Sahel Medical Journal

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 24  |  Issue : 3  |  Page : 111--116

Study on concordance of specific cytological diagnosis with histology in a teaching hospital


Akinfenwa Taoheed Atanda1, Ramat Olayinka Faro-Tella2,  
1 Department of Pathology, Bayero University; Department of Pathology, Aminu Kano Teaching Hospital, Kano, Nigeria
2 Department of Pathology, Aminu Kano Teaching Hospital, Kano, Nigeria

Correspondence Address:
Dr. Ramat Olayinka Faro-Tella
Department of Pathology, Aminu Kano Teaching Hospital, PMB 3452, Kano
Nigeria

Abstract

Background: Fine-needle aspiration cytology (FNAC), a cheap screening technique, has helped reduce the diagnostic turnaround time of palpable swellings from different anatomical sites. In light of the technique increasingly being used as a definitive diagnostic tool, it is thus important to evaluate its accuracy in making specific diagnosis beyond just being a screening tool. Objective: To determine the concordance rate between cytological and histological diagnosis Materials and Methods: Cytology and corresponding histology reports for lesions from patients with maxillofacial, lymph node, and abdominal swellings, where both were available, were compared for the concordance of specific cytological diagnosis with final histological diagnosis. Results: In the 10-year (2006–2015) studied, there were 177 complete cases in which specific diagnoses were made on cytology; of these, 135 (75.3%) were in concordance with histological diagnoses. Concordance for intra-abdominal, maxillofacial, and lymph node aspirates was 90.2%, 85.5%, and 62.9%, respectively. Cytological concordance of specific diagnosis for benign and malignant lesions was 70.7% and 79.5%, respectively. Concordances for lymphomas, carcinomas, and sarcomas were 84.1%, 68.2%, and 66.7%, respectively. The specific cytologic diagnosis was enhanced by preaspirate ultrasound scan while the absence of immunocytochemistry hampered accuracy in specific diagnosis of nodal non-Hodgkin's and Hodgkin's lymphoma (66.7% and 42.9%), respectively. Conclusion: This study concludes that FNAC is a simple technique with fairly reliable utility in proffering specific diagnosis on suitable lesions. However, in developing countries where repertoire of antibodies for immunocytochemistry may be limited, the accuracy will be improved by good clinical history and preaspirate ultrasound where necessary.



How to cite this article:
Atanda AT, Faro-Tella RO. Study on concordance of specific cytological diagnosis with histology in a teaching hospital.Sahel Med J 2021;24:111-116


How to cite this URL:
Atanda AT, Faro-Tella RO. Study on concordance of specific cytological diagnosis with histology in a teaching hospital. Sahel Med J [serial online] 2021 [cited 2021 Nov 28 ];24:111-116
Available from: https://www.smjonline.org/text.asp?2021/24/3/111/329521


Full Text



 Introduction



Historically, earlier application of fine-needle aspiration cytology (FNAC) is traced back to 1000 AD when therapeutic needle puncture of the thyroid was carried out by an Arabian physician, Albucasis.[1] From then, till the present, the technique has metamorphosed from being barely acceptable to being currently relied upon in clinical practice. In Nigeria, the earliest record of its application in the clinical evaluation of patients dates back to 1986 when Bhursnamath et al.[2] published their findings on fine-needle aspiration performed on 220 patients with cytohistologic correlation in 71 of the cases at the Ahmadu Bello University Teaching Hospital, Zaria, Northwestern Nigeria. A review of the technique in the country by Malami and Ochicha[3] shows high degree of acceptability of the technique in Nigeria.

FNAC is a veritable tool in preliminary screening of benign from malignant swellings. The procedure has gained much usage by clinicians because of the relatively shorter turnaround time compared with conventional histology. However, with specialization in the area of cytopathology, it is increasingly becoming the norm to extend the usefulness of this procedure from its traditional role in screening to making specific diagnosis. It thus becomes important to evaluate its accuracy in making specific diagnosis.

 Materials and Methods



Study design

This is a retrospective study of FNAC and final histology reports over a 10 year period (2015-2016) in a teaching hospital.

Inclusion criteria

Patients with maxillofacial, lymph node, and abdominal swellings.

Exclusion criteria

Unsatisfactory smears and where no specific diagnosis was rendered on cytology were excluded from the study.

