ASCUS, mature metaplastic type. Cytologic diagnosis and follow-up

OBJECTIVE: To study the cytologic criteria for follow-up of mature metaplastic cells within the atypical squamous cells of undetermined significance (ASCUS) category. STUDY DESIGN: Squamous epithelial abnormalities between January 1994 and June 1997 at our institution totaled 2,632 and included squamous carcinoma (1), high grade squamous intraepithelial lesions (278), low grade squamous intraepithelial lesions (875) and ASCUS (1,478). From the ASCUS group, 134 (9.06%) were metaplastic; 89 were selected for review. Criteria for case selection were follow-up with tissue biopsy or at least two Pap smears and no previous epithelial abnormality. Patients ranged from 27 to 70 years of age. Parameters tabulated included number of abnormal cells per slide, their architecture, cell size, shape, cytoplasmic hue and texture, nuclear size and contour, chromatin pattern and nucleoli. Additionally, specimens were reviewed for hormonal status and inflammation. The findings were correlated with follow-up data. RESULTS: Cells generally appeared single or in loose, monolayered sheets of three to seven cells per group. The cells were well demarcated, polygonal or oval and ranged from 11 to 30 microns with cyanophilic or eosinophilic thickened cytoplasm. The round to oval nuclei with slight irregularity showed a minimally increased nuclear/cytoplasmic ratio with stippled chromatin. Upon review, 69 smears were confirmed as ASCUS-M. Follow-up revealed 42 with benign findings, 9 with persistent ASCUS/ASCUS-M and 18 with low grade squamous intraepithelial lesions. CONCLUSION: In mature metaplastic cells with minimal atypia in patients with no previous or concurrent dysplasia, the follow-up details were similar to those described for ASCUS-superficial/immediate squamous cells. These patients could be followed conservatively.     

Papillary carcinoma of the breast. Cytologic study of nine cases.

OBJECTIVE: To study the cytologic findings of papillary breast carcinoma by fine needle aspiration. STUDY DESIGN: The study group consisted of fine needle aspiration (FNA) specimens of breast tumors from nine patients performed during the period 1988-1997. Eight were female, and one was male. The FNA results were compared with the final histologic diagnosis. RESULTS: The tumor sizes were 4-6.5 cm. The aspirations yielded a good amount of bloody material. The smears revealed high cellularity, papillary clusters, isolated low-to-tall columnar cells, mild to moderate atypia, hemorrhagic background, foam and hemosiderin-laden macrophages, calcification, rare mitoses, palisading row of cells and bipolar cytoplasmic eosinophilic granules. The smears were diagnosed as either suspicious or suggestive of papillary carcinoma. The histologic examination revealed invasive papillary carcinoma. CONCLUSION: Papillary carcinoma of the breast can be diagnosed by using a panel of cytologic findings that includes hypercellularity, papillary clusters, hemorrhagic background, palisading rows of tall columnar cells, cellular atypia and calcification. The interesting finding in this study was the presence of eosinophilic bipolar cytoplasmic granules, which has not been reported before.     

Cytologic findings with histologic correlation in 43 cases of mammary intraductal adenocarcinoma diagnosed by aspiration biopsy

OBJECTIVE: To review the cytologic and subsequent histologic findings in intraductal mammary adenocarcinoma (ductal adenocarcinoma in situ) (DCIS) to evaluate the role of aspiration biopsy (AB) in identifying and grading the disease. STUDY DESIGN: AB smears and tissue sections from 43 women with pure DCIS who underwent preoperative AB were reviewed. Smears were assessed for cellularity, cellular arrangement (including dissociation, nuclear size and pleomorphism), and presence of nucleoli and necrosis. RESULTS: Of the 43 cases, 22 were high grade (HG) DCIS, 7 cases were intermediate grade (IG), and 14 cases were low grade (LG). Cytologic findings of HG DCIS was as follows: high cellularity (22/22), clusters of pleomorphic cells with large nuclei and increased nuclear/cytoplasmic ratios (22/22), single cells (20/22), prominent nucleoli (22/22) and necrosis (diffuse in 15/22, focal in 7/22). All LG cases had moderately to highly cellular smears with cohesive, 3-dimensional sheets of uniform, small cells with inconspicuous nucleoli arranged around a central lumen, forming "punched-out" spaces. Single cells were prominent in 2 of 14 cases. IG DCIS showed intermediate features between LG and HG DCIS: 3-dimensional sheets with punched-out spaces, abundant single cells, moderate pleomorphism and focal necrosis. CONCLUSION: HG DCIS is easily identifiable on AB smears; however, distinction from invasive carcinoma may not be possible. The cytologic diagnosis of LG DCIS is difficult, and 50% of our cases were called atypical on AB. Recognition of cohesive cellular arrangements with crowding and punched-out spaces is crucial as single cells and prominent atypia are often lacking.     

