Leukocyte-common antigen and vimentin are reliable adjuncts in the diagnosis of non-Hodgkin's lymphoma in fine needle aspirates

Alcohol-fixed fine needle aspirates of 82 non-Hodgkin's malignant lymphomas (NHLs) were tested for the presence of vimentin and leukocyte-common antigen (LCA) by means of monoclonal antibodies (MAbs) and indirect immunofluorescence. All NHLs stained positively for vimentin; the staining was strong in all except three cases. Of the 69 NHLs tested for LCA, 1 (a large cell T-cell lymphoma) was negative while the staining was weak in 6. Thus, vimentin and LCA MAbs are sensitive, specific and reliable complementary diagnostic adjuncts that are useful in the definitive diagnosis of NHLs in alcohol-fixed fine needle aspirates. Their presence in the aspirate confirmed a cytologic diagnosis of NHL in 47 cases, helped to diagnose NHL in 31 cases in which a cytologic differential diagnosis with small cell anaplastic carcinoma could not be made with confidence and helped to change the initial cytologic diagnosis of anaplastic carcinoma to NHL in 4 cases.     

Fine needle aspiration of metastatic and hematologic malignancies clinically mimicking pancreatic carcinoma.

The fine needle aspiration (FNA) cytology findings in 19 cases of hematopoietic and metastatic neoplasms that radiographically mimicked primary pancreatic carcinoma are reported. These cases represented 11% of 176 malignant diagnoses in a series of 304 pancreatic FNAs. The cytologic diagnoses included 7 non-Hodgkin's lymphomas, 2 Hodgkin's lymphomas, 6 small cell carcinomas (4 lung, 1 gallbladder, 1 skin), 3 squamous cell carcinomas (2 cervix, 1 esophagus) and 1 hepatocellular carcinoma. In six cases the pancreatic lesion was the initial presentation of malignant disease. These included five lymphomas, which probably involved peripancreatic lymph nodes, and a metastatic small cell carcinoma of pulmonary origin. Recognition of unusual morphologic features of pancreatic carcinoma raised the possibility of extrapancreatic malignancies. Electron microscopy and immunocytochemistry performed on FNA specimens were helpful in selected cases. The FNA diagnosis of hematopoietic and metastatic neoplasms that clinically mimic pancreatic carcinoma prompts appropriate clinical studies and treatment and eliminates the need for open pancreatic biopsy and/or resection.     

Fine Needle Aspiration Cytology of High Grade T-Cell Lymphomas In Human T-Lymphotropic Virus Type 1 Carriers

We studied the fine needle aspiration (FNA) cytology of high grade peripheral T-cell lymphomas from eight human T-lymphotropic virus-1 (HTLV-1) positive patients. FNA smears from seven lymphomas showed a distinctive cytologic pattern with a dominance of rounded cells with irregular nuclei and a moderately basophilic cytoplasm. Irregular cells with a pale abundant cytoplasm were present in varying amounts. Some smears contained a few giant cells with cerebriform nuclei. In addition, plasma cells and eosinophils were found. Epithelioid cells were an inconstant finding. On histology these seven lymphomas were assigned to the pleomorphic medium-large cell subtype and all but one were of T-helper phenotype with rearrangements of the T-cell receptor. FNA smears from a lymph node in a patient with a previous histological diagnosis of lymphomatoid papulosis of the gingiva showed a monotonous pattern of large immunoblastic cells with some binucleated variants consistent with a diagnosis of high grade immunoblastic lymphoma, which was confirmed histologically. Our results show that peripheral T-cell lymphomas from HTLV-1 positive patients have cytological patterns which are distinctive enough to allow a conclusive diagnosis of high grade T-cell lymphoma. However, we do not think that the cytology of HTLV-1 positive lymphomas can be differentiated from that of virus-unrelated high grade T-cell lymphomas.     

Fine needle aspiration cytology of primary bone lesions

Fine needle aspiration (FNA) cytologic findings were compared with the results of conventional histology in a series of primary bone lesions to determine the diagnostic accuracy of FNA cytology. The series included 12 osteogenic sarcomas, 4 Ewing's sarcomas, 3 chordomas, 3 myelomas, 2 chondrosarcomas, 2 undifferentiated sarcomas and 1 case each of normal bone and marrow elements, lymphoma and giant-cell tumor. All aspirates yielded adequate material for smear diagnosis, and all 29 cases were correctly identified as benign or malignant by cytology. In 19 cases (66%), specific cytologic diagnoses were rendered and histologically confirmed. This series is compared with other published series of bone aspirations in terms of technique, accuracy and ability to obtain diagnostic material. The importance of technique, radiographic investigations and experience in performing the aspirations in achieving a high diagnostic yield is emphasized.     