Aspiration and tissue biopsy procedure

The lesions were aspirated using size 25G needles and obtained material smeared on grease free glass slides and stained with May Grunwald Giemsa and Papanicolaou stains. Smears with clinical suspicion of tuberculosis were treated with Ziehl–Neelsen stain for acid fast bacilli.

Tissues biopsied for histology were placed in 10% neutral buffered formalin solution and subjected to routine paraffin embedding and H and E staining technique. The slides were assigned similar accession numbers as with corresponding fine needle aspirates from the same patients. Cases with equivocal features on H and E were further subjected to immunohistochemistry. All patients' clinical information was kept confidential.

Data analysis

Ensuing data were managed using SPSS version 20 (IBM, Armonk, NY, United states of America). Categorical variables are presented as numbers and percentages. Tables of frequencies were generated. The cytopathology and histopathology diagnosis were compared for concordance rate.

Ethical approval for this study (NHREC/21/08/2008/AKTH/EC/1330) was provided by the Ethical Committee Aminu Kano Teaching Hospital, Kano, Nigeria on 22nd January 2015.

 Results



In the 10 years studied, there were 177 cases in which specific diagnoses were made on cytology; of these, 135 (75.3%) were in concordance with histologic diagnoses. Concordance for intra-abdominal, maxillofacial, and lymph node aspirates was 90.2%, 85.5%, and 62.9%, respectively. Concordances for lymphomas, carcinomas, and sarcomas were 84.1% (53/63), 68.2% (15/22), and 66.7% (4/6), respectively.

Maxillofacial aspirates

[Table 1] these included 55 cases, 47 (85.5%) of which were accurately diagnosed by cytology. Hundred percentage concordances were reported for pleomorphic adenoma, tuberculosis, lymphoepithelial cyst, lipoma, Burkitt's lymphoma, and poorly differentiated carcinoma. [Figure 1] shows a case of tuberculosis and pleomorphic adenoma. Two of 3 (67%) sarcomas and 50% of the adenoid cystic carcinoma (ACC) were correctly diagnosed. Ameloblastoma, dentigerous cyst, odontogenic keratocyst, and leiomyoma, even though were reported as benign lesions did not agree with histologic diagnosis. The malignant ex-pleomorphic adenoma was also inaccurately diagnosed as a squamous cell carcinoma.{Table 1}{Figure 1}

Lymph node aspirates

[Table 2] there were 81 diagnoses from lymph nodes during the study. Localized lymphadenopathy involving one or two groups was seen in 68 (83.9%) cases while generalized lymphadenopathy was seen in the remaining 13 (16.1%) patients. Most of the aspirates (29 of 68; 42.7%) were from cervical lymph nodes, while the infra-auricular nodes were the least frequently affected (1.2%).{Table 2}

Benign lesions accounted for 42 (51.9%) of the 81 cases, with diagnosis-based concordance for reactive lymphadenitis and tuberculosis being 66.7% and 60%, respectively. Three cases of reactive lymphadenitis were wrongly concluded as malignant, and one of them further suggested lymphoma. Similarly, a case of tuberculous adenitis was also erroneously suspicious of lymphoma. Concordance was highest for the diagnosis of metastatic carcinoma (72.2%) and lowest for a case of metastatic leiomyosarcoma (0%). Despite the high concordance for metastatic carcinoma, a misdiagnosis of reactive and chronic suppurative lymphadenitis was observed. Concordance for the diagnosis of non-Hodgkin's lymphoma (NHL) was higher than that for Hodgkin's lymphoma (HL), 66.7% versus 42.9%. Two cases of NHL and three cases of HL were diagnosed as reactive lymphadenitis while two cases of HL were reported as tuberculous adenitis. Furthermore, two cases of HL were reported as NHL and metastatic carcinoma on cytology.

[Figure 2] shows a case of metastatic carcinoma and HL.{Figure 2}

Intra-abdominal aspirates

[Table 3] forty-one cases of intra-abdominal lesions were aspirated, 37 (90.2%) of which were given accurate specific diagnosis on cytology. Burkitt's lymphoma, similar to what was found for jaw tumors, showed 100% concordance; 100% concordance was also reported for the two sarcomas. Concordance for nephroblastoma was 83% while that for neuroblastoma was 78%.{Table 3}

 Discussion



Diagnostic concordance for intra-abdominal, maxillofacial, and lymph node aspirates was 90.2%, 85.5%, and 62.9%, respectively.

