Cytodiagnosis of classic lobular carcinoma and its variants.

The well-known cytologic features of lobular carcinoma traditionally consist of modest cellularity and small, atypical cells lying singly or in small groups. However, lobular carcinoma is a common pitfall in the cytodiagnosis of breast lesions. Knowledge of its varied histologic appearance can help to prevent diagnostic difficulties. Among 55 consecutive cases of breast needle aspirates with histologic follow-up, 9 lobular carcinomas were identified. The surgical material was examined for the following histologic variants: (1) classic, (2) solid, (3) alveolar, and (4) mixed; it was correlated with the cytologic findings. Pure, classic lesions were the most likely cause of false-negative diagnoses. Two of nine lobular carcinomas were diagnosed as benign due to scant cellularity and cell smallness. Four of nine were cytologically misclassified as ductal type due to more abundant cellularity and larger cells. This could be attributed to the predominant alveolar or solid patterns present in three cases. Only three of nine were accurately classified as lobular carcinoma, and all had a significant classic histologic element. Another important feature that is highly suggestive of lobular carcinoma is the presence of cytoplasmic vacuoles. They were overlooked in three of four cases. This study suggested that the traditional cytologic features of lobular carcinoma are present only in tumors with a predominantly classic histologic pattern. Awareness of the variant patterns and their cytologic features, including more abundant cellularity, larger cells and clusters, and cytoplasmic vacuoles, will aid in correct classification.     

Fine needle aspiration cytologic findings of breast mucinous neoplasms: differential diagnosis between mucocelelike tumor and mucinous carcinoma

OBJECTIVE: To report the cytologic findings of mucocelelike tumor and mucinous carcinoma. STUDY DESIGN: All mucinous neoplasms diagnosed by fine needle aspiration and confirmed by histologic examination were reviewed to detect the cytologic findings helpful for the differentiation. The cytologic findings were correlated with the histologic findings. RESULTS: Cytologically, mucinous carcinomas were highly cellular and showed many single epithelial cells and variably formed epithelial cell clusters in abundant extracellular mucin. Malignant cells exhibited round, atypical nuclei; granular chromatin; and small nucleoli. Mucocele like tumor showed low cellularity with scanty, monolayered, small sheets of epithelial cells and abundant, extracellular mucin. Myoepithelial cells were present within the epithelial cell sheets. Tumor cells were usually small, with uniform, round nuclei; fine chromatin; and absence of nucleoli. CONCLUSION: Cytologic findings of mucocelelike tumor and mucinous carcinoma were different in cellularity, shape of cell clusters and nuclear features, although mucocelelike tumors having a carcinoma component were similar to mucinous carcinoma. Awareness of the cytologic findings of breast mucinous neoplasms is important to make a specific diagnosis.     

Identification of types and primary sites of malignant tumors by examination of exfoliated tumor cells in serous fluids. Comparison with the diagnostic accuracy on small histologic biopsies

