CD10, BCL6, and MUM1 expression in diffuse large B-cell lymphoma on FNA samples.

BACKGROUND: Gene expression profiling has divided diffuse large B-cell lymphoma (DLBCL) into 2 main subgroups: germinal center B (GCB) and non-GCB type. This classification is reproducible by immunohistochemistry using specific antibodies such as CD10, B-cell lymphoma 6 (BCL6), and multiple myeloma oncogene 1 (MUM1). Fine-needle aspiration (FNA) plays an important role in the diagnosis of non-Hodgkin lymphoma, and in some cases FNA may be the only available pathological specimen. The objectives of the current study were to evaluate CD10, BCL6, and MUM1 immunostaining on FNA samples by testing the CD10, BCL6, and MUM1 algorithm on both FNA cell blocks (CB) and conventional smears (CS), evaluating differences in CB and CS immunocytochemical (ICC) performance, and comparing results with histological data. METHODS: Thirty-eight consecutive DLBCL cases diagnosed by FNA were studied. Additional passes were used to prepare CB in 22 cases and CS in 16 cases; the corresponding sections and smears were immunostained using CD10, BCL6, and MUM1 in all cases. The data obtained were compared with histological immunostaining in 24 cases. RESULTS: ICC was successful in 33 cases (18 CB and 15 CS) and not evaluable in 5 cases (4 CB and 1 CS). The CD10-BCL6-MUM1 algorithm subclassified DLBCL as GCB (9 cases) and non-GCB (24 cases). ICC data were confirmed on histologic staining in 24 cases. CONCLUSIONS: CD10, BCL6, and MUM1 ICC staining can be performed on FNA samples. The results herein prove it is reliable both on CB and CS, and is equally effective and comparable to immunohistochemistry data.

Benign chondroblastoma on fine-needle aspiration smears: A seven-case experience and review of the literature.

We report seven cases of chondroblastoma (CB) of bone, diagnosed by Fine-Needle Aspiration Cytology (FNAC), and confirmed by histomorphological examination. The concurrence of some cytomorphologic findings - mononucleated cells, multinucleated cells, and intercellular chondroid substance - unequivocally suggested the cytological diagnosis of CB. We also reviewed the literature on this topic in order to discuss morphological criteria and the importance of needle size. The differential diagnosis between CB, Giant Cell Tumor of Bone, and Eosinophilic Granuloma is further discussed.

Multidisciplinary diagnostic approach combining fine needle aspiration, core needle biopsy and imaging features of a presacral myelolipoma in a patient with concurrent breast cancer.

Myelolipomas are uncommon benign tumors composed of mature adipose tissue mixed with hematopoietic elements; these tumors can occur in both the adrenal glands and extra-adrenal locations, the presacral region being the most frequent extra-adrenal site. We present a case of presacral myelolipoma diagnosed by fine needle aspiration (FNA) and core needle biopsy (CNB) in a 55-year-old woman with concurrent invasive ductal breast cancer. TC and RM imaging were consistent with the diagnosis of presacral myelolipoma. The lesion was discovered incidentally during the staging procedure for breast malignancy. The purpose of our work is to describe the FNA and CNB finding in combination with the imaging features of this uncommon lesion.

Lymph node fine needle cytology in the staging and follow-up of cutaneous lymphomas.

BACKGROUND: Lymph nodal involvement is an important clinical-pathological sign in primary cutaneous lymphoma (PCL), as it marks the transformation/evolution of the disease from localized to systemic; therefore the surveillance of lymph nodes is important in the staging and follow up of PCL. Fine needle cytology (FNC) is widely used in the diagnosis of lymphadenopathies but has rarely been reported in PCL staging and follow-up. In this study an experience on reactive and neoplastic lymphadenopathies arisen in PCL and investigated by FNC, combined to ancillary techniques, is reported. METHODS: Twenty-one lymph node FNC from as many PCL patients were retrieved; 17 patients had mycosis fungoides (MF) and 4 a primary cutaneous B-cell lymphoma (PBL). In all cases, rapid on site evaluation (ROSE) was performed and additional passes were used to perform flow cytometry (FC), immunocytochemistry (ICC) and/or polymerase chain reaction (PCR) to assess or rule out a possible clonality of the corresponding cell populations. RESULTS: FNC combined with FC, ICC, and PCR identified 12 cases of reactive, non specific, hyperplasia (BRH), 4 dermatopathic lymphadenopathy (DL), 4 lymph nodal involvement by MF and 1 lymph nodal involvement by cutaneous B-cell lymphoma. CONCLUSIONS: FNC coupled with ancillary techniques is an effective tool to evaluate lymph node status in PCL patients, provided that ROSE and a rational usage of ancillary techniques is performed according to the clinical context and the available material. The method can be reasonably used as first line procedure in PCL staging and follow up, avoiding expensive and often ill tolerated biopsies when not strictly needed.