The high diagnostic concordance noted for pleomorphic adenoma in this study is similar to that reported in a study from Netherlands.[4] As highlighted by Gahine et al.[5] identification rests mainly on the identification of three-dimensional cohesive clusters of ductal cells, background of singly lying plasmacytoid myoepithelial cells, and dense fibrillary brightly metachromatic stroma with partially obscured entrapped myoepithelial cells.

Other maxillofacial lesions with 100% diagnosis-specific concordance (lipoma and lymphoepithelial cyst) are also characterized by highly specific features. Other workers have also reported a similarly high diagnostic concordance for the lipomatous lesions.[6] The high accuracy for lymphoepithelial cysts in our study reflects HIV-positive status, bilaterality, and presence of epithelial cells in a background of lymphoid cells and histiocytes. Similar features were found in the study by Elliot and Oertel.[7] The greater challenge faced, however, was in the diagnosis of odontogenic cysts which, even though may show occasional squamous cells, they cannot be differentiated from other cysts such as dentigerous cysts, or when the odontogenic cyst is inflammed, as noted by Ramzy et al.[8]

Diagnosis-specific concordance of cytology for malignant lesions of the maxillofacial region was 91% (29 of 32 cases). One of the two cases of ACC was misdiagnosed as an undifferentiated carcinoma because the characteristic small cells with hyperchromatic-molded nuclei, scanty cytoplasm, and background hyaline globules, as noted in the medical literature,[9] were absent. The malignant ex-pleomorphic adenoma was missed due to inadequate sampling. The missed maxillofacial sarcomatous lesion was a case of osteosarcoma comprised atypical spindle cells which showed no characteristic osteoid, most likely because these cannot pass through the needle bore.

Burkitt's lymphoma is the most common childhood malignancy in Nigeria,[10] thus cytopathologists have had ample experience with their diagnosis. Smears mostly show sheets of intermediate-sized lymphoid cells with multiple nucleoli, thin rim of vacuolated bluish cytoplasm, frequent mitotic figures, lymphoglandular bodies, and variable numbers of background tingible body macrophages.[11] Experience with this diagnostic entity may explain why irrespective of the site (head and neck and intra-abdominal)-specific diagnosis was accurate in 100% of the cases.

The specific cytologic diagnosis was interchanged in misdiagnosed cases of nephroblastoma and neuroblastoma. This is due to shared cytological features mostly composed of rosettes; absence of one or two of nephroblastoma suggesting features including blastemal, epithelial, and stromal components and absence of fibrillary background in neuroblastoma. However, in the cases where the specific diagnosis was concordant, there was preaspirate radiological diagnosis as guide to localizing the lesions. Our cytohistologic concordance of 83% for nephroblastoma is lower than the 100% reported by Alam et al.,[12] while that for neuroblastoma (78%) is closer to the 87.5% reported by others.[13]

Cytohistologic concordance for specific diagnosis of sarcomas in pediatric age group in our series was 100% and 50% (two of four cases) for adult cases. This reflects the greater diversity of diagnostic possibilities in the latter age group. Similarly, the disparity in specific diagnosis in the two groups reported by Kilpatrick et al.[14] with 92% in children and 52% in adults. Immunocytochemical application to conventional cytology appears to have become the panacea to overcoming the limitation of FNAC in subclassifying the soft-tissue sarcomas.[15]

Only 18.1% (4 of 22) of tuberculous smears were acid-fast positive on Zeihl–Neelsen (ZN) stain. This falls within the range of 5%–77.1% described in previous literature.[16],[17] In spite of the low sensitivity of ZN stain, highly suggestive histories, clinical features, presence of multinucleated giant cells or epithelioid histiocytes, and background necrotic debris were useful enough to enable a specific cytologic diagnosis of tuberculosis in 72.7% (16 of 22) of cases, similar to the 75.4% reported in an Indian study.[18] Cases specifically diagnosed with chronic suppurative inflammation had numerous neutrophilic infiltrates with scanty epithelioid histiocytes on histology. In the absence of caseation or in lymph nodes infected by atypical mycobacteria with poorly formed granulomatous reaction, cytological presentation as a reactive hyperplasia is not uncommon as reported by Mohammed et al.[19] and Akinde et al.[20] A review of the false-positive case which was suspicious of lymphoma showed areas of necrosis and epithelioid histiocytes sufficient to preclude a diagnosis of lymphoma.

