the diagnosis of lung cancer in cytologic samples consisting of 40 cases of cell block sections and previously Papanicolaou-stained cytologic smear slides. RESULTS: The positive rates for CD63, p63 and CD56 were as follows: adenocarcinoma (18/19), (0/19), (0/19), for small cell lung carcinoma (3/8), (0/8), (8/8), and for squamous cell carcinoma (0/13), (12/13), (0/13). All p63 positive cases were squamous cell carcinoma, and all CD56 positive cases were small cell lung carcinoma. CD63 was positive in the majority of adenocarcinomas. CONCLUSION: The panel of CD63, p63 and CD56 appears to be useful in the diagnostic evaluation of cytologic samples of pulmonary malignancy.

Clinical implication of recurrent copy number alterations in hepatocellular carcinoma and putative oncogenes in recurrent gains on 1q.

To elucidate the pathogenesis of hepatocellular carcinoma (HCC) and develop useful prognosis predictors, it is necessary to identify biologically relevant genomic alterations in HCC. In our study, we defined recurrently altered regions (RARs) common to many cases of HCCs, which may contain tumor-related genes, using whole-genome array-CGH and explored their associations with the clinicopathologic features. Gene set enrichment analysis was performed to investigate functional implication of RARs. On an average, 23.1% of the total probes were altered per case. Mean numbers of altered probes are significantly higher in high-grade, bigger and microvascular invasion (MVI) positive tumors. In total, 32 RARs (14 gains and 18 losses) were defined and 4 most frequent RARs are gains in 1q21.1-q32.1 (64.5%), 1q32.1-q44 (59.2%), 8q11.21-q24.3 (48.7%) and a loss in 17p13.3-p12 (51.3%). Through focusing on RARs, we identified genes and functional pathways likely to be involved in hepatocarcinogenesis. Among genes in the recurrently gained regions on 1q, expression of KIF14 and TPM3 was significantly increased, suggesting their oncogenic potential in HCC. Some RARs showed the significant associations with the clinical features. Especially, the recurrent loss in 9p24.2-p21.1 and gain in 8q11.21-q24.3 are associated with the high tumor grade and MVI, respectively. Functional analysis showed that cytokine receptor binding and defense response to virus pathways are significantly enriched in high grade-related RARs. Taken together, our results and the strategy of analysis will help to elucidate pathogenesis of HCC and to develop biomarkers for predicting behaviors of HCC.

CD63 as a biomarker for predicting the clinical outcomes in adenocarcinoma of lung.

BACKGROUND: The prognosis of lung cancer is still poor, since there are few early detection tools available yet. So, it is important to identify more efficient and clinically applicable biomarkers associated with the prognosis in as earlier stages as possible. PATIENTS AND METHODS: In this study, we observed the expression of CD63 in 90 cases of non-small cell lung cancer (NSCLC) to explore the potential of this molecule as a prognostic biomarker for lung cancer subtypes using real-time quantitative RT-PCR and tissue microarray based immunohistochemistry. RESULTS: Majority of NSCLCs (75.8%) showed lower CD63 RNA level (less than half) than normal tissue. Notably, all SqCs showed low-expression except one case, while AdCs showed diverse range of expression. CD63 protein expression level was largely compatible with RNA level. Totally, 63.3% of NSCLC were CD63 protein expression negative. All SqCs were negative, while majority (70.2%) of adenocarcinomas (AdCs) were positive. CD63 protein negativity was significantly associated with SqCs type, larger tumor size, and advanced stage. In AdCs, CD63 negativity was associated with poor survival (p=0.008). This association was also significant in earlier stage (I and II) AdCs (p=0.041), but not in advanced stage AdCs. After being adjusted for age and sex by Cox regression and stratified by stages, CD63 negativity still showed borderline association with poor survival as an independent predictor (p=0.076, HR=2.3). CONCLUSIONS: Taken together, these results suggest that CD63 can be a biomarker for predicting the prognosis in earlier stage of lung AdCs. Our findings can be a clue to investigate the role of CD63 in tumorigenesis of AdCs of lung and other cancers.