Metaplastic carcinomas of the breast—fine needle aspiration (FNA) cytology findings

nogueira m., andré s. and mendonça e. . (1998) Cytopathology 9, 291–300
Metaplastic carcinomas of the breast—fine needle aspiration (FNA) cytology findings
Metaplastic carcinomas of the breast are defined by mesenchymal and/or squamous cell components associated with ductal carcinoma and may raise diagnostic problems in FNA cytology. We reviewed FNA smears of a series of nine cases; seven were compared with histological sections and two with cell-block sections. The cytological pattern was diagnostic of carcinoma in six cases; in two cases a diagnosis of sarcoma/phyllodes tumour was considered, as cells were predominantly spindle-shaped. One case had a pleomorphic adenoma type pattern. The cytological findings suggesting a diagnosis of metaplastic carcinoma include a liquid aspirate, a proteinaceous or chondromyxoid background and a poorly differentiated tumour with multinucleated giant cells, neoplastic or histiocytic. A definite diagnosis requires the presence of both carcinomatous and metaplastic (squamous/mesenchymal) components.     

Immunohistochemical studies with monoclonal antibodies B72.3 and MA5 on histologic and cytologic specimens from benign and malignant breast lesions

Monoclonal antibodies B72.3 and MA5 were tested by the avidin-biotin immunoperoxidase method in histologic sections of 38 benign, 22 precancerous and 22 cancerous breast lesions, as well as in fine needle aspiration (FNA) smears and cell blocks of 25 breast carcinomas. Neither B72.3 nor MA5 was specific for breast cancer cells: both also reacted with cells from benign and precancerous conditions. B72.3 as a "detector" of malignant cells or their precursors was superior to MA5, however: it was not reactive to cells in most benign breast lesions (mammary duct ectasia, fibroadenoma and ductal hyperplasia, with and without atypia). Cancerous cells had heterogeneous immunostaining with B72.3, which may lead to false-negative results in relatively hypocellular FNA samples. FNA samples prepared as both smears and cell blocks provided the most abundant cellular samples and the lowest false-negative immunostaining reaction of cancerous cells with B72.3.     

Comparative cytology of mucocelelike lesion and mucinous carcinoma of the breast in fine needle aspiration

OBJECTIVE: To study the fine needle aspiration cytology (FNAC) features of mucocelelike lesion (MLL) of the breast and to compare them to those of mucinous carcinoma. STUDY DESIGN: The fine needle aspiration (FNA) smears of 7 cases of histologically proven MLL (2 malignant and 5 benign, including 4 associated with atypical ductal hyperplasia) were reviewed and compared to those of 14 mucinous carcinoma cases. RESULTS: In all cases, grossly visible thick, mucoid material was obtained from FNA. The most important features for distinguishing benign MLL from mucinous carcinoma were: (1) scant cellularity; (2) no or rare single, intact tumor cells; (3) tumor cells arranged in cohesive monolayers; and (4) absence of significant nuclear atypia. In contrast, mucinous carcinoma in general showed higher cellularity; abundant single, intact cells; three-dimensional cellular clusters in most cases; and nuclear atypia ranging from mild to severe. CONCLUSION: Mucinous lesions of the breast should be divided into MLL and frank mucinous carcinoma based on FNAC. However, FNAC diagnosis of malignant MLL has yet to be defined. Excisional biopsy is advised for all hypocellular cases for further separation into benign and malignant MLL and to rule out the possibility of hypocellular mucinous carcinoma.     

Benign mucocele-like lesion of the breast: how to differentiate from mucinous carcinoma before surgery.

The aim of the study was to improve the pre-operative diagnosis of mammary mucinous lesions. All mucinous lesions detected by fine needle aspiration (FNA) and confirmed by histological examination were reviewed by cytological findings, mammographic appearances and sonographic findings. Twenty aspirates had corresponding pathology, including 12 mucinous carcinomas, two mucocele-like lesions (MLL) with atypical ductal hyperplasia, three MLL with ductal hyperplasia and three simple MLL. Simple MLL and mucocele-like with ductal hyperplasia showed scant cellularity, no or rare intact single tumour cells, monolayered arrangement and absence of nuclear atypia. In contrast, most mucinous carcinomas showed higher cellularity, more single tumour cells, three-dimensional clusters, and mild to marked nuclear atypia. However, MLL with atypical ductal hyperplasia showed cytological features overlapping with mucinous carcinoma. MLL had a non-specific mammographic appearance and showed a cystic lesion on sonography. Mucinous carcinoma appeared as a solid mass on sonography and as a distinct nodule on mammography. Based on the combination of FNA cytology and image findings, benign MLL can be correctly distinguished from mucinous carcinoma before surgery.     

Cytologic grading and DNA image cytometry of breast carcinoma on fine needle aspiration cytology smears

OBJECTIVE: To correlate the cytologic grade of breast carcinoma with DNA image cytometry (ICM) and nuclear area on fine needle aspiration cytology (FNAC) smears. STUDY DESIGN: In this prospective study, FNAC material from 28 breast carcinomas were studied for cytologic grade and DNA ICM. Breast carcinomas were classified as grade 1-3 (low to high). DNA histograms were classified by the modified Auer method. Degree of hyperploidy (DH), ploidy balance (PB) and nuclear area (NA) were measured on Feulgen-stained smears by a CAS 200 image cytometer. Cytologic grade was correlated with DNA ICM findings and NA. RESULTS: There were 3 cytologic grade 1, 13 grade 2 and 12 grade 3 breast carcinomas. Seven of eight cases of hypertetraploid aneuploidy were grade 3 tumors. All cytologic grade 1 tumors were diploid. There were significant differences in DH, PB and NA in different grades of breast carcinoma (one-way ANOVA). CONCLUSION: DNA image cytometry in combination with cytologic grading might offer additional information for the characterization of breast carcinomas diagnosed by FNAC. These observations are of particular interest with the introduction of preoperative chemotherapy.     

Matricellular CCN6 (WISP3) protein: a tumor suppressor for mammary metaplastic carcinomas

Located at 6q22–23, Ccn6 (WISP3) encodes for a matrix-associated protein of the CCN family, characterized by regulatory, rather than structural, roles in development and cancer. CCN6, the least studied member of the CCN family, shares the conserved multimodular structure of CCN proteins, as well as their tissue and cell-type specific functions. In the breast, CCN6 is a critical regulator of epithelial-to-mesenchymal transitions (EMT) and tumor initiating cells. Studies using human breast cancer tissue samples demonstrated that CCN6 messenger RNA and protein are expressed in normal breast epithelia but reduced or lost in aggressive breast cancer phenotypes, especially inflammatory breast cancer and metaplastic carcinomas. Metaplastic carcinomas are mesenchymal-like triple negative breast carcinomas, enriched for markers of EMT and stemness. RNAseq analyses of the TCGA Breast Cancer cohort show reduced CCN6 expression in approximately 50% of metaplastic carcinomas compared to normal breast. Our group identified frameshift mutations of Ccn6 in a subset of human metaplastic breast carcinoma. Importantly, conditional, mammary epithelial-cell specific ccn6 (wisp3) knockout mice develop invasive high-grade mammary carcinomas that recapitulate human spindle cell metaplastic carcinomas, demonstrating a tumor suppressor function for ccn6. Our studies on CCN6 functions in metaplastic carcinoma highlight the potential of CCN6 as a novel therapeutic approach for this specific type of breast cancer.     

Cytology of nipple discharge in florid gynecomastia

OBJECTIVE: To determine the cytomorphologic spectrum of nipple discharge in florid gynecomastia. STUDY DESIGN: During a 22-year period (July 1979-June 2001), nipple discharge from nine males with breast lesions were examined. Smears from four of these cases with histologically documented gynecomastia were reviewed along with the tissue sections. RESULTS: In the three patients with florid gynecomastia the smears were cellular, with numerous benign ductal cells and papillary fragments along with foam cells and inflammatory cells. Epithelial atypia was mild in two cases and moderate in one. One of the three cases had an associated breast lump that showed features of florid gynecomastia on fine needle aspiration cytology. The biopsy from this case showed cystic hyperplasia of the breast similar to that in women with an intraductal papilloma. One case of simple gynecomastia on histology showed two fragments of benign ductal cells with occasional apocrine and foam cells. CONCLUSION: Nipple discharge in florid gynecomastia may pose problems in identification as the cellularity and atypia may lead to a misdiagnosis of carcinoma.     

Characteristic cytological features of histological grade one (G1) breast carcinomas in fine needle aspirates

Objective:  To analyse the spectrum of nuclear features as well as dissociation pattern found in fine needle aspirates (FNAC) from histological grade 1 breast carcinomas and evaluate the critical cytological features of these lesions.
Material and methods:  The material consisted of FNAC smears from 494 histologically confirmed grade 1 breast carcinomas. All smears were revaluated for cell dissociation pattern, nuclear size, cell uniformity, nucleoli, nuclear margin and chromatin pattern. All features were compared with the histological subtype and cytological grading.
Results:  73.9% of the cases were cytological grade 1, 24.3% were grade 2 and 1.8% were grade 3. The majority of the cases had a cell dissociation pattern showing both a population of single carcinoma cells and cell clusters (65.9%). Practically all tumours had a granular chromatin pattern (94.7%) and a slightly irregular nuclear margin with folds and grooves (94%) irrespective of histological subtype and cytological grading. Nucleoli were mostly indistinct or small (74%), whereas 24.3% were noticeable and 1.7% abnormal. Practically all cases revealed some degree of pleomorphism with 74.3% showing mild and 22.4% a distinct pleomorphism. A small subgroup of IDC was classified as monomorphic (3.3%). Almost all tumours had nuclear sizes in the range of 2–4 × RBC (96.9%).
Conclusion:  Not all histological grade 1 carcinomas are cytological grade 1. About 25% were grade 2, and a small subpopulation reached grade 3. The typical/average findings in FNAC from grade 1 breast carcinomas were a population of both groups and single cells showing mild pleomorphism, granular chromatin, slightly irregular nuclear margin, indistinct nucleolus and nuclear size 2–4 × RBC.     

Mixed apocrine-medullary carcinoma of the breast. Report of a case with fine needle aspiration cytology

The case of an unusual variant of breast carcinoma arising in an 80-year-old woman is presented. Fine needle aspiration (FNA) cytology of this carcinoma revealed sheets of cells showing apocrine differentiation and significant cellular atypia mixed with lymphocytes and plasma cells. At mastectomy, the neoplasm was found to have features of both apocrine carcinoma and medullary carcinoma, with a prominent lymphocytic infiltrate. This case underlines the difficulty in distinguishing between malignant apocrine cells and apocrine metaplastic cells by FNA cytology. The presence of an inflammatory component, as seen in this case, may compound such difficulties.     

Endocervical and metaplastic cells: comparison of endocervical and metaplastic cell number in Papanicolaou smears with and without squamous intraepithelial lesion

OBJECTIVE: To compare, with a retrospective study, endocervical and metaplastic cell number to identify the cytology of squamous intraepithelial lesion (SIL) of the cervix. STUDY DESIGN: Cytology files from March 2000 to March 2003 were reevaluated, and those with SIL were identified. RESULTS: In 8,743 cervicovaginal smears were found 70 (0.8%) SIL smears (39 low grade, 31 high grade) and 140 randomly selected smears without squamous or glandular abnormalities that were not atrophic or unsatisfactory. Endocervical and metaplastic cells counted in these smears and then classified into 5 groups were compared with each other. CONCLUSION: Women with smears containing endocervical cells are not at greater risk for SIL than those with smears lacking these cells. Women with smears containing metaplastic cells are more likely to have SIL than those without metaplastic cells. In addition, high grade lesions are more likely in smears containing more metaplastic cells.     

Aspiration cytology of fibrosarcomatous variant of dermatofibrosarcoma protuberans with osteoclastlike giant cells in the chest wall: a case report

BACKGROUND: A case of fibrosarcomatous variant of dermatofibrosarcoma protuberans (FS-DFSP) with osteoclastlike giant cells involved the dermis and subcutaneous tissue of the chest wall. This case was misdiagnosed as primary breast tumor clinically and had cytologic features similar to those of the metaplastic breast carcinoma (MRBC). CASE: A 53-year-old female presented with a nodular breast mass enlarging slowly over a long period of time and growing rapidly for about 3 months. The aspirates showed high cellularity with both individually scattered and fascicular arrays of spindle cells. A few multinucleated giant cells without nuclear atypia were intermixed with dissociated spindle cells. There was no epithelial component in the smear. Cytologic evaluation suggested the possibility of a low grade spindle cell sarcoma as well as MBC. Subsequently, the patient underwent modified radical mastectomy, and the diagnosis of FS-DFSP was made. CONCLUSION: Distinguishing FS-DFSP with osteoclastlike giant cells from other spindle cell tumors of the breast, especially MBC showing predominantly spindle cell components, may pose significant challenges to the pathologist. However, clinical and radiologic findings and a meticulous search for other components raised the possibility of FS-DFSP on aspiration cytology.     