The accuracy of identification of tumor type and primary site of malignant tumors by examination of exfoliated tumor cells was cytologically studied in 448 malignant effusions from 366 patients for whom the primary tumor site had been confirmed by histology. Ninety-seven corresponding small biopsies from metastases were separately reviewed histopathologically. In four fluids, the cells were too scanty or too poorly preserved for tumor typing. The cytologic tumor typing was performed with nearly 100% accuracy in the remaining 444 fluids, except for those of intermediate-cell anaplastic carcinomas (0 of 3) and poorly differentiated squamous (epidermoid) carcinomas (1 of 5). Adenocarcinoma was correctly identified in 98% of 285 fluids, large-cell carcinoma in 97% of 108 fluids, oat-cell carcinoma in 94% of 16 fluids, well-differentiated (keratinizing) squamous carcinoma in 100% of 3 fluids, malignant lymphoma in 100% of 22 fluids and sarcoma in 100% of 2 fluids. The criteria and the failures are discussed at length. In the investigation of the accuracy of cytologic and histologic diagnoses with respect to the primary tumor site, tumors with variable sites of origin (sarcomas and lymphomas) and those with usually singular sites of origin (e.g., small-cell anaplastic carcinoma of the lung) were excluded, leaving 387 cytologic and 83 histologic specimens available for review. The breast as a primary site was correctly identified in 70% of both the cytologic and histologic specimens; the primary cytodiagnostic criteria included a uniform cell pattern, finely granular chromatin, dense cytoplasm and cell balls with smooth borders. Ovarian primaries were correctly identified in 70% of the fluids and 83% of the biopsy samples on the basis of very irregular clusters of large pleomorphic tumor cells, large nucleoli and psammoma bodies. Lung primaries, identified in 50% of the fluids and 29% of the biopsy samples, showed quite variable cell patterns, most often including large pleomorphic cells with or without mucus formation and prominent multinucleation. Gastric cancers of the diffuse type were accurately identified in 52% of the corresponding fluids, which showed mainly isolated cells with dense cytoplasmic rims, occasional signet-ring cells, "embryo-shaped" nuclei, marked hyperchromasia and densely granular chromatin.(ABSTRACT TRUNCATED AT 400 WORDS)     

Value of fine needle aspiration cytology of the breast, with an emphasis on the cytodiagnosis of colloid carcinoma.

The fine needle aspiration (FNA) cytologic evaluation of 6,941 lesions of the breast was reviewed, with an emphasis on the cytodiagnosis of colloid carcinoma. The most common benign breast diseases in this series were fibroadenomas, cysts and fibrocystic conditions. All cases with an FNA diagnosis of suspicious were biopsied; a number of these were found to be carcinoma of the breast. In cases with an FNA diagnosis of carcinoma of the breast, a plan of management was immediately adopted on the basis of that diagnosis. Thirteen cases of colloid (mucinous) carcinoma of the breast were diagnosed by FNA cytology; in all, the cytodiagnosis was confirmed by the subsequent histologic diagnosis. The distinctive cytologic criteria that may be useful for making an FNA diagnosis of colloid carcinoma of the breast are discussed, and the FNA differences between the pure and mixed types of colloid carcinoma are noted.     

Cytologic diagnosis of the papillary variant of renal-cell carcinoma

The papillary variant of renal-cell carcinoma is characterized by distinctive histologic, clinical and angiographic features. A study was undertaken to delineate the cytologic features of this tumor as it is encountered in cellular samples. Cytologic specimens containing tumor cells from eight patients who underwent resection for papillary renal-cell carcinoma were examined and compared to corresponding cytologic samples obtained from ten other patients who had nonpapillary renal-cell carcinoma. The cytologic appearance of papillary renal-cell carcinoma, which is deceptively benign, is marked by distinctive papillary structures that often resemble branched chains. The cells are usually small and contain uniform nuclei; numerous macrophages with foamy cytoplasm are often found in the background. These cytologic features were not observed in the cellular specimens from the nonpapillary renal carcinomas. We conclude that papillary renal-cell carcinoma can be confidently recognized in cytologic specimens.     

Fine needle aspiration of breast carcinoma: a preliminary cytoprognostic study

A cytologic grading method for fine needle aspiration smears was applied to 178 histologically confirmed breast carcinomas. Grade I defined a well-differentiated carcinoma, grade II a carcinoma with pleomorphic tumor cells and grade II an anaplastic carcinoma. The cell-to-cell relationship (topography) and the cytologic criteria contributed to the grading. Special attention was paid to grade III tumors, which have an unfavorable prognosis. The correlation of grading with the clinical course of the disease was evaluated after a 12-month followup. In 4% of the patients classified as having grade I disease, 8.9% as having grade II and 66% as having grade III, local recurrence of disease, metastasis or death was observed within one year. The contribution of cytologic grading to the prognosis of breast cancers is discussed.     