Lymph node and lymphoid organs fine needle aspiration cytology: historical background.

Lymph node has probably been the first target of Fine Needle Cytology (FNC) and among the latest to be accepted as an affordable diagnostic procedure. In 1912, dr. Hirschfeld performed FNC to diagnose cutaneous lymphomas and other tumours. Subsequently FNC was used to diagnose lymphoblastoma and splenic FNC to diagnose leishmaniasis on Romanowsky-stained smears. One of the first systematic study on lymph node FNC was then performed at John Hopkins Hospital, in Baltimore (USA) using FNC and Romanowsky stain on air-dried smears. In the twenties, two independent groups from Memorial Hospital (New York, USA), worked on FNC of a large scale of different human pathologies. One of this study reported 1,405 diagnoses of cancer and other diseases by means of FNC, mainly performed on lymph nodes (662 cases). In the sixties, at the Karolinska Hospital (Stockholm, Sweden) a group of cytopathologists started a Cytopathology Service available to the whole Institution, which exploited all fields of FNC. Since then, the procedure spread all over the word and nowadays it is routinely used for the diagnosis of different organs and pathologies including lymph node. Distinguished cytopathologists have worked on lymph nodal FNC producing significant advances and highlighting advantages and inevitable limitations of the technique. Despite some persistent criticism, FNC is a generally accepted procedure in the first diagnosis of lymph nodes enlargement. Moreover, numerous studies have demonstrated that vital cells obtained by FNC are excellent samples suitable for molecular evaluation, offering new challenging application to lymph node FNC.

Fine-needle cytology and flow cytometry assessment of reactive and lymphoproliferative processes of the breast.

OBJECTIVE: The breast may be affected by reactive and lymphoproliferative processes such as primary (PBL) or secondary (SBL) lymphoma, reactive intramammary lymph nodes and sclerosing lobulitis; imaging may be not specific and surgical treatment not indicated. We report an experience with fine-needle cytology (FNAC) combined with flow cytometry (FC) and immunocytochemistry (ICC) in the diagnosis of these processes. STUDY DESIGN: Thirty-seven cases comprising intramammary lymph nodes (n = 15), sclerosing lobulitis (n = 2), PBL (n = 11) and SBL (n = 9) are reported. FNAC was used to prepare traditional smears, conventional ICC or FC. Cytological diagnoses were compared to the imaging data, checked by histology or follow-up and statistically evaluated. RESULTS: Imaging was not conclusive in most PBL, SBL, sclerosing lobulitis and some intramammary lymph nodes. FNAC combined with FC and ICC provided a definitive diagnosis of intramammary lymph node, sclerosing lobulitis, PBL and SBL in 18 cases with indication of the specific subtype in 10 cases. Statistical analysis showed 90% sensitivity, 100% specificity, 100% positive predictive value and 89% negative predictive value. CONCLUSIONS: FNAC combined with FC and ICC is a helpful procedure for the diagnosis of reactive and lymphoproliferative processes of the breast. It may prevent unnecessary biopsy and speed up therapeutic procedures.

Impact of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) in lymph nodal and mediastinal lesions: a multicenter experience.

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is an established procedure in lung cancer (LC) staging and in the diagnosis of mediastinal masses. Most of the experiences reported refer to single specialized centers where dedicated teams of endoscopists and pathologists perform the procedure. We report the EUS-FNA experience of a cooperation group involving clinicians and cytopathologists from three hospitals. Fifty-seven consecutive EUS-FNA of mediastinal nodes in LC patients, eight mediastinal and two subdiaphragmatic masses were collected in 3 years. EUS-FNA was performed by two endoscopists and three experienced pathologists. On-site evaluation was performed in all cases by the three cytopathologists. Lymph node negative cases underwent surgery, which confirmed the cytological diagnoses but also detected two false negatives. Four of the 10 EUS cytological diagnoses of mediastinal and subdiaphragmatic masses were histologically confirmed. All EUS diagnoses were blindly reviewed by three pathologists to assess intra and interpersonal reproducibility. FNA-EUS diagnoses were: 10 inadequate (17%), 10 negative (17%), 4 suspicious (7%) and 33 positive (59%). Diagnoses of mediastinal and subdiaphragmatic masses were: relapse of lung carcinoma (3), mesenchimal tumor not otherwise specifiable (3), gastrointestinal stromal tumor (GIST) (1), esophageal carcinoma (2) and paraganglioma (1). The sensitivity attained was 85% and the specificity 100%; revision of the slides demonstrated a significant diagnostic reproducibility of the three cytopathologists (P < 0.5). The sensitivity and specificity attained were similar to those reported in the literature suggesting that experienced cytopathologists and endoscopists from different institutions can employ the same procedure reaching comparable results.