Fine needle aspiration cytology of rare malignant tumors of the breast.

This report describes the fine needle aspiration (FNA) cytologic findings in 17 rare malignant breast tumors. The series consisted of invasive cribriform carcinoma, papillary carcinoma, apocrine carcinoma, carcinoma with pseudosarcomatous metaplasia, carcinosarcoma, fibrosarcoma, malignant phyllodes tumors, primary malignant lymphomas, plasmocytoma, metastatic melanoma and metastatic renal clear cell carcinoma. Besides cytomorphology, the results of immunostaining in eight cases are presented, as is a review of the literature. It is important for rare primary malignancies, as well as for metastatic tumors, to be diagnosed, or at least have the diagnosis suggested, preoperatively by FNA and immunocytochemistry, permitting better therapy planning.     

Cytomorphologic characteristics of non-Hodgkin's lymphoma

The cytologic samples of 84 non-Hodgkin's lymphomas, classified according to the Rappaport system, were reviewed, with particular attention to the cell pattern, the size of the cells and other morphologic characteristics. The analysis revealed that: (1) the subgroups of malignant lymphoma in the Rappaport classification display a heterogeneous cytologic picture; (2) cytology cannot make the differentiation between nodular and diffuse non-Hodgkin's malignant lymphomas; and (3) reliable cytologic classification is possible only in certain cases of well-differentiated lymphocytic and diffuse histiocytic lymphomas. Well-differentiated lymphocytic lymphoma is characterized by a uniform cell picture consisting of mature lymphocytes, prolymphocytes or centrocytes up to 12 micron in size, by the presence of paraimmunoblasts and by the absence of reticulum cells. The diffuse histiocytic lymphoma contains over 48% centroblasts or over 8% immunoblasts or multinucleated giant blast cells.     

Fine needle aspiration cytology of lactating adenoma of the breast. A comparative light microscopic and morphometric study

Six cases of lactating adenoma of the female breast diagnosed by fine needle aspiration (FNA) were reviewed. The FNA cytologic diagnostic features included a usually moderately cellular aspirate with an abundant foamy background material, intact epithelial lobules or acini and small groups and solitary epithelial cells that contained uniform nuclei, fine chromatin and prominent nucleoli. When present, the cytoplasm was finely vacuolated or wispy; many nuclei appeared stripped of their cytoplasm. These features were compared light microscopically with the cytopathologic features of six cases of invasive well-differentiated ductal adenocarcinoma, seven cases of invasive lobular carcinoma, one case of granulocytic sarcoma and one case of primary histiocytic lymphoma of the breast. In addition, cytomorphometric analysis demonstrated no statistically significant differences in the nuclear areas of lactating adenoma as compared with those of well-differentiated ductal carcinoma and lobular carcinoma.     

Morphologic and immunocytochemical evaluation of 220 fine needle aspirates of malignant lymphoma and lymphoid hyperplasia

A total of 220 fine needle aspiration (FNA) specimens from 212 patients with clinically suspected or previously histologically confirmed lymphoma were evaluated by cytology in conjunction with immunophenotyping analysis of the aspirate; the results were compared with the histologic diagnosis made on previous or current accessions of lymph node or extranodal tissue. Smears of the aspirates were stained with the Diff-Quik and Papanicolaou stains while immunoperoxidase staining using antibodies against kappa and lambda immunoglobulin light chains and Leu-4 was routinely performed on Cytospin preparations. Where indicated, additional marker studies (including T-200, Leu-1, Leu-2a, Leu-3a + 3b, Leu-M1, B1, Leu-12, IgM, CALLA and TdT) were performed. For the non-Hodgkin's lymphomas, specimens were classified by the cytologic characteristics of the neoplastic cells according to the International Working Formulation scheme. The combination of cytologic smears and immunoperoxidase studies resulted in a diagnosis of lymphoma in 173 cases (79%). The remaining aspirates were interpreted as suspicious for lymphoma (7%), benign (10%) or inadequate for diagnosis (4%). Of the 15 suspicious aspirates, 5 proved to be Hodgkin's disease and 2 to be T-cell lymphoma by subsequent biopsy. The cause of failure in the nine inadequate aspirates were necrosis (3 cases), sclerosis (2 cases) and faulty technique (4 cases). In the cases that had concurrent tissue biopsies, no false-positive diagnoses were rendered. These results indicate that FNA used in association with immunocytochemistry is a reliable tool for establishing the diagnosis and classification of the majority of cases of lymphoma. Optimal immunoglobulin light-chain ratios for defining monoclonality in FNA specimens of B-cell lymphomas are proposed.     