Cytology of argyrophilic carcinoma of the breast

Aspirations of breast lesions from 57 patients were studied by evaluating Grimelius-stained smears in order to determine the cytologic features of argyrophilic carcinoma and the reliability of argyrophilia as a characteristic of malignancy. The cytologic preparations were compared with histologic material. Sixteen benign lesions, 24 carcinomas correctly diagnosed by cytology and 5 carcinomas with technically inadequate smears were argyrophil negative. Five of 12 carcinomas with equivocal cytology were argyrophilic. There was perfect to case-to-case correlation between argyrophilia seen on histologic slides and on smears. The smears of the 5 argyrophilic carcinomas and 2 of the argyrophil-negative carcinomas with equivocal cytology shared features in common not seen in the other 50 smears: elongated cells with eccentric, round-to-oval nuclei and granular or opaque cytoplasm. These features can alert the pathologist to the possibility of malignancy in smears with equivocal cytology. A positive stain for argyrophilia will further increase the index of suspicion.     

Cytologic evaluation of prognostic markers in breast carcinoma

To type breast carcinomaon on fine needle aspiration cytology (FNAC) material and correlate the results with histologic typing, to grade breast carcinoma on FNAC material and correlate the findings with Bloom-Richardson histologic grading, and to determine the estrogen receptor (ER) status in cases of breast carcinoma by immunocytochemical (ICC) staining of FNA cytologic material and correlate the findings with ER status, as determined by immunohistochemical (IHC) staining of tissue sections. STUDY DESIGN: Seventy-seven cases of breast carcinoma diagnosed on FNAC formed the basis of this study. Typing was done in all cases on the basis of cytologic features and grading in 62. (Fifteen cases were special types of breast carcinoma). In all cases, ER status was determined by immunostaining of cytologic smears. Results of tumor typing, grading and ER status on cytologic material were compared with the results of histologic typing, grading and immunostaining of histologic material obtained from mastectomy or wide excision specimens. RESULTS: Tumor typing was accurate in 73 of 77 cases (94.8%). Fifteen of 18 cases that were cytologically grade 3 were confirmed on histology, while 3 proved to be grade 2. Of 40 cytologic grade 2 cases, 26 were confirmed on histology, while 14 cases were grade 3. Three of 4 cytologically grade 1 cases were confirmed on histology while 1 was grade 2. The overall accuracy for cytologic grading was 71% (44 of 62 cases). Thirty-seven of 40 ER-positive cases (92.5%) were labeled ER positive on ICC. One case was ER negative on cytology, while in 2 cases the cellularity of the cytologic smear was insufficient to assess ER expression. Thirty-seven cases were negativefor ER on IHC. Nine of these showed ER positivity on ICC, 26 were negative, and 2 had cellularity that was inadequate for assessment of ER. Sensitivity and specificity rates for ER detection on ICC were 97.4% and 74.3%, respectively. CONCLUSION: Tumor typing, grading and evaluation of ER status on FNA C material in breast carcinomas are simple, quick and moderately reliable techniques that compare and correlate favorably with histologic typing, grading and ER status on IHC.     

Stereotaxic fine needle aspiration cytology of clinically occult malignant and premalignant breast lesions

