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Keywords:

  • ThinPrep;
  • cytospin;
  • nongynecologic cytology;
  • fluids;
  • respiratory;
  • exfoliative cytology

Abstract

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

BACKGROUND

There exists limited literature comparing ThinPrep (TP) with conventional cytospins (CS) in nongynecologic specimens.

METHODS

The differences between TP and CS were evaluated for a variety of parameters including cellularity, cytologic morphology, specimen preparation, screening time, laboratory cost effectiveness, cytologist preference, and impact on final diagnosis. Eighty-eight cases including 38 urine, 13 respiratory, and 37 body fluids were prepared simultaneously.

RESULTS

TP and CS demonstrated similar cellular yield in the majority of cases. Cytologists preferred TP in 63 (71.6%) and CS in 6 (6.8%) cases; whereas they indicated no preference in 19 (21.6%) cases. Of 14 abnormal cytologies, a more definitive diagnosis of malignancy was rendered by TP in 6 (42.9%) and by CS in 2 (14.3%) cases. TP demonstrated better nuclear chromatin morphology and more uniform distribution of cells. CS showed larger-sized clusters with better preservation of their architecture compared with smaller-sized clusters and significant shrinkage of cell size in TP.

CONCLUSIONS

TP was preferred over CS in the majority of cases by both cytotechnologists and pathologists. Cellularity, screening time, and specimen preparation were comparable, although the latter was easier to standardize in TP. In abnormal cases, TP was found to be 3 times more helpful than CS in rendering a definitive diagnosis of malignancy. TP, however, was associated with certain artifacts that cytologists must become familiar with when examining such preparations. Although TP was superior to CS in most cases, the application of both methods may be helpful in selected cases in which the TP diagnosis is not conclusive. Finally, TP was found to be more cost effective than CS. Cancer (Cancer Cytopathol) 2006. © 2006 American Cancer Society.

Numerous studies have compared ThinPrep® (TP) (Cytyc Corporation, Marlborough, MA) with conventional preparations in gynecologic cytology1–4 and, more recently, fine-needle aspiration (FNA) specimens.5–8 However, to our knowledge, only limited literature exist contrasting TP to conventional cytospins (CS) in the examination of nongynecologic (non-FNA) specimens.9–19 The purpose of the current study was to evaluate the differences between TP and CS in a variety of parameters including cellularity, specimen preparation, screening time, laboratory cost effectiveness, cytologist preference, and impact on final diagnosis.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Eighty-eight nongynecologic specimens were evaluated, including 38 urine, 13 respiratory, and 37 body cavity fluids. Two fixed cytospins were routinely prepared from respiratory and urine specimens, whereas 2 fixed and 1 air-dried CS were prepared from body cavity fluids. CS were prepared utilizing the Shandon 3 Cytospin® cytocentrifuge (Thermo Electron Corporation, Waltham, MA). The samples were centrifuged at 750 revolutions per minute (rpm) for 5 minutes. Only 1 slide was prepared from all specimen types using the TP, according to the manufacturer's instructions.20 One to two additional concentrated pull smears (CPS) were prepared if initial CS were unsuitable for evaluation due to excessive thickness (ie, highly concentrated or compromised by excessive blood or inflammation). This more diluted CPS allowed for better observation of cellular elements. CPS was prepared by centrifuging the sample at 1700 rpm for 10 minutes and decanting the supernatant fluid. Using a disposable pipette, a drop of the specimen was placed onto a fully frosted glass slide. A plain glass slide was placed on top of the frosted slide and a CPS made. Average times for specimen preparation and screening were calculated from 70 cases. Specimen preparation times did not include computer entry, staining, or coverslipping. Specimens were processed in batch mode. Five cytotechnologists and 1 pathologist (T.M.E.) independently examined paired CS and TP specimens and recorded cellularity and their preferences for each of the cases. Cellularity was semiquantitatively graded as low, moderate, and high (Tables 1, 2). Cellularity and the preferences of the cytotechnologists were determined by tallying the majority response per individual case. Abnormal TP and CS cases were also evaluated by 1 pathologist (T.M.E.) whose observations are recorded in Table 3. Costs of TP and CS (Tables 4, 5) were calculated as follows: 1) specimen preparation labor = hourly preparation technician rate × 0.25 (15 min); 2) screening labor = hourly cytotech rate × 0.083 (5 min); and 3) supply costs = total costs of individual supplies used in processing for each technique.