Recurrent genomic alterations with impact on survival in colorectal cancer identified by genome-wide array comparative genomic hybridization.

BACKGROUND & AIMS: Although genetic aspects of tumorigenesis in colorectal cancer (CRC) have been well studied, reliable biomarkers predicting prognosis are scarce. We aimed to identify recurrently altered genomic regions (RAR) in CRC with high resolution, to investigate their implications on survival and to explore novel cancer-related genes in prognosis-associated RARs. METHODS: A 1-Mb resolution microarray-based comparative genomic hybridization (array CGH) was applied to 59 CRCs. RARs, defined as genomic alterations, detected in more than 10 cases were identified and analyzed for their association with survival. Expression levels of genes in prognosis-associated RARs were examined by real-time quantitative polymerase chain reaction. RESULTS: Twenty-seven RARs were identified. Eleven high-level amplifications and 2 homozygous deletions also were detected, but they were not as common as RARs. Multivariate analysis revealed RAR-L1 (loss on 1p36; hazard ratio = 8.15, P = .002) and RAR-L20 (loss on 21q22; hazard ratio = 3.53, P = .034) are independent indicators of poor prognosis. Expression of CAMTA1, located in RAR-L1, was reduced frequently in CRCs, and low CAMTA1 expression was associated significantly with poor prognosis, which indicates that CAMTA1 may play a role as a tumor suppressor in CRC. Five pairs of RARs were correlated significantly to each other and 3 pairs share genes involved in the same biological functions, suggesting possible collaborative roles in tumorigenesis. CONCLUSIONS: We identified recurrent genomic changes in 59 CRCs. RARs could be more important in sporadic tumors where the effect of genomic changes on tumorigenesis is relatively smaller than in familial cancer. Our results and analysis strategy will be helpful to elucidate pathogenesis of CRCs or to develop biomarkers for predicting prognosis.

p21 as a prognostic factor in non-small cell lung carcinomas.

Few studies have focused on the correlation between p21 expression and survival for patients with non-small cell lung carcinoma (NSCLC), and the results are not consistent. We investigated the expression of p21 in 90 cases of NSCLC to evaluate the correlation between the p21 expression level and the clinicopathologic characteristics with patient survival. p21 was expressed in the nuclei of all the NSCLCs. The percentage of immunoreactive cells varied from 1% to 70%. All the patients were subdivided into a high and a low p21 expression group on the basis of the median percentage (17.05). There was no significant correlation between the p21 expression level and age, gender, histologic type, histologic grade, or stage. Using uni- and multivariate analyses, survival was significantly associated with gender, stage, and the p21 expression level. The survival rate for the high p21 expression group was higher than that for the low p21 expression group in the entire patient group, and especially for stage II and III patients, males, adenocarcinomas, or p53-positive tumors. Our findings showed that high p21 expression was an independent prognostic factor for NSCLC. p21 may be useful for determining the candidates for adjuvant therapies and also for selecting the appropriate chemotherapeutic agents.

Genome-wide screening of genomic alterations and their clinicopathologic implications in non-small cell lung cancers.

PURPOSE: Although many genomic alterations have been observed in lung cancer, their clinicopathologic significance has not been thoroughly investigated. This study screened the genomic aberrations across the whole genome of non-small cell lung cancer cells with high-resolution and investigated their clinicopathologic implications. EXPERIMENTAL DESIGN: One-megabase resolution array comparative genomic hybridization was applied to 29 squamous cell carcinomas and 21 adenocarcinomas of the lung. Tumor and normal tissues were microdissected and the extracted DNA was used directly for hybridization without genomic amplification. The recurrent genomic alterations were analyzed for their association with the clinicopathologic features of lung cancer. RESULTS: Overall, 36 amplicons, 3 homozygous deletions, and 17 minimally altered regions common to many lung cancers were identified. Among them, genomic changes on 13q21, 1p32, Xq, and Yp were found to be significantly associated with clinical features such as age, stage, and disease recurrence. Kaplan-Meier survival analysis revealed that genomic changes on 10p, 16q, 9p, 13q, 6p21, and 19q13 were associated with poor survival. Multivariate analysis showed that alterations on 6p21, 7p, 9q, and 9p remained as independent predictors of poor outcome. In addition, significant correlations were observed for three pairs of minimally altered regions (19q13 and 6p21, 19p13 and 19q13, and 8p12 and 8q11), which indicated their possible collaborative roles. CONCLUSIONS: These results show that our approach is robust for high-resolution mapping of genomic alterations. The novel genomic alterations identified in this study, along with their clinicopathologic implications, would be useful to elucidate the molecular mechanisms of lung cancer and to identify reliable biomarkers for clinical application.