Cutaneous needle track seeding of mesothelioma diagnosed by fine needle aspiration cytology: a case report.

BACKGROUND: Diagnostic and therapeutic procedures for mesothelioma require surgical biopsy or the usage of different-sized needles. Thoracic wall involvement along the surgical or needle tracks has been reported. CASE: A 57-year-old woman who had suffered from non-Hodgkin's lymphoma complained of dyspnea and left pleural effusion. The patient had been treated with chemotherapy and radiotherapy and was in remission since then. Thoracentesis was performed using a 22-gauge needle; the cytologic diagnosis was malignant pleural mesothelioma. Within 2 weeks from thoracentesis, the patient complained of an erythematous swelling in her left chest wall, in the area of the needle track. Fine needle aspiration cytology (FNAC) of the swelling was performed using a 23-gauge needle; 2 smears and a cell block were prepared. Smears showed neoplastic cells in sheets and papillary configuration with the features of mesothelial lineage. Immunocytochemistry showed positivity for calretinin and vimentin. Cytologic slides of the former effusion showed an overlapping of the cytologic and immunocytochemical features. A diagnosis of chest wall involvement from mesothelioma was established and histologically confirmed. CONCLUSION: Chest wall infiltration is a definite risk in the management of pleural mesothelioma, and FNAC is a useful procedure for a timely diagnosis of this ominous complication.

Fine needle aspiration cytology of a cutaneous metastasis from an extraadrenal paraganglioma: a case report.

BACKGROUND: Pheochromocytomas/paragangliomas are rare tumors originating from neuroectodermic cells, which metastasize in only 10% of cases. CASE: A case of cutaneous metastasis of an extramedullary paraganglioma was diagnosed by fine needle aspiration cytology (FNAC). A 39-year-old woman complained of a recently arisen subcutaneous nodule located on the scalp. Two years before she had suffered from a sporadic extraadrenal paraganglioma located on the sacrum, and it had been evaluated by FNAC. Smears were highly cellular and monomorphous; the cells were uniform and mainly isolated with round or ovoid nuclei, dense chromatin and inconspicuous nucleoli, if any. The cytoplasm was ill defined, clear or granular. Oval-spindle-shaped cells and occasional cells with larger nuclei were also observed. Abundant fibrillar material was present in the background, intermingled with the surrounding cells. The immunocytochemical staining performed on cell block sections showed negativity for CK20, HMB45 and LCA and positivity for chromogranin and S100. The cytologic diagnosis was a neuroendocrine tumor, consistent with a metastasis from the former sacral paraganglioma. CONCLUSION: On conventional samples the cytologic features of paraganglioma are typical enough to allow a cytologic diagnosis of a neuroendocrine tumor; this neoplasm should be considered in the differential diagnosis, even in such unusual locations, because of its unpredictable biologic behavior.

Fine needle cytology and flow cytometry of ectopic cervical thymoma: a case report.

BACKGROUND: A case of ectopic cervical thymoma (ECT) in which fine needle cytology (FNC) and flow cytometry (FC) have orientated the cytologic diagnosis, is described. CASE: A 57-year-old woman underwent FNC of a right latero-cervical nodule. The smear showed a dispersed lymphoid-cell population; therefore, a second FNC was used for FC and to prepare a cell block. Smears were highly cellular. Cells were medium or large sized, with scanty cytoplasm and nuclei with dispersed chromatin; large cells showed evident nucleoli. Immunohistochemistry on additional smears were positive for CD45RO and Ki67 in most of the cells, and negative for CK pan, CD20, thyreoglobulin and calcitonin. FC showed the following phenotype: CD2/CD3/CD7 = 67%, CD10 = 61%, CD4/CD8 = 62%. CD19 and light chains were not expressed. A diagnosis of T-cell lymphoid proliferation was made and ECT was suggested; histological diagnosis was cervical ectopic benign type B1 thymoma. CONCLUSION: FC may support the FNC diagnosis of ECT because of the specific phenotype of lymphoid cells showing the profile of "polyclonal" (CD2/CD3/CD7+) and thymic T-cells (CD10+, CD4/CD6+). FNC and FC may suggest the diagnosis of ECT even in the absence of detectable epithelial cells.