Table 1. Comparison of Cellularity and Cytologist Preference among All Cases Studied
Specimen typeNo.of casesConventional CS cellularityTP cellularityCytologist preference
LowModerateHighLowModerateHighCSTPSame
  1. CS: cytospins; TP, ThinPrep.

Body fluids3718136221502305
Respiratory132110481166
Urine3816166102533278
Total88364012364846 (6.8%)63 (71.6%)19 (21.6%)
Table 2. Comparison of Cytologist Preference among Cases with Variable Cellularity
Specimen typeNo. of casesBetter cellularityCytologist preference
CSTPCSTPSame
  1. CS: cytospins; TP: ThinPrep.

Body fluids990171
Respiratory532122
Urine13672101
Total2718 (66.7%)9 (33.3%)4 (14.8%)19 (70.4%)4 (14.8%)
Table 3. Abnormal Cases Detected by ThinPrep and Conventional Cytospins
Case no.Specimen typeAge, ySexConventional CSTPPathologist preferenceSignificant change in diagnosisFollow-up
DiagnosisCellularityDiagnosisCellularity
  1. CS: cytospins; TP: ThinPrep; F: female; M: male; LGUC: low-grade urothelial carcinoma; HGUC: high-grade urothelial carcinoma; HPV: human papilloma virus

1Pleural fluid90FSuspicious, favor adenocarcinomaModerateAtypical, favor reactiveModerateCSYesNone
2Pleural fluid70FSmall cell carcinomaModerateFavor small cell carcinomaModerateCSYesHistory of small cell carcinoma. Diff-Quik stain was superior
3Pleural fluid58FFavor small cell carcinomaModerateSmall cell carcinomaModerateTPYesNone
4Pleural fluid69FAdenocarcinoma, rare cellsLowAdenocarcinomaModerateTPNoPrevious history of adenocarcinoma
5Abdominal fluid82FSuspicious for adenocarcinomaLowAdenocarcinomaLowTPYesNone
6Bronchial wash77FAtypical, favor reactiveModerateSuspicious for carcinomaModerateTPYesBiopsy nonsmall cell carcinoma
7Bronchial wash70MAdenocarcinomaModerateAdenocarcinomaHighTPNoBiopsy: nonsmall cell carcinoma
8Bronchial wash65MSuspicious for squamous carcinomaModerateSuspicious for squamous carcinomaLowCSNoBiopsy: squamous carcinoma
9Urine50FAtypical, rule out LGUCLowHGUC vs. polyomaHighTPYesNone
10Urine39FNondiagnostic, no urothelial cellsHighHPV change, nondiagnosticHighTPNoNone
11Urine73MHGUCLowHGUCModerateSameNoBiopsy: HGUC
12Urine60MHGUCLowHGUCModerateSameNoNone
13Urine82MSuspicious for HGUCLowHGUC, therapy effectModerateTPYesNone
14Urine78FDegenerated atypical cellsModerateReactive changesModerateTPYesNone
Table 4. Comparison of Specimen Preparation and Screening Times (in min)
 ThinPrepCytospin (CPT 88108)*Cytospin (CPT 88162)
  • CPS: concentrated pull smears.

  • *

    Includes 2 fixed cytospins.

  • Includes 2 fixed cytospins and 1 air-dried cytospin.