Stereotaxic fine needle aspiration (FNA) cytology was used to study clinically occult (nonpalpable) breast lesions in 114 consecutive patients with mammographically suspicious findings prior to excisional biopsy. The aspirate contained insufficient material for cytologic evaluation in 15 cases (13.2%), which were histologically diagnosed as benign (7 cases), atypical hyperplasia (7 cases) or carcinoma in situ (1 case). The cytologic findings indicated a benign lesion in 77 cases (67.5%), which were histologically diagnosed as benign (71 cases) or atypical ductal hyperplasia (6 cases). The cytologic sample showed atypia in eight cases (7.0%), which were histologically diagnosed as severe atypical ductal hyperplasia (three cases), carcinoma in situ (one case) or proliferative fibrocystic disease (four cases). In the eight cases (7.0%) cytologically interpreted as probably malignant, histology confirmed six invasive carcinomas, one carcinoma in situ and one fibrocystic disease. Of six cases (4.4%) cytologically reported as malignant, five were histologically diagnosed as invasive carcinoma and one as carcinoma in situ. Overall, stereotaxic FNA cytology reported as malignant or probably malignant 14 of the 15 cases with a histologic confirmation of malignancy, for a sensitivity of 93.3%. Cytology correctly identified 78 of the 83 histologically negative cases, for a specificity of 94.0%. The 16 cases histologically diagnosed as ductal hyperplasia, which carries a high risk for subsequent malignancy, were studied in detail in an effort to define histologic and cytologic criteria for this entity. Using selected histologic criteria, 11 of these cases were graded as showing mild-to-moderate atypical hyperplasia and 5 as showing severe atypical hyperplasia. Three of the latter cases were similarly identified by an analogous cytologic grading; the other two cases had insufficient cytologic samples. The total results in this series of 114 cases support the use of stereotaxic FNA cytology in the diagnosis of these nonpalpable breast lesions, examples of which are illustrated. In particular, it may help to raise the low specificity yielded by mammography alone, which would represent a significant advance for the patient in terms of the accuracy, expediency and reduced cost of diagnosing these lesions.     

Immunohistochemical study of lysozyme, alpha 1-anti-chymotrypsin, tissue polypeptide antigen, keratin and carcinoembryonic antigen in effusion sediments

The cellular sediments of 42 malignant and 16 benign effusions (58 cases) were studied using the immunoperoxidase technique. Serial sections of formalin-fixed, paraffin-embedded residual sediments of effusions, sent for routine cytologic examination, were studied by commercially available polyclonal antisera against lysozyme, alpha 1-anti-trypsin, alpha 1-anti-chymotrypsin, tissue polypeptide antigen (TPA), a wide-spectrum anti-keratin, carcinoembryonic antigen (CEA) and, in single cases, thyroglobulin and prostate-specific antigen. A final definite diagnosis from histologic study of biopsy or autopsy specimens was known in all cases. All carcinomas, the mesotheliomas and the reactive mesothelial cells showed a positive reaction for TPA and, partly, the wide-spectrum keratin. Lysozyme could be demonstrated in the cells of the one proven malignant fibrous histiocytoma; all malignant epithelial cells were negative. Alpha 1-anti-chymotrypsin and alpha 1-anti-trypsin showed similar reactions: they were often positive in carcinoma cells of the breast, the bronchial system and the pancreas, in contrast to a mostly negative reaction in carcinomas of the stomach and ovary. CEA showed considerable differences; it was always negative in benign and malignant mesothelial proliferations but mostly positive in carcinomas of the stomach, pancreas and bronchial system. It was only positive in less than 20% of the carcinomas of the breast and always negative in the proven malignant effusions of primary carcinomas of the ovary and prostate. Studying a combination of several tumor markers is possible in serial paraffin-embedded sections and may be a valuable criterion in the cytologic diagnosis of effusions.     

The diagnostic reliability of cytologic typing in primary lung cancer with a review of the literature

To evaluate the growing tendency in recent years to attribute more diagnostic reliability to cytologic methods, we investigated the accuracy of cytologic typing in specimens obtained from bronchopulmonary material by five different clinical sampling methods, comparing the cytologic diagnoses with the known histologic diagnoses. The study consisted of 232 cytologic specimens from 157 cases of primary lung cancer. Of the 232 specimens, 173 (75%) were correctly typed and 59 (25%) incorrectly typed with respect to the appropriate histologic diagnoses. When all sampling methods were considered together, the study demonstrated that well-differentiated epidermoid carcinoma and "oat cell" and spindle-polygonal anaplastic carcinomas yielded high cytologic typing accuracies. In poorly differentiated tumors, bronchioloalveolar cell carcinoma and bronchogenic adenocarcinoma, the correct cytologic typing was much lower. The different tumor types and their degrees of differentiation seem to be the decisive factors in cytologic typing accuracy. The findings of this study were compared with those of others and were found to be consistent with the results of even larger series of cases. For some types the typing accuracy was higher than that reported in other series, whereas for other types, e.g., adenocarcinomas, it was lower.     