Aspiration cytology of pulmonary small cell variant of poorly differentiated synovial sarcoma metastatic from the tongue: a case report.

BACKGROUND: Small cell variant ofpoorly differentiated synovial sarcoma (PDSS) is a great mimic of Ewing's sarcoma/primitive neuroectodermal tumor, with cytologic and immunohistochemical overlap. CASE: A 21-year-old male was admitted to our hospital because of a solitary pulmonary nodule that developed 22 months after resection of a tongue mass, small cell variant of PDSS. The nodule was biopsied via fluoroscopy-guided fine needle aspiration (FNA). At low power, the cytologic smears were highly cellular, consisting of a mixture of dispersed cells and loose or tight tissue fragments. The cells were characteristically uniform and monotonous, showing round to ovoid nuclei and scant cytoplasm. However, at high power, mild nuclear pleomorphism and frequent mitotic figures were noted. Blood vessels were often seen within the tumor cell aggregates. A diagnosis of metastatic sarcoma was rendered. Metastatectomy of the lung nodule was performed, and cytogenetic study showed t(X;18). CONCLUSION: A diagnosis of small cell variant of PDSS is difficult on routinely stained smears, but in the appropriate clinical setting, especially when a prior history of a primary tumor is available, a confident diagnosis can be established by FNA cytology. Immunohistochemistry and identification of SYT/SSX fusion transcript are useful for confirmation.

Aspiration cytology of mediastinal seminoma: report of a case with emphasis on the diagnostic role of aspiration cytology, cell block and immunocytochemistry.

BACKGROUND: Medigstinal seminoma ia an uncommon tumor that occurs primarily in young males. We present a case of mediastinal seminoma in an elderly male diagnosed on fine needle aspiration (FNA) tytology. CASE: A 62-year-old male was admitted to our hospital because of anterior chest pain for 2 weeks. Chest computed tomography revealed a huge, lobulated mass in the anterior mediastinum. Aspirate smears were highly cellular. The tumor cells appeared singly or in loose groups of a few cells in a markedly necrotic background without lymphocytic or tigroid characteristics. Well-preserved cells were relatively uniform, large and polygonal, with round or ovoid nuclei, 2 1 prominent nucleoli and a mild to moderate amount of clear, occasionally vacuolated cytoplasm. The chromatin wasfinely granular. Mitotic figures were frequently found. The cell block section showed solid nests of tumor cells with cytologic features similar to those in the smears, supported by loose, fibrous stroma infiltrated by some lymphocytes. Immunocytochemically the tumor showed diffuse reactivity for c-kit and appearedfocally positive for placentalike alkaline phosphatase and was uniformly negative for pancytokeratin, CAM 5.2 low-molecular-weight cytokeratin, CD5, CD30, alpha-fetoprotein and leukocyte common antigen. CONCLUSION: A confident diagnosis of mediastinal seminoma can be established by FNA cytology, cell block and immunocytochemistry.

Extensive and divergent chromosomal losses in squamous and spindle-cell components of esophageal sarcomatoid carcinoma.