Metaplastic carcinoma of the breast in an HIV-positive patient: a case report

BACKGROUND: Metaplastic carcinoma of the breast is a rare neoplasm that causes diagnostic difficulty on fine needle aspiration smears. Breast carcinoma in HIV-infected patients occurs at a relatively early age, with increased bilateral disease, unusual histology, and early metastatic spread with a poor outcome. CASE: A case of metaplastic carcinoma of the breast arose in a 36-year-old woman who was seropositive for HIV. In the absence of a sarcomatous component and presence of obvious ductal differentiation on aspirates, a diagnosis of high grade infiltrating duct carcinoma, not otherwise specified, was made on fine needle aspiration cytology (FNAC). CONCLUSION: This case underlines the limitations of FNAC in the diagnosis of metaplastic carcinoma of the breast. It also shows that it is imperative to maintain a high index of suspicion for rare pathologies in immunocompromised patients.     

Signet ring cells in fine needle aspiration cytology of breast carcinomas: review of the cytological findings in ten cases identified by histology

Objective:  To establish whether the presence of signet ring cells (SRCs) in histology sections of breast carcinoma cases was reflected by their presence in fine needle aspiration cytology (FNAC) smears, correlating to the histological type of breast carcinoma.
Methods:  We reviewed the FNAC findings of ten cases that had been diagnosed as primary breast carcinoma with SRCs on histological sections between 1998 and 2007. Slides and histological sections were obtained from the archives of Ege University Hospital.
Results:  FNA smears were reviewed for the following cytomorphological features: background, cellularity, architecture, nuclear pleomorphism and the presence of SRCs. The background was bloody in eight cases, necrotic in one, and clean in one. There was no mucinous material in any of the cases. Cellularity was prominent in five cases (hypercellular), moderate in three (cellular) and low in two (hypocellular). Loosely cohesive groups of tumour cells of varying size were observed in all cases. A plasmacytoid appearance to some of the tumour cells was seen in all cases and discohesive tumour cells were present in eight. Nuclear pleomorphism was high in six cases and moderate in four. SRCs were observed in seven of the ten cases. Two of these seven cases also had a tubular pattern and one had tumour giant cells.
Conclusions:  FNAC should be evaluated carefully regarding the presence of SRCs when cells with a plasmacytoid appearance are observed in either hyper- or hypocellular smears. The presence of single SRCs in FNACs with hypercellularity, high nuclear grade and tubular formation or tumour giant cells may be a clue in favour of ductal carcinoma. The presence of single SRCs in FNACs with hypocellularity and mild to moderate nuclear grade may be suggestive of lobular carcinoma. However, larger studies would be needed to establish the predictive value of the presence of SRCs on FNAC.     

Macrophage-rich reaction in lymph nodes as a mimic of metastatic renal cell carcinoma on fine needle aspiration. A case report

BACKGROUND: Renal cell carcinomas have a high metastatic potential. Many of them are occult at initial presentation and mimic a primary neoplasm of the metastatic site. However, not all lymph node enlargements in a patient with a history of renal cell carcinoma are due to metastasis. Foamy macrophages can mimic metastatic renal cell carcinoma cells. CASE: A 60-year-old male with a known diagnosis of renal cell carcinoma of clear cell type developed enlarged neck nodes 44 months after the diagnosis. These were aspirated to yield cystic fluid that, on smears, showed numerous clear cells with low nuclear grade. Immunohistochemical stains revealed these cells to be foamy macrophages (CD68 immunoreactive) and not metastatic renal cell carcinoma, as had been suspected on initial examination of Diff-Quik and Papanicolaou-stained smears. CONCLUSION: Immunohistochemistry is a valuable adjunct in avoiding a false diagnosis of metastatic carcinoma in macrophage-rich nodal reactions in patients with a history of renal cell carcinoma.     

