Cytological criteria of endometrial lesions with emphasis on stromal and epithelial cell clusters: result of 8 years of experience with intrauterine sampling

Objective:  There are a number of unresolved issues in endometrial cytology. They include the significance of nuclear atypia for the diagnosis of grade1 adenocarcinoma (G1AC) and atypical endometrial hyperplasia (AEH), cytological criteria of endometrial hyperplasia without atypia, and recognition of stromal cell cluster (SC) and its distinction from epithelial cell cluster (EC).
Methods:  We examined nuclear atypia, SC and EC in typical cases of five categories: normal endometrium (NEM), simple endometrial hyperplasia without atypia (SEH), complex endometrial hyperplasia without atypia (CEH), G1AC and grade2 adenocarcinoma (G2AC). We classified EC into four types: simple EC (SPEC), large regular EC (LREC), large irregular EC (LIEC) and small irregular EC (SIEC). Based on the results, we developed criteria of endometrial cytology and have evaluated 13 639 cases over 8 years.
Results:  Nuclear atypia was significantly more frequent in G2AC than in any of the other four categories ( P  <   0.001). SC was significantly more frequent in NEM and SEH than in the other three categories ( P  <   0.001). G1AC and G2AC showed significantly higher frequency of LIEC than the other three categories ( P  <   0.001). CEH exhibited significantly higher frequency of LREC than the four categories ( P  <   0.001). The sensitivity and the specificity was 88.8% and 99.0% respectively.
Conclusions:  We could diagnose G1AC, G2AC and CEH with high accuracy using the established criteria mainly based on SC and EC. We think that the criteria may facilitate an effective screening and an objective interpretation of endometrial samples.     

Atypical glandular cells in cervical smears: histological correlation and a suggested plan of management based on age of the patient in a low-resource setting

Objectives:  To perform an audit of all smears reported as atypical glandular cells (AGC) using the Bethesda system (TBS) 2001.
Methods:  A total of 18 376 cervical smears were screened from January 2005 to June 2007, of which 65 cases were reported as AGC. Follow-up histology was available in 31 cases (47.7%), in whom a detailed cytological/histological correlation was carried out.
Results:  AGC constituted 0.35% of all Pap smears. Follow-up histology was normal or benign in 20 cases, whereas a squamous or glandular abnormality was seen in 11 cases. Squamous abnormalities included one case each of cervical intraepithelial neoplasia (CIN)1, CIN2 and CIN3 and five cases of squamous cell carcinoma. All glandular epithelial abnormalities were endometrial in origin and included two endometrial adenocarcinomas and one uterine serous carcinoma. Neither in situ nor invasive adenocarcinoma of the endocervix was observed. Review of smears and reclassification as AGC, not otherwise specified and favour neoplasia revealed a higher proportion of abnormality in the latter group, reaffirming the utility of subtyping. The median age of women with AGC was 41 years. The outcome was analysed with respect to the median age. In women aged equal or more than 40 years, AGC reflected a high-grade squamous or glandular epithelial abnormality in 50% of cases compared with none in those less than 40 years old ( P  = 0.010).
Conclusion:  The age of the woman as well as the subtype of atypical glandular cells influences outcome and hence must be taken into consideration while formulating an acceptable management strategy in these women in a low-resource setting.     

New diagnostic reporting format for endometrial cytology based on cytoarchitectural criteria

Objective:  The aim of this study was to develop a new reporting format for endometrial cytology that would standardize the diagnostic criteria and the terminology used for reporting.
Methods:  In previous studies, cytoarchitectural criteria were found to be useful for the cytological assessment of endometrial lesions. To apply these criteria, an appropriate cytological specimen is imperative. In this article, the requirements of an adequate endometrial cytological specimen for the new diagnostic criteria are first discussed. Then, the diagnostic criteria, standardized on a combination of conventional and cytoarchitectural criteria, are presented. Third, terminology that could be used, not only for reporting the histopathological diagnosis, but also for providing better guidance for the gynaecologist to determine further clinical action, is introduced. The proposed reporting format was investigated using endometrial cytology of 58 cases that were cytologically underestimated or overestimated compared to the histopathological diagnosis made on the subsequent endometrial biopsy or surgical specimens.
Results:  Of the 58 cases, 12 were reassessed as being unsatisfactory for evaluation. Among the remaining 46 cases, 25 of the 27 cases, which had been underestimated and subsequently diagnosed as having endometrial carcinoma or a precursor stage on histopathological examination,were reassessed as recommended for endometrial biopsy. On the other hand, 19 cases overestimated by cytology were all reassessed as not requiring biopsy.
Conclusions:  The reporting format for endometrial cytology proposed in this article may improve diagnostic accuracy and reduce the number of patients managed inappropriately.     