Aspirates from lymph nodes were the most common and showed a concordance of 62.9% for specific diagnosis. The specific diagnosis of NHL on cytology was more accurate than for HL. Concordance of 66.7% for the specific diagnosis of NHL found in our study falls in the range (62%–75%) reported by others.[21],[22] Das et al.[23] reported 92% concordance for specific diagnosis of HL which is much higher than 42% recorded in the present study. Nevertheless, our figure still falls within the range of 30%–92% documented in other literatures.[24],[25],[26] This further emphasizes the controversies surrounding the use of FNAC in the definitive diagnosis of HL.[27]

The false-negative cases of lymphoma in this study are remarkable. Progressive transformation of lymph nodes in lymphomas, absence of architectural features of effacement, and capsular invasion are contributory factors to false negatives in the cytological diagnosis of lymphomas as noted by Kocjan.[28] The misinterpretation of small lymphocytic lymphoma may stem from the fact that minimal cytomorphological atypia of low-grade lymphomas is barely perceptible on cytology, and the admixture of reactive polymorphous small lymphocytes and histiocytes with neoplastic cells further compounds the morphological picture.[22]

The other case of NHL reported as reactive lymphadenitis was a lymphocyte-rich diffuse large B-cell lymphoma (DLBCL). The presence of mature-appearing lymphocytes and histiocytes constituted a distraction from the neoplastic lymphocytes. On the other hand, the presence of only the requisite reactive background inflammatory cells and absence of Reed–Sternberg (RS) cells, as encountered in two of the three false-negative cases of HL, was responsible for the misdiagnoses as reactive lymphadenitis. A similar observation was also made by Hehn et al.[29] in a study with the same theme as the index study. Conversely, reactive immunoblasts simulating RS cells explain the reason for false-positive diagnosis of HL in reactive lymphadenitis. Finally, granulomas may constitute part of the reactive component of HL explaining the two cases reported as granulomatous inflammation.

Two cases of HL diagnosed as NHL and carcinomatous metastasis were of the lymphocyte-depleted and mixed cellularity subtypes, respectively. The relatively large number of RS cells was probably perceived as atypical large lymphoid cells in the former and atypical epithelial cells in the latter. Anaplastic large cell lymphoma is particularly notorious for mimicking HL on cytology.[30] Frequently, classical RS cells are known mimics of binucleated cells of metastatic nasopharyngeal carcinoma in cervical lymph nodes,[31] explaining the latter case diagnosed as metastatic carcinoma. A detailed clinical history and utilization of immunophenotypical studies are necessary for resolving such diagnostic dilemmas.

Even though screening concordance for metastatic carcinomas in most studies has been near perfect, the cytohistologic concordance for specific diagnosis of metastatic lesions in lymph nodes has ranged from 76% to 100%.[32],[33] Sampling error from a partially effaced lymph node and a focus of tumor diathesis are probable reasons for misdiagnosis of reactive and chronic suppurative lymphadenitis, respectively. A case of metastatic carcinoma showed smears composed of RS-like cells in a reactive background. These cells turned out to be large binucleated epithelioid and giant cells exhibiting total lymph node effacement. Incidentally, the initial preimmunohistochemical diagnosis on histology was NHL. Immunohistochemistry was, however, negative for CD3 and CD20 but positive for AE 1/3. Alam et al.[30] concluded that the discohesive nature of cells in poorly differentiated metastatic carcinoma may be confused with anaplastic large cell lymphoma or DLBCL on cytology. To obviate this erroneous interpretation, the authors showed that identification of background cytoplasmic fragments and lobulated nuclei were features that favor lymphoma diagnosis on cytology.

 Conclusion



Intra abdominal lesions were more concordant than oral/maxillofacial lesions while lymph node lesions were the least concordant.

Limitations

The most reported concordant lesions are pleomorphic adenoma, Burkitt's lymphoma, nephroblastoma, neuroblastoma, tuberculosis, and metastatic carcinoma of lymph nodes. These were not included in the current study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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