Specimen preparation1513.513.5
Screening time558 (20, if CPS)
Table 5. Comparison of Costs and Potential Revenue per Case (in U.S. Dollars)
 ThinPrep (CPT 88112)Cytospin (CPT 88108)*Cytospin (CPT 88162)
  • CPS: concentrated pull smears.

  • *

    Includes 2 fixed cytospins.

  • Includes 2 fixed cytospins and 1 air-dried cytospin.

  • Figures based on 2005 Indiana Medicare reimbursement (rates are variable from state to state).

Specimen preparation labor3.502.522.52
Screening labor2.502.503.00 (10.00 if CPS)
Supply costs7.306.556.60
Total cost13.3011.5712.12 (34.10 if CPS)
Reimbursement113.6263.7964.96
Revenue (not including pathologist expense)100.3252.2252.84 (30.86 if CPS)

RESULTS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Cytologists (cytotechnologists and pathologists) preferred TP over CS in the majority of cases (Table 1). The cytologist preference for TP was demonstrated in all types of specimens and was shown to be statistically significant (P = .00, Student t-test [SPSS software for Windows, version 11.5; SPSS Inc., Chicago, IL]). Sixty-one of 88 (69.3%) cases had similar cellularity, whereas 27 cases showed variable cellularity (better cellularity by either CS or TP). However, better cellularity by either methodology did not appear to influence the cytologists' preference (Table 2). There was an approximate 5-fold increased preference for TP (19 cases) over CS (4 cases), despite better cellularity demonstrated by CS in twice as many specimens (18 cases vs. 9 cases) (Table 2). Abnormal findings (atypical, suspicious, or malignant diagnoses) were reported by CS or TP in 14 of 88 (15.9%) cases (Table 3). The pathologist reviewer preferred TP over CS in 9 of the abnormal cases, and preferred CS in 3 cases. A more definitive, clinically relevant diagnosis was rendered by TP in 6 abnormal cases, compared with only 2 CS cases (Table 3, Cases 1 and 2). Overall, 5 of 88 (5.7%) cases were diagnosed as atypical/suspicious by TP, but a more definitive diagnosis was rendered in 2 of those cases after examination of their counterpart CS slides. In the latter cases, the combined cytomorphologic features of CS and TP, not differences in cellularity, allowed for better classification of the abnormal cells.

Cytomorphologically, compared with CS, TP demonstrated more uniform distribution of cells with less cellular overlapping and background debris. TP also demonstrated superior nuclear chromatin morphology in urothelial carcinoma (Fig. 1) and adenocarcinoma (Fig. 2), but showed more significant shrinkage of cells. Conversely, CS showed larger-sized clusters with better preservation of their architecture. Cluster formation was retained in TP, but clusters tended to be smaller in size (Fig. 2). In small cell carcinoma, nuclear chromatin details were better observed by TP; however, there was loss of the spindling and the prominent nuclear molding typically observed in CS (Fig. 3).

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Figure 1. High-grade urothelial carcinoma (HGUC) in urine (Case 13). (A) Cytospins showed rare degenerated atypical cells suspicious for HGUC (Papanicolaou stain). (B) ThinPrep demonstrated better preservation of the atypical cells, resulting in a definitive diagnosis of high-grade malignancy (Papanicolaou stain). Original magnification ×400 (A, B).

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thumbnail image

Figure 2. Adenocarcinoma in bronchial washing (Case 7). (A) Cytospins demonstrated three-dimensional, tightly cohesive clusters of large atypical cells, suspicious for carcinoma (Papanicolaou stain). (B) ThinPrep was more cellular and retained cluster formation. However, cell clusters generally were less cohesive on ThinPrep compared with cytospins. Nuclear features of malignancy were better appreciated on ThinPrep (Papanicolaou stain). Original magnification ×400 (A, B).