Cytological aspects of uterine cervical adenocarcinoma, adenosquamous carcinoma and combined adenocarcinoma-squamous carcinoma: appraisal of diagnostic criteria for in situ versus invasive lesions

Cytological aspects of uterine cervical adenocarcinoma, adenosquamous carcinoma and combined adenocarcinoma-squamous carcinoma: appraisal of diagnostic criteria for in situ versus invasive lesions
This paper reports the cytological findings based on air-dried smears in a retrospective series of 143 cases of endocervical adenocarcinoma, combined adenocarcinoma-squamous carcinoma and adenosquamous carcinoma drawn from the files of the BC Cancer Registry. Cervical cytology smears were available before biopsy in 131 patients, but in 18 cases the cytology showed no abnormality. Malignant changes or high-grade atypia of glandular and/or squamous cells (defined as moderate or severe dyskaryosis) were detected in 103 cases. In 46 cases, only a high-grade squamous abnormality was detected. Low-grade glandular and/or squamous lesions were detected in nine cases and one showed atypical endometrial-type glands. The cervical smears of 64 cases were reviewed in detail to determine the important cytomorphological criteria of in situ and invasive adenocarcinoma in air-dried smears, the technique used for preparing PAP smears in British Columbia. Endocervical cells were absent in four cases. Numerous (>10) groups of glandular cells were present in 51 cases. Important clues to the diagnosis of adenocarcinoma included crowding of nuclei, stratification of nuclei, loss of polarity, syncytial balls and papillary groups of glandular cells, nuclear enlargement, nuclear pleomorphism, and the presence of free-lying atypical glandular cells. Nuclear hyperchromatism, chromatin pattern, nuclear borders, nuclear membranes, and numbers and morphology of nucleoli were not helpful criteria in our material. Criteria enabling reliable distinction between in situ and invasive adenocarcinoma and/or mixed adenocarcinoma-squamous carcinoma could not be established.     

Decrease in numbers of glandular cell groups in post-LLETZ liquid-based cytology preparations

Objective:  Large loop excision of the transformation zone (LLETZ) has become standard of care in the management of cervical squamous neoplasia and with cone biopsy glandular intraepithelial neoplasia. Controversy remains about the long-term effects of this traumatic procedure. The aim of this study was to count and compare the number of endocervical glandular cell groups in pre- and post-LLETZ cervical preparations using liquid-based cytology to establish a cyto-morphological correlate of destruction of the transformation zone.
Methods:  The cytology/histology correlation audit records of the Cytopathology Department of St Luke's Hospital in 2003 and early 2004 were used to select patients with a cytological diagnosis of high grade dyskaryosis followed by LLETZ. Only those cases with post-LLETZ cytological follow-up were selected. Cases using conventional smears were excluded. One hundred and twenty slides (60 pairs of slides) in total were retrieved. The cases underwent review and all groups of >3 glandular cells in each slide were counted by AM while blinded as to whether smears were pre- or post-LLETZ. Medians were compared using a Mann–Whitney U -test.
Results:  The median number of groups of endocervical glandular cells of the pre-treatment group was 5.5 and of the post-treatment group was 2.0. There were significantly fewer endocervical glandular cell groups in the post-LLETZ population ( P  = 0.03).
Conclusions:  The number of endocervical glandular groups in cervical cytological preparations decreases significantly following LLETZ procedure. This suggests that cytological follow-up may not be as useful in glandular neoplasia cases. Few or absent glandular cell groups in post-LLETZ preparations may have implications for adequacy assessment.     

Extramedullary plasmacytoma, a report of five cases diagnosed by FNAC

Objective:  To review cytological findings and diagnostic challenges in the use of fine needle aspiration in the diagnosis of extramedullary plasmacytoma.
Methods:  Five cases of extramedullary plasmacytoma that were initially diagnosed on fine needle aspiration cytology over a period of two years in Sir Ganga Ram Hospital were reviewed.
Results:  The cytological findings were similar in all five cases. The smears were cellular and composed of plasmacytoid cells arranged singly and in clusters, with varying pleomorphism, bi- and multinucleation and mitotic figures. Presence of anaplasia, increased plasmablasts, numerous naked nuclei and unusual location of the tumour were some of the challenges faced during the cytological evaluation.
Conclusions:  Extramedullary plasmacytoma may occur either as an initial presentation or as a secondary involvement by multiple myeloma. Fine needle aspiration is a reliable technique for its rapid diagnosis.     

A review of post-trachelectomy isthmic and vaginal smear cytology

Currently in the UK cervical cancer has a peak incidence in women aged 35-39. Fertility-conserving surgical treatment by radical trachelectomy is established in the management of early disease. This study aimed at establishing the value of cytology in follow-up after trachelectomy. The cytological features of isthmic-vaginal smears post-trachelectomy for cervical cancer are presented together with a discussion of relevant clinical issues. One hundred and ninety seven smears from 32 women were reviewed. Two of the 32 patients developed pelvic recurrences. In both cases recurrence was detected cytologically long before development of a clinical or radiological abnormality. There is, however, a potential for overcall due to the presence of endometrial cells. These were present in large numbers and varying configurations in 58% of smears and led to a false positive report of malignancy in 2% of smears. The rate of referral for a cytologist opinion was significantly higher in smears containing endometrial cells (26%) than those without (13%). While all smears contained squamous cells, 41% contained squamous cells only and it is proposed that such smears should be reported as unsatisfactory in the first 2 years after surgery and negative thereafter, although the absence of glandular cells should be recorded. When an abnormality is reported, smear review and multidisciplinary discussion may avoid unnecessary investigations.     

Cytology of benign multicystic peritoneal mesothelioma in peritoneal washings

Objective:  To describe the cytological aspect of peritoneal washings in benign multicystic peritoneal mesothelioma (BMPM).
Methods:  Three peritoneal washing specimens stained by standard cytological and histological procedures and analysed by light microscopy.
Results:  The specimens showed an abundance of monomorphous mesothelial cells devoid of atypia or mitoses. The mesothelial cells were calretinin positive. They also showed numerous squamous metaplastic cells arranged in flat sheets or isolated cells. The background contained some inflammatory cells.
Conclusion:  The combination of cytology of the peritoneal washing, histology (cell block and surgical specimen) and clinical history allow differentiation of BMPM from other cystic lesions (cystic lymphangioma and malignant mesothelioma).     

Fine needle aspiration cytology of the testis as the first-line diagnostic modality in azoospermia: a comparative study of cytology and histology

Objectives:  Male factors are responsible for about half of all infertility cases. Until recently, testicular biopsy was the standard method to ascertain the aetiology of azoospermia. Fine needle aspiration cytology has gained increasing popularity as a simple and minimally invasive procedure that can help in assessing testicular function accurately. This study was aimed at addressing the question whether testicular fine needle aspiration (FNA) may be used as a first-line diagnostic modality in azoospermia and to assess its usefulness in the diagnostic protocol.
Methods:  The FNA was performed in 78 consecutive azoospermic patients. To obviate sampling errors both testes were aspirated, except when contraindicated. Routine haematoxylin and eosin as well as Romanowsky staining was performed on the smears.
Results:  The smears were categorized on cytological examination into normal spermatogenesis in 35 (50%) patients, Sertoli cells only syndrome in 22 (31.4%) and maturation arrest at the spermatocyte/spermatid level was seen in 13 (18.4%) patients. There were eight (10.2%) cases with scant smears where cytological diagnosis could not be made. A good correlation between cytological smears and histological sections was found in 54 of 58 testes (93.1%) in which histopathological confirmation was available.
Conclusions:  Testicular FNA may be utilized as a first-line investigative modality in patients with azoospermia, provided the procedure is performed and interpreted by experts.     

Mastopathic fibroadenoma of the breast: a pitfall of aspiration cytology

OBJECTIVE: To assess the correlation between cytological diagnoses and histological subtypes of fibroadenoma (FA) and to clarify the cytological features of a specific group of FA displaying variable features similar to fibrocystic disease (mastopathic type, MFA), and to evaluate the significance of this subtype in cytological diagnosis. METHODS: A review of 141 cases of histologically proven FA was performed. We re-classified them into four subtypes according to Kinoshita's criteria [Jpn J Breast Cancer6 (1991) 377] and further selected 92 cases for which both fine needle aspiration (FNA) smears and histological specimens were available. Among them, 18 cases of MFA and their cytological smears were selected for the present study. RESULTS: There was significant correlation between MFA and cytological diagnosis of 'indeterminate' or 'suspicious for malignancy' (P < 0.01). Although no false-positive diagnosis was experienced in our series, 56% of the MFAs (10/18) had cytological diagnoses of indeterminate or were included in the category 'suspicious for malignancy'. Smears from MFA revealed high cellularity (9/18 smears had more than 10 epithelial clusters each composed of more than 50 cells), presence of cellular discohesiveness (13/18, 72.2%), but only mild nuclear atypia (5/18, 27.8%). Anisonucleosis was present in fewer than half the cases and no apparent condensed chromatin was identified. CONCLUSION: We highlight the significance of subclassification of MFA in aspiration cytology of breast. MFA had a significantly higher chance of falling into the 'suspicious for malignancy' or 'indeterminate' diagnostic category in aspiration cytology. It might be a diagnostic challenge for cytopathologist to identify this subtype of FA in FNA smears.     

The role of cervical cytology and colposcopy in detecting cervical glandular neoplasia

Objective:  To determine the role of cervical cytology and colposcopy in the management of endocervical neoplasia.
Setting:  Colposcopy unit and cytology laboratory in a teaching hospital.
Sample:  Group 1 included 184 smears showing endocervical glandular neoplasia from 129 patients and group 2 included 101 patients with histology showing endocervical abnormalities in a 6-year period (1993–1998). Follow-up of 6–11 years to 2004 was available.
Methods:  Group 1 were identified from the cytology computer records. Group 2 were identified from histology records on the cytology database and a record of histology cases kept for audit purposes. The clinical records were examined retrospectively.
Results:  The positive predictive value (PPV) of abnormal endocervical cells in smears was 81.1% for significant glandular/squamous [cervical glandular intraepithelial neoplasia (CGIN)/cervical intraepithelial neoplasia grade2 (CIN2 or worse)] lesions. The PPV of colposcopy was 93.5% for significant glandular/squamous lesions of the cervix. The postcolposcopy probability of a significant lesion when colposcopy was normal was 87.5%. The sensitivity of colposcopy in detecting endocervical lesions was 9.8%. The sensitivity of cervical smears in detecting a significant endocervical abnormality (CGIN or worse) was 66.3%. The false negative rate for cytology of endocervical glandular lesions was 4.0%.
Conclusions:  Endocervical glandular neoplasia detected on cytology is predictive of significant cervical pathology even when colposcopy is normal, which supports excisional biopsy in the primary assessment of these smears. The high concomitant squamous abnormality rate justifies the use of colposcopy to direct biopsies from the ectocervix. Cervical cytology is the only current screening method for cervical glandular abnormalities but sensitivity is poor.     

Cytodiagnosis of endometrial malignant mixed mesodermal tumor

The accuracy of endometrial aspiration smears obtained with the Isaacs cell sampler in the diagnosis of malignant mixed mesodermal tumors (MMMT) was compared to the results obtained with routine cervical and vaginal smears in five cases of MMMT found in a series of 220 endometrial aspirations. Cervical and vaginal smears previously taken on these patients were positive for adenocarcinoma or MMMT in two cases and suspicious for adenocarcinoma in the remaining three cases. Endometrial aspirates were positive for MMMT in three cases and positive for adenocarcinoma or MMMT in two cases. The endometrial aspiration smears contained a variety of cells: malignant glandular, squamous, spindly stromal, undifferentiated, osteoid and tumor giant cells; chondrocytes and free psammoma bodies were also observed. These cases indicated that endometrial aspiration can accurately detect the heterologous cellular elements found in MMMT and is an effective technique in its diagnosis.     