Multilobated large B-cell lymphoma diagnosed cytologically. A case report.

BACKGROUND: Fine needle aspiration (FNA) biopsy can be used to reliably classify most conditions involving lymph nodes or, at least, significantly reduce the differential diagnosis. CASE: A 70-year-old male presented with an ulcerated mass arising from the left tonsillar fossa and involving the anterior and posterior pillars. A biopsy of the tonsillar mass performed at an outside hospital was interpreted as a large cell undifferentiated carcinoma. Subsequently the patient developed systemic lymphadenopathy. A bone scan showed intense uptake within the medial tibial plateau of the left knee. FNA biopsy of the right axillary mass was interpreted at University of Cincinnati Medical College as a large cell lymphoma, multilobated type. Histologic and immunohistochemical studies of the lymph node confirmed the presence of multilobated B-cell lymphoma. Lymphoma chemotherapy was initially successful but was discontinued due to toxicity. The patient died two months after the initial cytologic diagnosis of lymphoma. CONCLUSION: Multilobated lymphomas are an unusual variant of non-Hodgkin's lymphomas (mostly B-cell type). Cytology and immunocytochemistry are useful diagnostic procedures that can help to diagnose this relatively uncommon type of lymphoma and significantly reduce the possibility of misdiagnosis.     

Fine needle aspiration (FNA) biopsy of orbital masses: a critical review of 51 cases

Fine needle aspiration (FNA) biopsy of orbital masses: a critical review of 51 cases
FNA biopsy of 51 orbital masses is critically reviewed. Aspiration was performed with a 23 G needle inserted by an ophthalmologist; the smears were prepared by a cytologist. Forty-two cases (83%) were correctly diagnosed as benign or malignant either with (68%) or without (15%) correct specification of the histology. There were two false-negative and seven inadequate cases. Immunocytochemical stains were performed in five cases using the following antibodies: L26 (Pan B), UCHL1 (Pan T), and immunoglobulin light chains (three cases) in order to distinguish inflammatory pseudotumours from low-grade non-Hodgkin's lymphomas. In two cases we used CAM 5.2 (a monoclonal cytokeratin cocktail) and vimentin to ascertain the epithelial origin of two metastatic tumours. In five other cases cytospins were not adequately cellular for immunocytochemistry. Insufficient material and one false-negative sample were obtained from very fibrotic lesions or from posteriorly located lesions. The results are discussed and compared with other series reported in the literature. Orbital FNA biopsy may be considered a useful tool in the diagnostic approach to orbital masses in which the relatively high number of inadequate aspirations is offset by a low cost-benefit ratio.     

Fine needle aspiration cytology of neoplasms metastatic to the breast

The fine needle aspiration (FNA) cytologic findings in 18 cases of metastatic neoplasms of the breast are reported. The cases were encountered in a combined series of 2,529 FNA breast biopsies, of which 666 were malignant; the metastatic neoplasms of the breast thus constituted 2.7% of all the malignant breast tumors. The series consists of 15 women and 3 men, with a mean age of 48 years (range of 11 to 73 years). Sixteen biopsies confirmed metastatic malignancy in patients with known extramammary primaries; the prebiopsy clinical diagnoses in six of the patients were benign breast lesions. In eight patients, the clinical differential diagnosis was either a benign or malignant primary breast lesion versus a metastatic malignancy. In two additional patients, the FNA biopsy identified metastatic neoplasms from unsuspected extramammary primaries. The metastatic neoplasms included three small-cell carcinomas of the lung, one squamous-cell carcinoma of the lung, two malignant melanomas, three ovarian malignancies, including a dysgerminoma, and one each of carcinoma of the fallopian tube, endometrial carcinoma, transitional-cell carcinoma of the urinary bladder, prostatic carcinoma, acute granulocytic leukemia, lymphoma, mycosis fungoides, hepatoma and neuroblastoma of the retroperitoneum. Recognition of unusual cytologic patterns raised the suspicion of, or confirmed the diagnosis of, malignancy in all cases, with no false-negative diagnoses. None of the cases were cytologically interpreted as a primary breast malignancy. Ancillary studies performed on the FNA material, including immunocytochemistry, contributed to a definitive diagnosis in three cases. FNA diagnosis of metastatic malignancy of the breast is essential in order to avoid unnecessary mastectomy and to ensure appropriate chemotherapy and/or irradiation treatment.     