Neuroendocrine ductal carcinoma in situ of the breast: cytological features in 32 cases

T. Kawasaki, S. Nakamura, G. Sakamoto, T. Kondo, H. Tsunoda‐Shimizu, Y. Ishii, T. Nakazawa, K. Mochizuki, T. Yamane, M. Inoue, S. Inoue and R. Katoh
Neuroendocrine ductal carcinoma in situ of the breast: cytological features in 32 cases Objective: The purpose of this study was to clarify the cytological features of neuroendocrine ductal carcinoma in situ (NE‐DCIS) of the breast. Methods: We analysed the cytopathological findings in 22 fine needle aspiration (FNA) smears and 17 nipple discharge smears obtained from 32 Japanese patients with NE‐DCIS. Results: The background of the FNA smears was clear (59%), mucoid (23%), haemorrhagic (14%) or necrotic (5%). Most of the FNA smears (95%) showed high cellularity. Characteristically, NE‐DCIS cells were loosely arranged in three‐dimensional solid clusters or singly dispersed. Well‐developed vascular cores with or without malignant cells were occasionally recognized. The tumour cells were polygonal or spindle‐shaped with a fine granular, abundant cytoplasm. Nuclei with finely granular chromatin were round or oval and often eccentrically located (plasmacytoid appearance). Mitotic figures were infrequent. Nuclear grade was estimated to be low in 86%. Most nipple discharge smears had fairly low cellularity with poorly preserved cell clusters in a markedly haemorrhagic background, although two (12%) were extremely cellular with cytological characteristics similar to those of the FNA smears. Pre‐operative cytological malignant diagnoses were made in 42% of FNA smears and 0% of nipple discharge smears. Immunohistochemistry for neuroendocrine markers (chromogranin A and synaptophysin) confirmed the neuroendocrine nature of this tumour in adequate cytological specimens. Conclusions: NE‐DCIS has distinctive cytological features and can therefore be diagnosed as a neuroendocrine tumour in most FNAs and some nipple discharge smears by cytological examination employing immunohistochemical techniques. We emphasize that a breast lesion with these features may be in situ and not invasive, and also that there is a risk of under‐diagnosis.     

Analysis of cervical smears obtained within three years of the diagnosis of invasive cervical cancer

The cytologic histories of 376 women presenting with invasive carcinoma of the cervix were analyzed. In total, 202 (53.7%) of these women had had 355 smears taken during the three years preceding presentation. All 320 smears with an original cytologic diagnosis of less than cancer were reviewed. The original cytologic diagnosis was low in 95 (30.6%) of 310 adequate smears. Originally, 96 (30.9%) of the adequate smears were evaluated as negative; at review, only 55 (17.5%) of the adequate smears were evaluated as negative. Comparing the review diagnoses to the 355 total smears, the rates of negative smears were 13.5% (42 of 310) for squamous-cell carcinoma, 30.0% (12 of 40) for adenocarcinoma and 20.0% (1 of 5) for adenosquamous carcinoma (P less than .05). The cellular composition of the smear was significantly related to the cytologic detection of abnormalities: endocervical cylindrical and/or metaplastic cells were seen in only 45.5% of smears diagnosed as negative, but in 84.4% and 97.8% of smears diagnosed as atypia and cervical intraepithelial neoplasia, respectively P less than .00001). Smears without endocervical cells should be considered inadequate and should be repeated.     

Fine needle aspiration cytology of radiation-induced changes in nonneoplastic breast lesions. Possible pitfalls in cytodiagnosis

The range of radiation-induced changes in fine needle aspiration (FNA) smears of the breast is described. In 41 of more than 800 patients who underwent breast-conserving treatment, a palpable breast lesion developed, and FNA was performed. In six cases, a recurrent carcinoma was present. In the remaining cases, three patterns of nonneoplastic lesions could be discerned: epithelial atypia (14 cases), fat necrosis (10 cases) and poorly cellular smears without epithelial atypia or fat necrosis (13 cases). It is important to be familiar with the patterns of radiation-induced epithelial atypia, since such atypia may lead to a misdiagnosis of recurrent carcinoma. These atypical cells may show impressive anisocytosis and anisonucleosis; however, the nuclear/cytoplasmic ratio remains normal and an admixture of bipolar cells is present. Cell dissociation and necrotic cell debris, as often seen in breast cancer smears, were never encountered in FNA smears from radiated nonneoplastic breasts.