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.     

Deep-seated rectal/anal basaloid carcinoma: useful immunocytochemistry in rare squamous cell carcinoma variants

Objectives:  To report the cytological aspects of ano-rectal basaloid carcinoma (BC) variant in endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) conventional and liquid-based cytology (LBC), in a series of 10 cases of deep-seated squamous cell carcinomas (SCC), and to discuss the diagnostic difficulties in interpreting the morphology and immunocytochemical findings.
Methods:  Ten cases of EUS-FNA smears and LBC specimens of deep-seated pelvic masses were retrospectively collected from January 2001 to November 2006.
Results:  Ten EUS-FNA specimen cases were SCC, eight corresponding to usual SCC and two to BC-variant. Of these two cases, only one was correctly diagnosed by EUS-FNA specimen, whereas in the second case, the initial cytological diagnosis was poorly differentiated adenocarcinoma and the final diagnosis of basaloid carcinoma variant was established on surgical resection. Immunocytochemistry (ICC) using CK7, CK20 and CK34βe12 on FNA specimens confirmed the diagnosis retrospectively.
Conclusion:  The diagnosis of basaloid variant of SCC in a rectal location can be very difficult, both on account of the uncommon location and because of the low specificity of morphological aspects on EUS-FNA smears. The immunocytochemical technique, including a limited spectrum of keratins (CK7, CK20, CK34βe12, and p63) is necessary to avoid this diagnostic pitfall.     

Clinico-cytological study of uterine papillary serous carcinoma

OBJECTIVE: The aim of this study was to determine whether or not we could distinguish uterine papillary serous carcinoma (UPSC) from other types of endometrial cancer by cytology. METHODS: We examined the cytological findings of the endometrium from five cases with UPSC and compared them with 10 cases with endometrioid adenocarcinoma, grade 1 (G1). A morphometric analysis was performed. Cytological samples from the cervix and ascites of the patients with UPSC were also reviewed. RESULTS: All five patients had FIGO stage III and IV tumours. Three patients died of the disease and two are still alive with disease. The tumour cells of UPSC tended to be shed in papillary clusters with a tumour diathesis. Psammoma bodies were seen only in UPSC. The frequency of irregular-shaped nuclei, membrane thickness and eccentric nuclei in UPSC was higher than in G1. The chromatin pattern was coarsely granular, and both anisonucleosis and bare nuclei were prominent in UPSC. Cytomorphometrically, the maximum diameter of the nuclei in UPSC was significantly greater than that in G1. The nucleoli were also more often seen in UPSC than in G1. The findings of the nuclei and nucleoli in the cervical and peritoneal fluid cytology closely resembled those in endometrial smears. The features of the cervical smears and peritoneal fluid cytology were different from those of endometrial cytology regarding clear background and small clusters of cells. CONCLUSION: As the endometrial cytology findings accurately suggested the histological diagnosis of UPSC, the diagnosis of UPSC was confirmed in this study by endometrial cytology. The cytological diagnosis of UPSC should be based on the findings of tumour diathesis, psammoma bodies and papillary clusters composed of tumour cells with enlarged nuclei and numerous nucleoli.     

Evaluation of p16INK4a in cervical lesion of premenopausal and postmenopausal women