Cytologic, flow cytometry, and molecular assessment of lymphoid infiltrate in fine-needle cytology samples of Hashimoto thyroiditis.

BACKGROUND: The thyroidal lymphoid infiltrate (TLI) in Hashimoto thyroiditis (HT) represents the substrate from which thyroid lymphoma may arise. The objective of the current study was to classify the TLI in HT by comparing the cytologic features with flow cytometry (FC) data and evaluating the kappa/lambda light chain ratio and its molecular assessment. METHODS: Fine-needle aspiration cytology (FNAC) was performed in 34 patients with HT with nodular or diffuse palpable enlargement of the gland. Two or 3 passes were performed to prepare traditional smears, FC, and immunophenotyping, and RNAlater suspensions for molecular assessment. FC was performed using the following antibodies: CD3, CD5, CD4, CD8, CD10, CD19, and kappa and lambda light chains. In 4 cases, high molecular weight DNA was extracted and used for polymerase chain reaction (PCR) to amplify the variable diversity joining region of the heavy chain immunoglobulin (Ig) genes (IgH). Statistical analysis was performed to evaluate possible associations between clinical ultrasound presentation, cytologic pattern, and TLI phenotype. Light chain expression was evaluated as the percentage of the expressing cells (20%) and as the kappa/lambda ratio. RESULTS: Smears were classified as "lymphocytic," "lymph node-like," or "mixed." FC demonstrated T cells (CD3 positive [+], CD5+) in all cases, and T cells and B cell (CD19+, CD10+/-) lymphocytes in 22 cases. Light chains were expressed in 30 cases (in <20% of the gated cells in 13 cases and in >20% of the gated cells in 17 cases). Five cases demonstrated small kappa/lambda ratio imbalances and PCR analysis demonstrated diffuse bands in the gel and Gaussian curves at the heteroduplex. Statistical analysis indicated significant associations between the "lymphocytic" pattern and T-cell phenotype and between the "lymph node-like" pattern and B-cell phenotype. A significant association also was observed between light chain restriction and low light chain expression (P < .005). CONCLUSIONS: The cytologic pattern of TLI in HT is quite representative of the clinical presentation and phenotypic cell type. Small light chain imbalances are not sustained by heavy chain Ig gene (IgH) rearrangements. FNA coupled with FC may contribute to making the distinction between florid TLI and non-Hodgkin lymphoma.

Fine-needle aspiration cytology in the follow-up of Hodgkin lymphoma.

Hodgkin lymphoma (HL) is characterized by long survival and risk of relapse and second neoplasm. The aim of this study is to evaluate the possibility of improving the accuracy of fine-needle cytology (FNC) in HL follow-up using Power Doppler ultrasound (US) assistance and immediate microscopic evaluation (ICE). The study was performed in two consecutive groups of 200 FNC in HL patients. In the first group FNC of palpable lymph-nodes or extra lymph-nodal masses were performed without US assistance except for impalpable and/or deep located masses (nonassisted group); In the second group, all the FNC were performed under Power Doppler US assistance with ICE and immediately repeated in inadequate cases (assisted group). Cytological diagnoses were controlled by histology (61) or clinical follow-up (69); sensitivity and specificity were calculated in the two groups and to evaluate the effect of Power Doppler alone, adequate cases were compared with the total number of FNC in each of the two groups.FNC identified 90 negative cases, 3 false negatives, 70 HL relapse, 16 inadequate and 14 suspicious; second neoplasia were diagnosed in 12 cases and all histologically confirmed. Sensitivity and specificity were 64 and 84% in the nonassisted group and 86 and 94% in the assisted group and there were significant differences between the number of adequate cases v.s. the total number of FNC in each of the two groups. Sensitivity and specificity in assisted FNC are higher than in nonassisted ones. The main advantage of assisted FNC in the follow-up of HL is to produce accurate diagnoses avoiding invasive biopsies.