Sarcomatoid carcinoma of the esophagus is an unusual type of squamous cell carcinoma (SCC) with a variable component of sarcomatoid spindle cells (SA). The loss of heterozygosity (LOH) involving multiple cancer-associated chromosomal arms has been reported to have a concerted, rather than an individual, effect on tumor progression. In order to delineate the role of LOH in the evolution of a biphasic tumor, the carcinoma in situ (CIS), invasive squamous cell carcinoma (ISCC), and SA components from a sarcomatoid carcinoma of the esophagus were compared for their clonality and extent of LOH. Forty microsatellite markers on the cancer-associated chromosomes, 3p, 4p, 5q, 8p, 9p, 13q, 17p, and 18q, were used for the polymerase chain reaction-based LOH analysis. All eight sarcomatoid carcinomas tested revealed extensive LOHs, involving an average of seven chromosomal arms. All CIS, ISCC, and SA components carried not only a high-level primary LOH (mean chromosomal involvement, 5.3) in common but also a low-level secondary LOH (mean chromosomal involvement, 1.8) in disparity. Interestingly, more secondary LOHs were always burdened in the CIS (four cases) rather than the matched ISCC. SA had a greater (four cases), equal (one case), or fewer (one case) number of secondary LOHs than ISCC. Given that excessive chromosomal losses may confer a disadvantage for tumor growth or a benefit for a metaplastic transformation, these results suggest that the multidirectional differentiation of a SCC precursor is stimulated by extensive and divergent LOHs acquired at the initial or early stages, and a precursor burdened with excessive LOH either remains in CIS or expands as a SA component.

Detection of germinal center B-cell lymphoma in archival specimens: critical evaluation of Bcl-6 protein expression in diffuse large B-cell lymphoma of the tonsil.

Expression of Bcl-6 and CD10, markers for the tumor of the germinal center (GC) B-cell derivation, has been studied in primary diffuse large B-cell lymphomas (DLBCLs) of the lymph node, gastrointestinal tract, and mediastinum. In these studies, the coexpression rate of CD10 and Bcl-6 was relatively constant at 30% approximately 40%, but the frequency of Bcl-6+ tumors varied from 55% to 100%, raising doubts about the usefulness of Bcl-6 expression in identifying the tumor of GC B-cell derivation. Because the expression of Bcl-6 in tumors of non-GC B-cell origin has recently been reported, we critically evaluated the expression of Bcl-6 and CD10 in primary DLBCLs of the tonsil, a relatively common tumor in Japan and Korea. The cases (n = 51) represented a consecutive series for any recent 2-year period at several teaching hospitals in Korea and Japan. Formalin-fixed, paraffin-embedded specimens were used for immunostaining. Staining for Bcl-6 and CD10 was positive in 44 (86%) and 22 cases (45%), respectively. However, among those positive for Bcl-6 (>10% Bcl-6+ tumor cells), 2 basic patterns were recognized: uniform and nonuniform. The uniform pattern was characterized by a dense population (>75%) and a consistent density in any given area, resembling the staining pattern observed in GC or follicular lymphoma (FL) (the "GC/FL" pattern). In contrast, the nonuniform pattern exhibited a varying density from area to area, as well as a less-dense population (<75%). The uniform pattern was observed in 26 cases (51%). All but 1 (95%) of the CD10+ tumors coexpressed Bcl-6, with most (82%) displaying the uniform pattern. We conclude that tumors showing a uniform pattern of Bcl-6 expression should be distinguished from those showing a nonuniform pattern, because the former most likely represent tumors of GC B-cell derivation and the latter most likely represent tumors of non-GC derivation. GC B-cell lymphoma thus defined accounted for 51% of tonsillar DLBCL, a proportion comparable to that of the nodal DLBCL. CD10 expression correlated with the "GC/FL" pattern, but appeared to be not essential for the identification of GC B-cell lymphoma. This study suggests that a significant proportion of tonsillar DLBCLs in Asia is of GC B-cell origin rather than of mucosa-associated lymphoid tissue origin. This finding may have significance for clinical management of these lymphomas.