Pap smears of postmenopausal women are often misdiagnosed because of the difficulty in distinguishing atrophic epithelial cells groups only by morphological criteria. In this study we investigated the diagnostic application of immunocytochemical staining of p16INK4a on conventional Pap smear. A total of 137 cervical specimens were enrolled in this study, of which 77 and 60 cervical smears were taken from premenopausal and postmenopausal women, respectively. Two cervical smears were taken simultaneously in 68 women, one for conventional cytology and the other for immunostaining. Additional 69 cervical smears were taken from the archive, decolorized and then used for immunostaining. In premenopausal women 1 out of 14 (7.1%) with negative cytology, 7 out of 24 (29.2%) with low grade squamous intra-epithelial lesion (LSIL), all 35 (100%) with high grade squamous intraepithelial lesion (HSIL) and all 4 (100%) with squamous cell carcinoma (confirmed by histopathology) had positive staining to p16INK4a. In postmenopausal women p16INK4a positivity was observed in 4 out of 7 (57.1%) cases of LSIL, 12 out of 14 (85.7%) cases of HSIL and all 4 out of 5 (80%) different cases of carcinoma (1 cervical adenosquamous carcinoma and 3 cervical squamous cell carcinoma in situ confirmed by histopathology), but none of 34 smears with normal cytology. Twenty smears with normal cytology chosen for the negative control in this study were from the group of postmenopausal women and were as expected negative for p16INK4a immunostaining. In the group of postmenopausal women, 16 out of 60 (26.7%) cases the cytological diagnosis was established on the basis of pl6lNK4a immunostaining as being HSIL. From our preliminary study on a limited number of samples, we can however conclude that pl6INK4a immunostaining is a very useful tool for cytological diagnosis enabling to distinguish HSIL from normal, reactive or inflammatory changes.     

Endocervical glandular cell abnormalities in conventional cervical smears: evaluation of the performance of cytomorphological criteria and HPV testing in predicting neoplasia

Objective:  To analyse the correlation between cytomorphological criteria in smears with atypical glandular cells (AGC) or adenocarcinoma in situ (AIS) and human papillomavirus (HPV) reflex test results with different neoplastic histological diagnoses, particularly to distinguish between glandular and squamous neoplasia.
Methods:  A series of 155 women with glandular abnormalities in their conventional cervical smears was included: 106 with AGC, 35 with AGC associated with high-grade squamous intraepithelial lesion (HSIL) and 14 with AIS. Two reviewers evaluated 35 cytomorphological criteria and hybrid capture II (HCII) was performed in all cases. Colposcopy was carried out in all cases and biopsy in 126/155. For statistical purposes, predictive values and odds ratio (OR) were calculated, followed by chi-square automatic interaction detection.
Results:  Histology detected 56 cases of squamous and 17 of glandular intraepithelial or invasive neoplasia. Predictive values of the papillary groups and feathering criteria for glandular neoplasia were, respectively, 80.0% and 73.3%. Feathering was the criterion with the highest OR for distinguishing glandular from squamous neoplasia and also for distinguishing between glandular and non-neoplastic diagnosis. Rosettes and pseudostratified strips did not perform as well. Multivariant Classification and Regression Trees analysis identified feathering as the best criterion for distinguishing between glandular, squamous and non-neoplastic diagnoses regardless of HPV status.
Conclusions:  Feathering was the best criterion for predicting glandular neoplasia.     

Endometrial hyperplasia with berrylike squamous metaplasia and pilomatrixomalike shadow cells. Report of an intriguing cytohistologic case

BACKGROUND: The usefulness of endometrial cytology as a diagnostic method in asymptomatic women, especially in postmenopause, in the interpretation of composite pictures characterized by borderline features between atypical hyperplasia and well-differentiated adenocarcinoma, especially if associated metaplastic features are present, is somewhat controversial. CASE: An asymptomatic, 50-year-old, postmenopausal woman underwent a Pap smear and endometrial cytology for routine screening, disclosing three-dimensional, sometimes pseudopapillary groupings of hyperplastic endometrial glandular cells with focal atypia in direct continuity with large, squamoid cells of the keratinizing type and shadow cells. Histologic examination of endometrial tissue was advised, and two subsequent endometrial biopsies and hysteroscopic ablation were performed. The borderline character of the lesion (complex atypical hyperplasia vs. well-differentiated adenocarcinoma) with concomitant squamous metaplasia and pilomatrixomalike shadow cells prevented diagnostic agreement between several pathologists. CONCLUSION: Diagnostic cytology with direct endometrial sampling represents a valuable diagnostic screening tool for the differential diagnosis between normal and pathologic endometrium, a mucosal picture that deserves a subsequent (histologic) diagnostic procedure. In a few cases, as in the one presented above, even histologic examination, especially of so-called borderline lesions, reveals squamous or other types of metaplasia that can lead to interobserver discrepancies.