Pulmonary langerhans cell histiocytosis (histiocytosis X) on bronchoalveolar lavage: a report of 2 cases.

BACKGROUND: Pulmonary Langerhans cell histiocytosis (PLCH) is an interstitial lung disease characterized by bilateral nodular and cystic lesions. Clinically it seems to be a reactive process related to cigarette smoking. CASES: In 2 cases of PLCH, cytologic and immunocytochemical evaluation of bronchoalveolar lavage (BAL) fluid was successfully used for the diagnosis of PLCH. Two heavy smokers complained of fever, cough and debilitation. Serologic and hematologic values were normal. In both cases radiography and computed tomography (CT) were similar, showing multiple bilateral nodular or cystic lesions in the middle and upper lung zones. Cytospins obtained from BAL were Papanicolaou and May-Grünwald-Giemsa stained; others were immunostained with cytokeratin cocktail, CD1a and S-100. Cytospins showed a monomorphous and dispersed cell population consisting ofmononucleated or binucleated and occasionally multinucleated histiocytes. Single cells showed wide, well-defined, acidophilic cytoplasm and oval or kidney-shaped, vesicular nuclei with irregular shapes, evident nucleoli and frequent grooves and indentations. Immunocytochemical staining showed diffuse cytoplasmic positivity for S-100 and CD1a and negativity for cytokeratin; only the few cylindrical cells present in the cytospins were positive for cytokeratin. In both cases the cytologic diagnosis of PLCH was confirmed by subsequent CT and clinical follow-up. CONCLUSION: Cytologic and immunocytochemical evaluation of BAL fluid permits a definitive diagnosis of PLCH. This cytologic diagnosis is clinically relevant because it permits surgical biopsy to be bypassed and allows waiting for a possible spontaneous or pharmacologic resolution.

Flow cytometry phenotypization of thyroidal lymphoid infiltrate and functional status in Hashimoto's thyroiditis.

OBJECTIVE: To evaluate the thyroidal lymphoid infiltrate (TLI) in thyroidal functional status (TFS) for differences among patients with Hashimoto's thyroiditis (HT). STUDY DESIGN: Flow-cytometry (FC) was applied to thyroidal fine-needle cytology samples in 57 patients. TLI was analyzed using a fluorescence-activated cell sorter (FACS) scan and fluorescence antibodies CD3, CD4, CD5, CD8, CD10, and CD19 and kappa and lambda light chains. TFS was determined by serum thyroid-stimulating hormone (TSH), FT3 and FT4 immunoassays, in specific clinical settings, to classify the cases as hyperthyroid, euthyroid and hypothyroid. FC assessment was then compared with the corresponding TFS. RESULTS: B-lymphocytes were present in 44 cases (77%). T-lymphocytes were present in all the cases; CD4/CD8 = 2:1 ratio was observed in 16 euthyroid, 1 hyperthyroid and 3 hypothyroid; CD4/CD8 > or = 3:1 ratio in 22 euthyroid, 2 hyperthyroid and 2 hypothyroid cases; CD4/CD8 < or = 1:1 ratio in 1 euthyroid, 3 hyperthyroid and in 7 hypothyroid cases. Grouping hyperthyroid and hypothyroid cases, a significant association was observed with the CD4/CD8 < or = 1:1 ratio (p < 0.01). CONCLUSION: Intrathyroidal CD4/CD8 < 1:1 ratio might be the expression of intense apoptosis in the early phases of HT, generally followed by the restoration of CD4/CD8 balance; persistence of increased intrathyroidal CD8 might be related to intense thyroidal damage and thus an increasing risk of hypothyroidism.

Fine needle cytology of endometriosis: experience with 10 cases.

OBJECTIVE: To evaluate whether commonly used cytologic criteria for the diagnosis of endometriosis are sufficiently specific, to assess the possible role of special methods in the differential diagnosis and to assess the clinical meaning and drawbacks of a cytopathologic diagnosis of endometriosis by fine needle aspiration. STUDY DESIGN: We retrieved 10 cases of endometriosis from our files that had been diagnosed primarily by fine needle cytology (FNC) with subsequent tissue study. In some cases additional cytospin preparations and/or smears had been used for cytochemistry (periodic acid-Schiff stain, mucicarmine) or immunocytochemistry (pan-cytokeratin, cytokeratin 7, vimentin, CD10) using a 3-step streptavidin-biotin-immunoperoxidase reaction. RESULTS: The cell pattern and immunocytochemical profile of the cases suggested a diagnosis of endometriosis. All cases were histologically confirmed. CONCLUSION: With optimal preparations a confident cytologic diagnosis of endometriosis may be made with ease, permitting correct treatment of the disease and, in selected cases, planning of preoperative pharmacologic therapy.

Metaplastic breast carcinoma on fine-needle cytology samples: a report of three cases.

Metaplastic breast carcinoma (MBC) may have a varied presentation on fine-needle cytology samples. We herewith describe three cases of MBC found in our series. One of these cases showed a peculiar mixture of malignant ductal, apocrine type, and squamous epithelial cells with fascicles of spindle cells with variable degree of atypia and was diagnosed as metaplastic carcinoma of the carcino-sarcomatous type. The other two lesions were characterized by an abundant chondroid extracellular matrix to which were variably admixed carcinomatous and chondroid-type cells, with variable degree of atypia. Both these latter cases were defined as matrix-producing metaplastic carcinomas. Because of the various presentation of MBC on fine-needle cytology samples and the possible influence of needle "sampling" on the cytological specimen, the spectrum of differential diagnoses to be considered may encompass a number of benign and malignant entities, like keratinous subareolar cysts, malignant fibroepithelial lesions with myxo-chondroid stroma, and true sarcomas of the breast, with cartilaginous metaplasia. It is the Authors' feeling that, with optimal samples, the cytomorphological findings of this rare variant of breast carcinoma permit its accurate pre-operative diagnosis.

Hemophagocytic histiocytosis diagnosed by fine needle aspiration cytology of the spleen. A case report.

BACKGROUND: Hemophagocytic histiocytosis (HPS) is an idiopathic, familial or secondary syndrome characterized by mature histiocytes causing intensive erythrophagocytosis. CASE: A 2-month-old male suffering from autoimmune hemolytic anemia, fever, jaundice and hepatosplenomegalia underwent fine needle aspiration cytology of the spleen. Aspiration was performed using a 23-gauge, short needle with a subcostal approach. The smear showed a monomorphous cell population of mature histiocytes with marginal nuclei and wide, well-defined cytoplasm. The cytoplasm was microvaculated and often contained > or = 1 erythrocytes and occasional lymphocytes. Immunostaining performed on cytospin samples showed diffuse positivity for alpha-1-antichymotrypsin and S-100. Differential diagnosis with malignant histiocytosis, Langerhans histiocytosis and sinus histiocytosis with massive lymphadenopathy was established. HPS was diagnosed because of the cytologic and immunocytochemical features and clinical data. CONCLUSION: HPS may be diagnosed using fine needle aspiration of the spleen when other biopsy samples have been unsuccessful. Cytologic, diagnosis of HPS should always be considered in a specific clinical setting, because early treatment can often save the patient's life.

p27(Kip1) expression and grading of breast cancer diagnosed on cytological samples.

The progressive reduction in p27(Kip1) (p27) protein immunohistochemical staining with increasing histological grading is a well-established finding occurring in breast cancer, and its role as diagnostic complement and prognostic marker has been thoroughly evaluated. To clarify whether this test may be applied to breast cytopathology, we performed p27 immunostaining on fresh fine-needle cytology (FNC) samples from 10 benign and 40 malignant breast lesions. On average, p27 immunostaining was significantly lower in carcinomas than in benign lesions (P < 0.005). In particular, among carcinomas, p27 immunostaining progressively reduced from well-to poorly differentiated lesions (G1 vs. G2, P < 0.05; G1 vs. G3, P < 0.001; G2 vs. G3; P < 0.001). A similar trend was noted in a subgroup of 20 matched FNCs and histological samples of breast carcinomas, when p27 immunostaining on FNCs was stratified according to the histological grading (G1 vs. G2, P = 0.18; G1 vs. G3, P < 0.05; G2 vs. G3, P < 0.05). In addition, p27 immunostaining on FNCs showed a good positive correlation with that on histology (Spearman R = 0.58; P < 0.01), with a diagnostic concordance between samples of 85%, by using the standard 50% positive cell cutoff. Taken in concert, our data suggest that p27 immunostaining is a reliable marker of tumor cell differentiation in breast cytopathology as well as in histopathology. Accordingly, staining FNCs for p27 may be an useful complement in addition to cytological grading in the preoperative assessment of breast cancer.