Apoptosis in breast cancer

OBJECTIVE: To evaluate apoptotic rates on fine needle aspiration (FNA) samples of infiltrating duct carcinoma of the breast and to determine whether cytologic grading improved with consideration of the apoptotic rate in comparison with histologic grading. STUDY DESIGN: We studied 35 women who underwent mastectomy following an FNA diagnosis of infiltrating ductal carcinoma. Concordance between cytologic and histologic grades was calculated. Next, cytologic grades were considered with the apoptotic rates and compared with the histologic grades. RESULTS: An overall concordance of 82.9% was noted between the cytologic and histologic grading systems, with maximum concordance in grade 1 and minimum in grade 3 breast cancers. A highly significant difference in the apoptotic rates, as calculated on cytology, existed between the three histologic grades, indicating a significant increase in apoptosis with rising histologic grade. Applying multiple regression analysis, a significant improvement of cytologic grade with consideration of the apoptotic rate was observed. CONCLUSION: Employing histologic grade as the yardstick, cytology was less sensitive for the purpose of grading breast ductal carcinoma. However, by considering the apoptotic rates, the sensitivity of cytologic grading significantly rose in relation to histologic grade. Larger studies are required to determine whether apoptosis can be incorporated into the existing cytologic grading systems to increase their sensitivity.     

Membrane connectivity estimated by digital image analysis of HER2 immunohistochemistry is concordant with visual scoring and fluorescence in situ hybridization results: algorithm evaluation on breast cancer tissue microarrays

Because metaplastic carcinoma of the breast encompasses a great variety of histopathology, diagnostic challenges abound, especially within the realm of cytology. The authors compiled and studied an eight-case series comprised of metaplastic breast carcinomas and lesions initially suspicious cytologically for metaplastic carcinoma in order to assess the degree of cytologic-histologic correlation and to identify recurring problematic themes surrounding the cytology-based diagnosis of this neoplasm. The cytologic and histologic slides from eight cases suspicious for metaplastic breast carcinoma diagnosed by fine needle aspiration (FNA) were collected and analyzed through a seven-year retrospective search of case files at our institution. Based on cytologic characteristics, the cases were separated into three groups. Group 1 consisted of three cases presenting with poorly differentiated adenocarcinoma and squamoid components on FNA. Group 2 was composed of two cases that featured a monophasic, malignant ductal cell population on cytology, while the cytologic specimens for the third group of cases presented with a mesenchymal component with or without a malignant glandular constituent. Cytologic-histologic correlation was present in two of three cases demonstrating a mesenchymal component, and there was 100% sensitivity in the cytologic detection of those mesenchymal elements. However, in only one of three cases was there an accurate cytologic diagnosis of metaplastic carcinoma when squamoid changes were present on FNA. Both cases demonstrating only malignant glandular elements on cytologic specimens revealed an additional component of malignant squamous differentiation upon the examination of mastectomy-derived tissue. These results indicate that squamous-like changes identified on FNA should be interpreted with caution and that sampling error remains a problematic recurrence in cytology. Regardless, there appears to be promise concerning the accurate cytologic diagnosis of metaplastic carcinoma when the lesion is characterized by a mesenchymal component. A study implementing a larger case number is essential in determining the significance of these findings.     