Critical evaluation of Bcl-6 protein expression in diffuse large B-cell lymphoma of the stomach and small intestine.

UNLABELLED: Diffuse large B-cell lymphoma (DLBCL) of the gastrointestinal tract is heterogeneous, including mucosa-associated lymphoid tissue (MALT) origin and non-MALT, and they are indistinguishable. MALT lymphoma is a tumor of a post-germinal center (GC) memory B-cell origin, which is negative for Bcl-6 protein expression in low-grade but may become positive in high-grade tumors. Because Bcl-6 expression patterns in lymphoma of GC and non-GC B-cell origins have recently been characterized and CD10 is generally regarded as a specific marker for GC B cells, we critically evaluated gastric and small intestinal DLBCLs to see whether it is possible to identify tumor of GC B-cell origin by immunostaining in archival specimens. High-grade MALT lymphoma (H-ML) of the stomach (n = 20) was defined by the presence of a concomitant lymphoepithelial lesion and/or follicular colonization; and DLBCLs de novo, both gastric (n = 31) and intestinal (n = 21), were defined by the absence of the above features. Immunostaining for Bcl-6 and CD10 was done using formalin-fixed, paraffin-embedded sections and was examined independently by three pathologists. Staining for Bcl-6 was positive (>10% of tumor cells) in 55 of 72 cases. However, two distinct patterns were recognized among those positive: diffusely dense (>75%) and sporadic (<75%). The former was further characterized by a consistency of Bcl-6+ tumor cell density at any given area, resembling the staining pattern of the GC or follicular lymphoma (FL) (GC/FL pattern), whereas the latter was, besides less dense population, by variable density from area to area. The GC/FL pattern was observed in 36% and 38% of gastric and intestinal DLBCLs de novo, respectively, but in none of the gastric H-ML. CD10 was positive in 12 of 71 cases (17%), all coexpressing Bcl-6. CD10+ tumors were more frequent in the intestinal (33%) than in gastric DLBCLs ( approximately 15%). Significantly, CD10 expression was observed in three gastric H-MLs, including one that displayed a distinct lymphoepithelial lesion. IN CONCLUSION: 1). tumors showing a diffusely dense pattern of Bcl-6 expression should be distinguished from those showing a sporadic pattern; for the former most likely represents the tumor of GC B-cell derivation, and the latter non-GC, including MALT lymphoma; 2). tumor of GC B-cell origin thus defined accounted for about one third of gastric as well as intestinal DLBCLs de novo but none of the gastric H-ML; and 3). CD10 expression can be seen in MALT lymphomas and should not be used as the marker for GC B cells.

Schwannomas of the gastrointestinal tract: clinicopathological features of 12 cases including a case of esophageal tumor compared with those of gastrointestinal stromal tumors and leiomyomas of the gastrointestinal tract.

We analyzed the clinicopathological features of 12 gastrointestinal (GI) schwannomas and compared them with those of 37 GI stromal tumors (GISTs) and 15 leiomyomas. Grossly, the schwannomas showed rubbery to firm, yellow-white to tan, glistening, and often trabeculated cut surfaces, resembling soft tissue schwannomas. The GISTs were firm to soft or fish-flesh tan, gray-pink, or variegated tumors with a degenerative change, and the leimyomas resembled typical uterine leiomyomas. Histologically, GI schwannomas were moderately cellular tumors with focal significant nuclear pleomorphism and rare mitotic figures. A characteristic peripheral lymphoid cuff was observed in all cases, but was indistinct in two cases. The GISTs were highly cellular spindle cell, epithelioid or, occasionally, pleomorphic tumors with basophilic appearance. Leiomyomas were paucicellular tumors with eosinophilic appearance. Immunohistochemically, schwannomas were S-100 protein- and glial fibrillary acidic protein (GFAP)-positive, but were negative for c-kit, CD34, and smooth muscle actin (SMA). GISTs were all c-kit- and/or CD34-positive, but GFAP-negative. Leiomyomas were SMA-positive and were negative for c-kit, CD34, S-100 protein, and GFAP. The mean Ki-67 index of schwannoma was 0.7, and those of GIST and leiomyoma were 5.9 and 0.3, respectively. The patients with schwannomas and leiomyomas had a favorable outcome, whereas 12 patients with GISTs showed progression and died of disease. The separation of GISTs from schwannomas is clinically important because the former group has a high risk of malignant behavior. GI schwannomas differed from the conventional soft tissue schwannomas in that they had peripheral lymphoid cuffs, lacked fibrous capsule and vascular hyalinization, and rarely showed degenerative changes. GI schwannomas, however, resembled soft tissue schwannomas in many aspects, and the clinical, gross, histological, and immunohistochemical features were different from those of GISTs and leiomyomas.