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thumbnail image

Figure 3. Small cell carcinoma in pleural fluid (Case 2). (A) Cytospins showed prominent nuclear molding and some spindling (DiffQuik stain). (B) ThinPrep demonstrated well-preserved chromatin pattern and nuclear molding. However, nuclear molding and spindling generally were less prominent on ThinPrep compared with cytospins (Papanicolaou stain). Original magnification ×400 (A, B).

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TP and CS specimen preparation times were comparable (Table 4). However, there was significant intertechnician variability noted in specimen processing times and quality of preparations using CS, compared with less variability associated with TP. Screening times were also comparable using TP or CS; however; they were found to be significantly increased (up to a 4-fold increase) when additional CPS were prepared (approximately 20% of CS cases required additional CPS) (Table 4). Although TP is slightly more costly than CS, the potential revenue/profit for the laboratory is approximately doubled with TP (Table 5).

DISCUSSION

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Although our laboratory has utilized the TP methodology for the examination of gynecologic specimens for over 5 years, we have routinely employed CS in the preparation of nongynecologic exfoliative cytology specimens. More recently, however, we experienced high turnover rates in the technical staff in charge of specimen processing. This appeared to produce great variability in the quality of cytospins prepared and, on many occasions, led to the preparation of additional slides. Because this high staff turnover did not appear to affect the quality of gynecologic specimens prepared by TP, we considered implementation of TP in the routine processing of nongynecologic exfoliative specimens. However, in evaluating the literature, we found numerous studies comparing TP with conventional preparations in gynecologic cytology and FNA specimens, but there was limited literature comparing TP with CS in nongynecologic, non-FNA specimens.9–19 Therefore, the current study was undertaken to evaluate the differences between TP and CS for a variety of parameters, including specimen preparation, cellularity, cellular morphology, screening time, laboratory cost effectiveness, cytologist preference, and impact on final diagnosis.

The results of the current study demonstrated that cytotechnologists and pathologists preferred TP over CS in the majority of normal and abnormal cases, despite the better cellularity noted with CS in twice as many cases (Tables 1, 2). Specimen preparation and screening times were comparable, but specimen processing was easier to standardize in TP and appeared to be less operator-dependent (Table 4). Wright and Halford18 and Rana et al.16 also reported that their laboratory staff found TP specimen processing simpler and less labor intensive than CS. Because the amount of cell loss and cellular fixation may be attributed to the skill and experience of preparation staff, the simplicity and uniformity of TP technology appears to reduce this dependence on operator skill significantly, with minimal training required.18

Similar to other previous reports,9, 10, 13, 14, 16–18 the results of the current study also demonstrated that TP is superior or equal to CS for the microscopic evaluation of nongynecologic non-FNA specimens. TP demonstrated more uniform distribution of cells, with superior nuclear chromatin morphology and less cellular overlapping and background debris. However, TP was associated with certain artifacts and cytomorphologic changes that are different from CS and, although subtle, these changes need to be recognized by cytologists. TP was associated with significant shrinkage of cells, resulting in smaller-sized cells compared with CS. Cluster formation in adenocarcinoma was retained in TP, but tended to be smaller in size, compared with larger-sized clusters with better-preserved architecture in CS. In small cell carcinoma, nuclear chromatin details were better observed by TP, but there was loss of the spindling and prominent nuclear molding typically noted in CS. These cytomorphologic differences also have been observed by others.12, 16, 19

We found TP and CS to have comparable diagnostic sensitivity, similar to other studies.9, 10, 14, 17 However, more definitive, clinically relevant diagnoses were rendered in the current study by TP in 6 of 14 abnormal cases, compared with more definitive diagnoses rendered by CS in 2 of those cases (Table 3). Therefore, CS processing may be helpful in selected cases when the TP diagnosis is not conclusive. The latter approach takes advantage of the combined cytomorphologic features of CS and TP in difficult cases, without adding significant burden to the laboratory workload (approximately 6% of our cases). Finally, despite the slight increase in cost, TP is associated with higher reimbursement and profit for the laboratory (Table 5).

REFERENCES

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES