Diagnostic Utility and Accuracy of Scrape Cytology in Evaluation of Neoplastic Lesions.

BACKGROUND: Frozen section, intraoperative fine needle aspiration cytology (FNAC) and imprint cytology have been used traditionally by the surgical pathology laboratories for rapid intraoperative diagnosis of tumors. Scrape cytology is a modification of imprint cytology that involves lightly scraping or brushing cells from freshly cut surface of the surgically removed tumor specimens. The present study was carried out to evaluate the utility of scrape cytology in diagnostic evaluation of tumors.
MATERIAL AND METHODS: A prospective study was carried out at a tertiary care teaching hospital in Central India. A total of 50 consecutively received specimens in the Department of Pathology and Laboratory Medicine with clinical or radiological suspicion of neoplasia were included in the study. Scrape smears were prepared from freshly cut surface of tumor specimens received unfixed or in 10% formalin.
RESULTS: Overall, the scrape cytology diagnosis was concordant with final histopathological diagnosis in 48 out of 50 cases with a diagnostic accuracy of 96%. The sensitivity was 90.9% (CI-58.72% to 99.77%) and specificity was 97.4%(CI-86.52% to 99.94%). Positive predictive value and negative predictive value were 90.91% and 97.44%, respectively.
CONCLUSION: Scrape cytology is a cost-effective and reasonably accurate cytodiagnostic technique for rapid tumor diagnosis. Scrape cytology can be a useful supplementary tool to frozen section, and may be applied for rapid diagnosis where frozen section technique is not available. The material and knowledge obtained from scrape cytology of routinely received histopathological specimens can be utilized as a teaching material and may help unveil diagnostic cytopathological features of infrequent cytologically encountered lesions. Copyright:

INTRODUCTION

Intraoperative evaluation of tumors is crucial in optimizing the surgical management to be undertaken, and at times obviating unnecessary radical surgical procedure. Frozen section, intraoperative fine needle aspiration cytology (FNAC) and imprint cytology have been traditionally used by the surgical pathology laboratories for rapid intraoperative diagnosis of tumors. Scrape cytology is a modification of imprint cytology that involves lightly scraping or brushing cells from freshly cut surface the surgically removed specimens. This may be useful in cases that are not readily amenable to preoperative FNAC like intra-abdominal lesions in vascular proximity, or conditions where FNA is contraindicated or inconclusive as to establish the benign or malignant nature of the lesion due to inadequate specimen acquisition, poor fixation during smear preparation or contamination with blood.

Scrape cytology is simple and cost-effective technique with emerging diagnostic utility. Several studies have been done in past to evaluate the role of imprint cytology and FNA in intraoperative diagnosis of tumors, especially ovarian neoplasms.[123] However, there are only few studies that have been performed on use of scrape cytology in a wide range of neoplastic lesions. The present study was carried out to evaluate the utility of scrape cytology in diagnostic evaluation tumors.

MATERIAL AND METHOD

A prospective study was carried out at a tertiary care teaching hospital in Central India. Ethics approval was obtained from Institutional Ethics Committee. A total of 50 consecutively received specimens in the Department of Pathology and Laboratory Medicine with clinical or radiological suspicion of neoplasia were included in the study. The specimens received unfixed for intraoperative diagnosis and those sent in 10% neutral buffered formalin were included. Specimens were examined and gross findings were recorded. The specimens were then divided into 2 halves with a sharp knife and freshly cut surface of the tumor was immediately scraped with the edge of a glass slide or a surgical blade. The obtained semi-fluid material was spread over glass slides, and 4 to 5 smears were prepared by smearing the material with the help of another glass slide. Out of these, 2 to 3 smears were fixed immediately in absolute alcohol and stained by Rapid Hematoxylin and Eosin technique, whereas 1-2 smears were air dried and stained with Giemsa. Additional stains including special stains were performed wherever required.

Rapid Hematoxylin and Eosin staining was performed in the following manner: i) Fixation in absolute alcohol (99.9%) for 1 to 2 minutes; ii) Washing the smear under running tap water; iii) Staining the smear with Hematoxylin for one minute; iv) Washing the smear under running tap water; v) Staining the smear with eosin stain by dipping 1- 2 times vi). 1-2 dips in Acetone I followed by 1-2 dips in Acetone II; vii) 1-2 dips in Xylene I followed by 1-2 dips in Xylene II; viii) Mounting in DPX.

Diagnosis and tumor grading was done based on cellularity, cellular architecture, pleomorphism, Nucleus to Cytoplasmic ratio, mitotic activity, and necrosis. Category-based analysis was done to differentiate between benign or malignant lesions, and a definitive diagnosis was made wherever possible. Tumor tissue was grossed as per protocols and representative sections were submitted for histopathological processing. Histopathology was considered gold standard for final diagnosis. All statistical analysis was performed by using SPSS21.0 version software for Windows.

RESULTS

A total of 50 cases of surgically resected specimens were included in the study. These included excisional biopsies and tumor resections. Out of total cases, 33 (66%) were females and 17 (34%) were males. The age of patients ranged from 1.5 years to 67 years. Out of total cases, there were 39 (78%) benign lesions and 11 (22%) malignant lesions. A wide range of specimens were received, which included lesions of head and neck, thyroid, breast, gastrointestinal system, liver, kidneys, female genital tract, lymph nodes, soft tissue lesions and skin. Table 1 enlists the lesion categories with cytological and histopathological diagnosis.

Table 1

Categories of lesions with cytopathological and histopathological diagnosis

Specimen (n=50)	Cytopathological diagnosis	Histopathological diagnosis
Head and Neck (n=10)	Well differentiated squamous cell carcinoma (n=1)Suspicious of metastatic deposits of Poorly differentiated carcinoma (n=1)Benign spindle cell lesion (n=1)Pleomorphic adenoma (n=1)Benign spindle cell lesion (n=1)Benign spindle cell lesion/fibrohistiocytc lesion (n=1)Carotid body tumor (n=1)Schwannoma (n=1)Myxoid mesenchymal neoplasm of uncertain malignant potential (n=1)Descriptive (n=1)	Well differentiated squamous cell carcinomaMetastatic deposits of Poorly differentiated carcinomaAngiofibromaPleomorphic adenomaSchwannomaFibromatosis ParagangliomaSchwannomaMyxoid Angiofibroma Ameloblastoma
Lymph node (n=1)	Hodgkin’s Lymphoma (n=1)	Hodgkin’s Lymphoma
Thyroid (n=1)	Papillary Thyroid Carcinoma (n=1)	Papillary Thyroid Carcinoma
Breast (n=7)	Infiltrating ductal carcinoma with axillary Lymph node metastasis (n=1)Fibroadenoma (n=5)Gynecomastia (n=1)	Infiltrating ductal carcinoma NOS with axillary Lymph node metastasisFibroadenoma (n=5)Gynecomastia
Gastrointestinal Tract (n=3)	Necrotizing lymphadenitis (n=1)Adenocarcinoma (n=1)Gastro Intestinal Stromal tumor (n=1)	Intestinal tuberculosisModerately differentiated adenocarcinomaGastro Intestinal Stromal tumor
Liver (n=1)	Negative for malignancy (n=1)	Negative for malignancy
Kidney (n=2)	Wilms tumor with heterologous elements (n=1)Renal cell carcinoma (n=1)	Wilms tumor with rhabdomyomatous differentiationClear cell renal cell carcinoma [Grade-2]
Female Genital Tract (n=16)	Uterine Leiomyoma (n=3)Ovarian Endometriotic Cyst (n=2)Ovarian Mature cystic teratoma (n=1)Ovarian Mature cystic teratoma (n=3)Serous cystadenoma (n=4)Mucinous cystadenoma (n=2)Serous cystadenocarcinoma (n=1)	Uterine Leiomyoma (n=3)Ovarian Endometriotic Cyst (n=2)Immature teratomaOvarian Mature cystic teratoma (n=3)Serous cystadenoma (n=4)Mucinous cystadenoma (n=2)Serous cystadenocarcinoma
Soft tissue tumors (n=6)	Pleomorphic sarcoma withBony resection margins free (n=1)Lipoma (n=5)	Undifferentiated pleomorphic sarcoma with Bony resection margins freeLipoma (n=5)
Skin and adenexal lesions (n=3)	Lobules of sebaceous cells, squames, no atypia may be consistent with Nevus sebaceous (1)Atypical squamous cells seen (1)Benign adenexal tumor (1)	Nevus Sebaceous Well differentiated squamous cell carcinomaBasaloid neoplasm possibly eccrine poroma

Scrape smears prepared were adequate for opinion in 100% of the cases studied. Staining duration was 4-5 minutes and mean time of obtaining the cytodiagnosis was fifteen minutes. A definitive cytological diagnosis was offered in 47 (94%) cases, whereas 3 (6%) cases were offered a categorical report as to benign or malignant/suspicious nature of lesion. The latter included a case of well-differentiated squamous cell carcinoma which showed singly dispersed squamous epithelial cells showing mild to moderate atypia; a case of ameloblastoma and a case of nevus sebaceous which showed lobules of sebaceous glands and anucleate squames [Figure 1].

Figure 1

Scrape smears in a case of ameloblastoma showing palisaded sheets and strands of ameloblast like epithelial cells with loosely arranged reticulum-like cells in background (a, H and E × 100 and b, H and E × 200); Histopathology of the same case (c, H and E × 400); Scrape smears of nevus sebaceous showing mature and few immature lobules of sebaceous glands and anucleate squames (d, H and E × 200)

Overall, the scrape cytology diagnosis was concordant with final histopathological diagnosis in 48 out of 50 (96%) cases [Table 2]. Of the two discordant cases, one case of ovarian teratoma was reported as mature cystic teratoma on scrape cytology; however, extensive histopathological sampling revealed an immature neuroepithelial element and was finally reported as immature teratoma (false negative). The other was a case of parapharyngeal mass in a 15-year-old boy, which was reported on cytology as myxoid spindle cell lesion of uncertain malignant potential owing to nuclear pleomorphism, whereas histology showed a myxoid angiofibroma with degenerative atypia (false positive) [Figure 2].

Table 2

Cytohistopathological correlation of benign and malignant lesions

Lesion category	Number of cases	Number of cases with Cytohistopathological concordance	Number of cases with Cytohistopathological disconcordance
Benign	39	38	1
Malignant	11	10	1
Total	50	48	2

Figure 2

Scrape smears in a case of teratoma showing squamous epithelial cells, hair shafts and glial elements (a and b, H and E ×200); Histopathology of the same case showing immature elements (c, H and E ×200); Scrape smears from a case of myxoid angiofibroma, showing spindle cells showing mild to moderate atypia in a myxoid background. No atypical mitosis or necrosis was seen (d, H and E ×200)

We reported an uncommon case of Wilms tumor with rhabdomyomatous differentiation in a 1.5-year-old girl. The cellular scrape smears showed mesenchymal component, abortive glomeruli, and tubules with frequent rhabdomyoblasts having elongated eosinophilic cytoplasm with prominent cross-striations and centrally located spindle-shaped vesicular nuclei [Figure 3]. Scrape smears from a case of gastrointestinal stromal tumor (GIST) showed cellular smears with clusters and fascicles of spindle cells showing mild to moderate pleomorphism, having fine nuclear chromatin and indistinct nucleoli with scant cytoplasm [Figure 4].

Figure 3

Wilms tumor with rhabdomyomatous differentiation with cellular scrape smears showing mesenchymal component, abortive glomeruli and tubules (a-d, H and E ×200); Rhabdomyoblasts having markedly elongated eosinophilic cytoplasm with prominent cross-striations and centrally located spindle shaped vesicular nuclei (e, Papanicolaou ×200); Histopathology of the same case (f, H and E ×400)

Figure 4

Scrape smears from paraganglioma showing dispersed monomorphic population of cells with round nuclei, moderate eosinophilic granular cytoplasm (a, H and E ×100); Pleomorphic sarcoma showing dispersed spindle cells with hyperchromatic, highly pleomorphic nuclei. Few multinucleate cells, mitotic figures also seen (b, H and E ×200); Gastrointestinal stromal tumor showing cellular smears with clusters and fascicles of spindle cells showing mild to moderate pleomorphism, having fine nuclear chromatin and indistinct nucleoli with scant cytoplasm (c, H and E ×200)

Overall, the diagnostic accuracy of scrape cytology to differentiate benign and malignant neoplasms was found to be 96%. The sensitivity was 90.9% (CI-58.72% to 99.77%) and specificity was 97.4% (CI-86.52% to 99.94%). Positive predictive value and negative predictive value was 90.91% and 97.44%, respectively.

DISCUSSION

Methods to quantify the clinical aggressiveness, extent, and spread of a given neoplasm are of diagnostic and prognostic significance. Surgically removed specimens are routinely diagnosed on histopathology. Intraoperative FNA, imprint, cytology and frozen sections are useful for rapid diagnostic evaluation of tumors. Usefulness of intraoperative FNA and imprint cytology has been reported in several previous studies, particularly ovarian tumors.[456] However, only few studies have been performed on utility of scrape cytology in diagnosis of a wide range of neoplastic lesions.

Diagnostic accuracy of scrape cytology in this study was found to be 96%. Kolte et al.[7] studied the role of scrape cytology in 75 surgically resected specimens and reported comparable results with a diagnostic accuracy of 97%. The results of this study were similar to results of a study performed by Mahore et al.[8] on 169 specimens, who reported the diagnostic accuracy rate of scrape cytology to be 93.5%. Another study performed by Shidham et al.[9] on 446 specimens received for intraoperative consultation reported diagnostic accuracy of scrape cytology to be comparable to frozen section.

A study was performed by Khuroo MS et al.[10] to evaluate the role of scrape cytology in the diagnosis of thyroid lesions and comparison to FNAC results, which showed an overall diagnostic accuracy of scrape cytology to be 89.1% with sensitivity and specificity of 83.87% and 100% respectively. The authors found excellent results for diagnosing benign thyroid lesions, with all lesions having a benign diagnosis on histopathology, diagnosed as benign on scrape cytology. Malignant lesions also were diagnosed satisfactorily with a true positive rate of 83.3%. In another study performed on 128 patients to evaluate utility of scrape cytology in vertebral lesions, the overall diagnostic accuracy of scrape cytology was reported to be 97.58%.[11] Bakshi et al.[12] reported the utility of scrape cytology in diagnosis of ocular neoplastic lesions like sebaceous gland carcinoma and squamous cell carcinoma.

Although most studies on utility of scrape cytology have used unfixed specimens received for intraoperative consultation, in this study we found that scrape preparations of formalin-fixed specimens done as a routine at the grossing station can help in learning and teaching cytological features of tumors and can help improve interpretation skills of FNAC. In the present study, we described a case of Wilms tumor with rhabdomyomatous differentiation, for which, cytology has been sparsely reported.[13] A case of ameloblastoma was seen, showing palisaded sheets of ameloblast-like epithelial cells with loosely arranged spindled and stellate reticulum-like cells in background. Similar cytomorphological findings in ameloblastoma have been previously reported in few of the previous studies.[1415]

Angiofibroma of soft tissue is a histologically distinctive benign mesenchymal neoplasm of unknown cellular origin.[16] To the best of our knowledge, cytology of myxoid angiofibroma has not been previously described. Mild to moderate degenerative atypia may result in suspicion, however, a note of caution should be made of atypical mitosis or necrotic foci while interpretation of cytology.

In this study, we also described a case of nevus sebaceous. The cytosmears showed cellular smears comprising of many lobules of mature and few immature sebaceous cells along with squamous epithelial cells. These cytomorphological findings, in correlation with clinical findings, may aid in correct diagnosis. Scrape cytology may help study the cytomorphology of cutaneous adenexal neoplasms, for which literature is limited as these lesions are infrequently subjected to FNAC.[1718]

One of the drawbacks of scrape cytology over frozen section is that it does not provide information on the depth of infiltration of tumor. Similar problem was faced in a case of well-differentiated squamous cell carcinoma of skin, whereby scrape smears showed squamous cells with mild to moderate atypia, whereby a cytodiagnosis of squamous cell carcinoma could not be offered. In one of the studies comparing frozen section over scrape cytology in ovarian neoplasms, the diagnostic accuracy of frozen section and scrape cytology was found to be 100% and 96% respectively.[19] However, in the present study, frozen section was not performed. Obtaining scrape smears from multiple slices and variegated areas of a tumor can yield more representative elements and better results.

In the present study, we found that scrape cytology is a reliable, easy, cost-effective and reasonably accurate cytodiagnostic technique for rapid diagnosis of tumors. Scrape cytology can be a useful adjunct to frozen section for tumor diagnosis. It can be applied for rapid diagnosis where frozen section technique is not available. This method is less time-consuming, doesn't require special instrument or setup and may provide the surgeon and pathologist a quick insight in to the type of lesion in question. Scraping yields cellular smears, without sacrificing of the tissue needed for histology diagnosis or other immunocytochemical determinations. Furthermore, scrape cytology material may also be used for ancillary tests. The material and knowledge obtained from scrape cytology of routinely received histopathological specimens can be utilized as a teaching material and may help unveil diagnostic cytopathological features of infrequent cytologically encountered lesions.

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Conflicts of interest

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