Stromal fibroblasts present in invasive human breast carcinomas promote tumor growth and angiogenesis through elevated SDF-1/CXCL12 secretion

Fibroblasts often constitute the majority of the stromal cells within a breast carcinoma, yet the functional contributions of these cells to tumorigenesis are poorly understood. Using a coimplantation tumor xenograft model, we demonstrate that carcinoma-associated fibroblasts (CAFs) extracted from human breast carcinomas promote the growth of admixed breast carcinoma cells significantly more than do normal mammary fibroblasts derived from the same patients. The CAFs, which exhibit the traits of myofibroblasts, play a central role in promoting the growth of tumor cells through their ability to secrete stromal cell-derived factor 1 (SDF-1); CAFs promote angiogenesis by recruiting endothelial progenitor cells (EPCs) into carcinomas, an effect mediated in part by SDF-1. CAF-secreted SDF-1 also stimulates tumor growth directly, acting through the cognate receptor, CXCR4, which is expressed by carcinoma cells. Our findings indicate that fibroblasts within invasive breast carcinomas contribute to tumor promotion in large part through the secretion of SDF-1.     

Diagnostic accuracy of squamous cervical lesions studied in spatula-cytobrush smears

The cytologically positive cases found in 25,300 cervical smears of spatula samples and 6,168 smears prepared by combined spatula-Cytobrush sampling were analyzed. The diagnostic accuracy (the correlation between the cytologic and histologic diagnoses) was the same for both types of sampling. As to the histologic diagnosis, the rates of severe dysplasia, carcinoma in situ and squamous carcinoma in the spatula-Cytobrush group were more than twice as high as in the spatula group. In the spatula group, the majority of abnormal cells was of the mature type. In the spatula-Cytobrush group, the majority of smears contained a mixture of immature and mature abnormal cells. The more immature lesions, which are often located higher in the endocervical canal, seem to be better sampled by the Cytobrush. The results indicate that the Cytobrush reaches areas that a spatula cannot reach, resulting in a higher diagnostic efficiency.     

Cytologic uniformity of breast cancer from different localizations: a pattern analysis study.

Using cytologic pattern analysis it is shown that regions of different histologic structure in one breast cancer are of cytologic homogeneity. The so-called PFORM -- the quotient of the total outline length of DNA-particles to the nuclear area -- gives an objective cytologic parameter which is independent of DNA content of cancer cells. This objective parameter together with the subjective cytologic parameters described earlier may be a better basis for describing the biologic behavior of breast cancer than histologic structure which is inhomogeneous very often in a lump.     

Pemphigus vulgaris and microinvasive squamous-cell carcinoma of the uterine cervix

Although patients with disseminated pemphigus vulgaris may have involvement of the uterine cervix, such involvement is often detected only after vaginal discharge or bleeding. When a cervical smear is obtained, distinctive cytologic abnormalities may be observed; these may be attributed to the changes of pemphigus or to an associated reparative/inflammatory reaction. This study documents the first two cases of microinvasive squamous-cell carcinoma of the uterine cervix developing in association with uterine cervical pemphigus. The gross pathologic, cytologic and histologic features of these lesions are illustrated. The cytologic criteria that may be helpful in distinguishing between cells derived from microinvasive squamous-cell carcinoma and pemphigus of the uterine cervix are described.     

Glassy cell carcinoma of the uterine cervix. Report of a case with cytohistologic and immunohistochemical study

BACKGROUND: Glassy cell carcinomas of the uterine cervix are poorly differentiated carcinomas composed of cells with a large, round to oval nucleus containing one or multiple prominent nucleoli, finely vacuolated eosinophilic to amphophilic cytoplasm and distinct cell borders. These cells occur in sheets and chords, with fibrovascular septae presenting a mixed inflammatory infiltrate. This neoplasm has a poor response to radiotherapy and a worse prognosis than the usual types of adenocarcinoma and squamous cell carcinoma. There are few reports on the cytologic and histopathologic features of this neoplasm. CASE: A 56-year-old woman presented with a large, exophytic cervical tumor. Exfoliative cytology showed clusters of cells and single cells with large, round to oval nuclei, with one or multiple nucleoli and moderate to large, finely granulated cytoplasm with distinct cell borders. The background of the smears had a polymorphous inflammatory infiltrate, necrotic debris and proteinaceous material. A high mitotic rate was observed, as were rare bizarre and atypical multinucleated cells. There was no evidence of koilocytes. These findings were highly suggestive of glassy cell carcinoma and were confirmed by the histologic and immunocytochemical findings, with positivity for cytokeratin (MNF116), vimentin and carcinoembryonic antigen and negativity for HMB-45. CONCLUSION: Glassy cell carcinoma of the cervix presents a cytologic picture that can be highly suggestive of the diagnosis in typical cases; however, in difficult cases ancillary techniques, such as immunocytochemistry, as well as histologic findings might confirm the diagnosis.     

Morphology of healthy human parathyroid glands in cytologic smears

OBJECTIVE: To compare the morphology of different parenchymal cell types in healthy human parathyroid glands (HPGs) in cytologic smears with their structure on histologic sections and to establish criteria for their recognition in smears. STUDY DESIGN: The HPGs of 47 subjects (27 females and 20 males) were incidentally removed during surgery on the thyroid gland. The tissue of glands with a normal macroscopic and microscopic appearance was analyzed in cytologic smears and on histologic sections. RESULTS: In cytologic smears (as well on histologic sections), dark and light chief cells predominated. Dark chief cells, which were more numerous than light ones, had a smaller nucleus without a visible nucleolus. The nucleus of light chief cells was larger with 1 or 2 nucleoli visible. The cytoplasm of both types of chief cells was poorly defined, grey-blue and often vacuolated. In the smears, the cytoplasm of oxyphilic cells was dense, gray-rose and well defined. In dark oxyphilic cells, the nuclei were smaller and without a visible nucleolus. Light oxyphilic cells had a larger nucleus and visible nucleolus. CONCLUSION: The identification and distribution of 4 parenchymal cell subtypes in the smears of pathologically altered HPGs may yield insights into the possible role of these cells in a specific disease.     

Malignant fibrous histiocytoma,giant cell type,of the breast mimicking metaplastic carcinoma. A case report

BACKGROUND: We report a case of malignant fibrous histiocytoma, giant cell type (MFHGC), of the breast. A review of the literature failed to reveal cytology-based reports on this entity. The cytologic similarity of breast MFHGC on fine needle aspiration biopsy (FNAB) to other malignant breast neoplasms, including carcinoma with osteoclastlike giant cells, metaplastic carcinoma and breast sarcomas, as well as benign reactive processes, makes the recognition of this tumor challenging. CASE: A 72-year-old woman presented with a 5-month history of an enlarging breast mass. FNAB of the mass showed a hypercellular smear composed of cohesive, branching clusters of spindle cells with ovoid, focally hyperchromatic nuclei and inconspicuous nucleoli. Interspersed osteoclastlike giant cells, some associated with clusters of spindle cells, were uniformly seen throughout the smear. The background was hemorrhagic, with cellular debris and occasional spindle cells and lymphocytes. No ductal epithelial or myoepithelial cells were seen. An incisional biopsy was performed, followed by radical mastectomy. The histologic examination was diagnostic of MFHGC. The diagnosis was supported by immunohistochemical and electron microscopic studies. CONCLUSION: MFHGC, also called primary giant cell tumor of soft tissues, is composed of a mixture of histiocytes, fibroblasts and bland-appearing osteoclastlike giant cells with a multinodular growth pattern. Although MFHGC rarely occurs in the breast and the definitive diagnosis is difficult based on cytology alone, the diagnosis can be considered when a cytologic examination reveals a hypercellular, spindle cell smear with osteoclastlike giant cells in the absence of ductal epithelial or myoepithelial cells.