Genetic classification of colorectal cancer based on chromosomal loss and microsatellite instability predicts survival.

PURPOSE: Colorectal cancers harbor one of two distinct alterations, unilateral chromosomal loss as evidenced by a loss of heterozygosity (LOH) and microsatellite instability (MSI), as represented by the widespread insertion or deletion of simple repeat nucleotides. We investigated the relationships between the clinicopathological features and microsatellite alterations (LOH and MSI) of 168 colorectal cancers. EXPERIMENTAL DESIGN: The concerted and individual effects of various chromosomal losses on survival were comparatively analyzed using a reference panel of 40 microsatellite markers in eight cancer-related chromosomes, 3p, 4p, 5q, 8p, 9p, 13q, 17p, and 18q. RESULTS: Of the 168 colorectal cancers tested, 29 (17%) with high-frequency MSI were associated with good survival (P < 0.05). The extent of LOH detected in 139 (83%) cases without MSI was classified as low level involving three or fewer arms (35%), moderate level involving four arms (22%), or high level involving five or more arms (43%). High-level loss correlated with earlier onset, lymphatic invasion, and rectal location, whereas low-level loss was more common in proximal colon and stages I and II (P < 0.05). The survival curve and multivariate analysis identified high- and low-level chromosomal loss as the most significant predictor of poor and good survival, respectively (log-rank test, P < 0.0001), in patients with stage II (hazard ratio, 6.27; 95% confidence interval, 1.99-19.7; P = 0.0017) and those with stage III (hazard ratio, 10.89; 95% confidence interval, 2.54-46.77; P = 0.0013). Moderate chromosomal loss showed dual prognostic values associated with favorable stage II and unfavorable stage III. Single chromosomal losses tended to play a role as a part of the concerted chromosomal function. CONCLUSION: The classification of colorectal cancer based on chromosomal loss and MSI provides a prognostic index that reflects tumor pathobiology.

Fine needle aspiration cytology (FNAC) of gastrointestinal stromal tumor: an emphasis on diagnostic role of FNAC, cell block, and immunohistochemistry.

Recently the origin of gastrointestinal stromal tumors (GISTs) is thought be the interstitial cells of Cajal or primitive stem cells. This study was performed to evaluate the roles of fine needle aspiration cytology (FNAC), cell block preparation, and immunohistochemistry in the diagnosis of GISTs. Nine cases of GIST in which FNAC was performed were included in this study. Cytologically, the tumor cells characteristically occurred in closely packed cohesive tissue fragments with high cellular density often in bloody background. The tumor cells often formed fascicles with parallel, side-by-side arrangements of the nuclei. Histologically, GISTs were highly cellular spindle or epithelioid tumor with basophilic appearance. Immunohistochemically, GISTs were c-kit positive in all of nine cases, CD34 positive in seven, focally SMA positive in two, and S-100 and GFAP negative in all. Both histologic and cell block sections showed the same histologic and immunohistochemical features. Cytomorphologically GISTs show a broad morphologic spectrum but rarely a significant nuclear pleomorphism and the assessment of malignant potential is difficult based on cytology alone. However, in the appropriate clinical and radiologic setting, a confident diagnosis of primary or metastatic GIST can be established by FNAC, cell block, and immunohistochemistry.