Fine needle aspiration cytology and immunocytochemistry in the diagnosis of lymphoid lesions of the thyroid gland

Immunocytochemical analysis was used in conjunction with cytomorphology to evaluate fine needle aspirates from 18 patients with nodular lymphoid infiltrates of the thyroid. The smears from 13 patients had a cytomorphology that was diagnostic of chronic lymphocytic thyroiditis; immunocytochemistry showed the lymphoid population to be composed of T cells and polyclonal B cells. Three patients had high-grade malignant lymphomas by cytomorphology; immunologic evaluation showed the B-cell phenotype of the lymphoma cells and monoclonal light chain expression. Cytomorphology could not differentiate between an inflammatory and a neoplastic lymphoid infiltrate in two cases. Immunocytochemical analysis showed that the cells of B-cell phenotype were monoclonal (neoplastic) in one case and polyclonal (inflammatory) in one case.     

Posters. P1 A 2‐year audit of thyroid fine needle aspiration cytology

Introduction Fine needle aspiration (FNA) cytology of the thyroid is a well‐established test in the clinical work‐up of patients with solitary nodules of the thyroid. Thyroid FNA does however have limitations and audit of diagnostic performance is important. Methods The histopathology archives of the Royal Victoria Hospital were searched for all thyroid resections and the histopathological diagnosis was correlated with the pre‐operative cytological diagnosis, where available. Special emphasis was placed on the accuracy of tumour diagnosis. Results A total of 173 cases were identified during the 2‐year period, of these 93 had available pre‐operative FNA. A total of 57 tumours were identified. A small number (six of 57) of significant discrepancies were identified. These included a malignant lymphoma diagnosed as Hashimoto's thyroiditis, a metastasis which the FNA had suggested was a medullary carcinoma and an insular carcinoma diagnosed as medullary carcinoma on FNA. False positives included a colloid cyst diagnosed as suspicious of malignancy and a cytological diagnosis of papillary carcinoma not confirmed on histology. Discussion At present, the majority of thyroid FNAs in our clinics are performed by surgeons and material is not routinely available for immunocytochemistry. In spite of these limitations, there were few major discrepancies. These might be reduced if pathologist aspirators were able to perform FNAs and collect material for further studies, where necessary. This would allow identification of medullary carcinomas and malignant lymphomas. Conclusion FNA of thyroid lesions is a useful investigation in our clinical setting, however, some areas of potential for improvement have been identified.     

Fine needle aspiration biopsy in the evaluation of lymphoreticular tumors of the thorax

The role of fine needle aspiration (FNA) biopsy in the evaluation of lymphoreticular disorders involving the lung and mediastinum was evaluated in a study of 16 cases from the authors' institutions. The cytologic material from these cases was reviewed, and the original cytologic interpretations were compared to the tissue diagnoses, with the overall accuracy of the cytologic interpretation evaluated. There were no false-positive diagnoses of malignancy in this series. A definite diagnosis of malignant lymphoma was most readily made in those cases in which the lymphoma was of the large-cell type. Small-cell and mixed large-cell and small-cell lymphoid proliferations were less able to be definitively interpreted, with pseudolymphoma presenting particular difficulty. The results support the conclusion that FNA biopsy can be useful in evaluating these lesions but also emphasize the fact that accurate diagnosis requires correlation of cytologic, clinical and laboratory data.     

Primary multilobated T-cell lymphoma of the breast diagnosed by fine needle aspiration cytology and immunocytochemistry

The fine needle aspiration (FNA) cytologic, immunocytochemical and ultrastructural findings of a primary multilobated T-cell lymphoma arising in the breast of a 61-year-old woman are described. Large pleomorphic multilobated malignant cells were primarily identified as lymphomatous in origin and phenotypically as T-cells by a selected panel of monoclonal antibodies applied to the original smears obtained by FNA biopsy. This appears to be the second report of a multilobated lymphoma arising in the breast and the first with a T-cell phenotype in this anatomic site.     

Posters

Introduction  Fine needle aspiration (FNA) cytology of the thyroid is a well-established test in the clinical work-up of patients with solitary nodules of the thyroid. Thyroid FNA does however have limitations and audit of diagnostic performance is important.
Methods  The histopathology archives of the Royal Victoria Hospital were searched for all thyroid resections and the histopathological diagnosis was correlated with the pre-operative cytological diagnosis, where available. Special emphasis was placed on the accuracy of tumour diagnosis.
Results  A total of 173 cases were identified during the 2-year period, of these 93 had available pre-operative FNA. A total of 57 tumours were identified. A small number (six of 57) of significant discrepancies were identified. These included a malignant lymphoma diagnosed as Hashimoto's thyroiditis, a metastasis which the FNA had suggested was a medullary carcinoma and an insular carcinoma diagnosed as medullary carcinoma on FNA. False positives included a colloid cyst diagnosed as suspicious of malignancy and a cytological diagnosis of papillary carcinoma not confirmed on histology.
Discussion  At present, the majority of thyroid FNAs in our clinics are performed by surgeons and material is not routinely available for immunocytochemistry. In spite of these limitations, there were few major discrepancies. These might be reduced if pathologist aspirators were able to perform FNAs and collect material for further studies, where necessary. This would allow identification of medullary carcinomas and malignant lymphomas.
Conclusion  FNA of thyroid lesions is a useful investigation in our clinical setting, however, some areas of potential for improvement have been identified.     

Diagnosis of skeletal lymphoma and myeloma by radiology and fine needle aspiration cytology

Diagnosis of skeletal lymphoma and myeloma by radiology and fine needle aspiration cytology From 1986 to 1998, all patients referred to Karolinska Hospital because of a skeletal destruction of unknown origin routinely underwent radiographic examination and fine needle aspiration cytology (FNAC). Among these, there were 83 patients with solitary lesions of the bone diagnosed and treated for myeloma (plasmacytoma) or non-Hodgkin's lymphoma. Review of the series showed that myeloma could not be distinguished radiographically from lymphoma. Nor could low and high grade lymphoma lesions be discriminated by radiographic appearance. The diagnostic utility of plain radiography in the two conditions seems to be confined to the mere detection of a destructive bone lesion and visual guidance for FNAC. The latter aspect, however, is crucial for the application of FNAC to bone lesions. Review of the cytologic specimens obtained by FNAC showed that they allowed a conclusive diagnosis in all 40 myeloma cases and in 41 of 43 lymphoma cases. In 32 of the 40 myeloma cases, the FNAC material could be used for immunocytochemistry, which disclosed kappa or lambda light chain restriction, corroborating the cytomorphological diagnosis. Thirty-eight lymphomas were characterized immunologically and in 35, a light chain restriction could be demonstrated. Our results show that the use of FNAC in the diagnosis of primary myeloma and lymphoma of bone obviates the need for other diagnostic modalities, including open biopsy. A combined approach based on radiology and FNAC, performed as an out-patient procedure, offers rapid and accurate diagnosis of myeloma and lymphoma among patients with radiographically unclassified destructive bone lesions.     

Cytologic features of pheochromocytoma and retroperitoneal paraganglioma: a morphologic and immunohistochemical study of 13 cases

OBJECTIVE: To review the cytologic features and potential pitfalls of pheochromocytoma and retroperitoneal paraganglioma and to evaluate complications of the aspiration procedure and the diagnostic utility of immunocytochemistry. STUDY DESIGN: We reviewed 15 cytologic specimens from 12 patients with 13 tumors (1 bilateral case). Ten were adrenal (pheochromocytomas) and 3 extraadrenal paragangliomas. Eleven specimens were from fine needle aspiration (FNA) procedures that were performed in collaboration with radiologists using 23-25-gauge needles. In 3 patients the cytologic material was obtained during intraoperative diagnosis. Immunocytochemistry was performed on alcohol-fixed smears. RESULTS: Two aspirates were hypocellular, while the remainder were cellular. Cells were distributed singly or formed discohesive groups. When present, cytoplasm was abundant and ill defined. Most cells had an eccentric nucleus and plasmacytoid morphology. Nuclear pleomorphism, binucleation and multinucletaion, naked nuclei and intranuclear preudoinclusions were common findings. In 2 cases a lipid background was seen focally. Evident cytoplasmic immunoexpression of synaptophysin or chromogranin was detected in the 10 cases analyzed. One patient developed a hypertensive episode during the FNA procedure. It was controlled medically without complications. CONCLUSION: When adequate cytologic material is present, the recognition of pheochromocytoma and extraadrenal paraganglioma is possible. Together with morphology, immunocytochemical studies allow a specific preoperative diagnosis. Scarce material can be a source of diagnostic errors. FNA of pheochromocytomas is not necessarily contraindicated. When analytic data are not diagnostic, FNA may follow. Aspiration must be performed in an area equipped with the therapeutic tools necessary to control a pheochromocytoma crisis.     

Diagnosis of deep‐seated lymphomas by endoscopic ultrasound‐guided fine needle aspiration combined with flow cytometry

A. Stacchini, P. Carucci, D. Pacchioni, G. Accinelli, A. Demurtas, S. Aliberti, M. Bosco, M. Bruno, A. Balbo Mussetto, M. Rizzetto, G. Bussolati and C. De Angelis
Diagnosis of deep‐seated lymphomas by endoscopic ultrasound‐guided fine needle aspiration combined with flow cytometry Objective: Although endoscopic ultrasound combined with fine needle aspiration (EUS‐FNA) is rapidly becoming the preferred diagnostic approach for the sampling and diagnosis of gastrointestinal and mediastinal malignancies, there are limited data as to its use in the diagnosis of lymphoproliferative disorders. Therefore, we carried out a retrospective evaluation of the performance of EUS‐guided FNA combined with flow cytometry (FC) as a tool to improve overall sensitivity and specificity in the diagnosis of lymphoma. Methods: Of 1560 patients having EUS‐guided FNA during the period of the study, a total of 56 patients were evaluated by cytology with FC after EUS‐FNA. There was adequate material to perform FC analysis for all but one case. Results: EUS‐FNA‐FC gave a diagnosis of lymphoma in 11 cases and of reactive lymphadenopathy in 20. A specific histological type was defined by FC alone in eight cases. The remaining cases were diagnosed later by cytology and cell block sections: 13 carcinomas, nine granulomatous lymphadenopathies and one mediastinal extramedullary haematopoiesis. One case was considered only suspicious for lymphoma on cytology and FC but was not confirmed on molecular analysis and one had insufficient material for FC. Conclusions: Our results show that a combination of EUS‐FNA‐FC is a feasible and highly accurate method, which may be used for the diagnosis and subtyping of deep‐seated lymphoma, providing a significant improvement to cytomorphology alone both for diagnosis and treatment planning, as long as immunocytochemistry is available for non‐lymphoma cases.     

Preoperative cytologic diagnosis of primary gastrointestinal malignant lymphoma

This report is based on the review and study of primary gastrointestinal malignant lymphomas as seen in cytologic brushing and washing specimens. During a period of 12 years (1970 to 1981), a total of 2,675 patients with malignant lymphoma involving the gastrointestinal tract were seen at Memorial Sloan-Kettering Cancer Center. Of these patients, 73 were diagnosed as having primary malignant lymphoma of the gastrointestinal tract. A total of 49 preoperative cytologic specimens obtained from 29 patients with histologically confirmed primary gastrointestinal malignant lymphoma were examined and are the basis for this study. Twenty-four patients had gastric primaries; three tumors were in the colon and two were small intestinal lymphomas. Thirty-three cytologic specimens taken from 25 patients were considered diagnostic for malignant lymphoma. A positive cytologic brushing was the only diagnostic preoperative specimen for 9 of the 29 patients. Combined cytologic and biopsy specimens provided a diagnosis of malignant lymphoma for 16 patients. Cytologic washings did not add to the diagnostic accuracy. The 29 cases of malignant lymphoma reviewed here were histologically subclassified as 23 large-cell, poorly differentiated and six small-cell, well-differentiated lesions. The cytomorphologic features of malignant lymphoma as observed in gastrointestinal specimens are outlined, and differential diagnoses are discussed. Clinicopathologic implications of the cytologic findings are considered.