Fine-needle aspiration cytology (FNAC) is a simple, cost-effective procedure which is widely used to diagnose lesions in various sites but has a relatively less utility in bone lesions. when compared with core biopsy, FNAC is painless and cost-effective, has a lower risk of tumor seeding and gives an early diagnosis with minimal disruption of lesion.[1]

However, FNAC has not been widely applied in the diagnosis of bone masses. This could be due to technical problems, the morphological heterogenesity of bone tumors and anticipated difficulty in obtaining adequate tissue material chiefly due to limited experience.[2] FNAC when coupled with proper clinic radiological correlation is an effective, precise tool and can be the procedure of choice in diagnosis of bony lesions with biopsy being the final staging procedure. The present study attempts to find out the efficacy and reliability of FNAC in diagnosing bone lesions. With the development of neoadjuvant chemotherapy and new orthopaedic surgical techniques like salvage limb procedures to treat primary malignant bone neoplasms, there has been an enhancement of the role of FNAC in the management metastatic as well as primary malignant bone tumors.[3]

The study was undertaken to assess the role of FNAC in the evaluation of various space occupying lesions of bone assess its sensitivity and specificity compared to core needle or open surgical biopsy.

Aims & Objectives

1. To evaluate the efficacy of FNAC in the pre operative diagnosis of bone lesions.
2. To compare FNAC and core needle biopsy (CNB) in space occupying lesions of bone.
3. Statistical evaluation of sensitivity, specificity, positive predictive value, negative predictive value & p value.

All the patients referred from ORTHOPAEDICS OPD to the Cytology section of Dept. of Pathology of SCB MCH, Cuttack were included in this study. Detailed clinical and radiological history of each patient was obtained in standard format prior to cytological evaluation.

Study Location:

SCB MCH, Cuttack

Study design:

(Cross-sectional) Observational study

Study Period: - Sept 2020-Sept 2022

INCLUSION CRITERIA

1. Clinically & radiologically diagnosed patients of bone lesions.
2. Patients willing to give consent for the procedure.

EXCLUSION CRITERIA

• Patients unwilling to cooperate.

FNAC was performed under strict aseptic precautions and local anaesthesia was given when required. Slides were fixed in isopropyl alcohol and stained with Haematoxylin and Eosin. Slides were examined under the light microscope and results were recorded in the master chart.

1. Staining Procedure:
2. Haematoxylin and Eosin (H. & E.)
3. Diff Quik
4. Papanicolaou (Pap)

The cytosmears were coverslipped. Those cases who underwent surgery, had a histological follow up. The tissue samples were received for histopathological examination with proper labelling which included name of the patient, age, sex, registration number and clinical diagnosis. The gross examination was done to document the size, shape, evidence of hemorrhage and necrosis or any special gross features.  Multiple tissue sections were taken from the representative areas for processing. In case of small biopsies entire specimen was directly processed

This study included 67 specimens of various benign and malignant bone tumours and tumour – like lesions. The various benign tumours diagnosed were osteochondroma, enchondroma, chondromyxoid fibroma, osteoid osteoma, osteoblastoma and giant cell tumours. The malignant tumours diagnosed were chondrosarcoma, osteosarcoma, Ewing sarcoma, malignant giant cell tumour. Tumour – like lesions were received and included aneurysmal bone cyst, fibrous dysplasia. The distribution of bone lesions in our study is shown in Char-1.

Chart-1: Frequency Of Bone Lesions

Malignant tumours accounted for more than half the percentage of lesions (50.7%). Benign tumours constituted 37.3% of the samples received. Tumour – like lesions were the least frequent constituting only 12% of all cases.

The gender distribution of the cases has been shown in Table-1 and Chart-2

Table-1 - Age And Gender Distribution Of Cases

Chart-2: Age And Gender Distribution Of Cases

The distribution of cases based on presenting symptoms has been shown in Chart 3

Chart 3 - Distribution of presenting symptoms

47% of the patients presented with swelling as their chief complaint. Pain along with swelling was the next common complaint (20.8%).

Table 2: Distribution Of Bone Lesions Based On Bone Involved.

The commonest bones involved were femur, tibia and humerus with 40%, 22.1% and 16.8% cases respectively. 

41.7% of the lesions occurred around the knee joint (distal femur and proximal tibia). Involvement of the axial skeleton occurred in 5.9% of the cases. Small bone involvement was seen in 6% of the cases.

Chart 4 - Distribution Of Bone Lesions Based On Site Of Involvement

Distribution of cases based on histopathologic diagnosis has been shown in Table 5 and Chart 6.

Table 3- Distribution Of Cases Based On Histopathological Diagnosis

The commonest tumour encountered in this study was osteosarcoma (26.8%). Giant cell tumours and chondrosarcoma were the other common tumours amounting to 16.9% and 10.4% respectively.

Degree of freedom = (No. of columns -1) (No. of rows -1) = (2-1) (2-1) =1x1=1

Chi square value calculated= 38.9328

The p value is <0.00001

This result is significant at p<0.05. Hence our study is statistically significant.

Radiograph, CT scan, specimen, Pictomicrographs of histology & Cytology of bone lesions are given below:

Fig.1- Anteroposterior radiograph of an osteochondroma involving right femur. Lesion characteristically pointing away the joint.

Fig.2 – Osteochondroma. Contrast enhanced axial CT section of pelvis showing an exophytic lobulated cortical from mass arising from right iliac blade with medullary continuity.

Fig.3 - Osteochondroma with cartilage cap. Chondrocytes have an orderly arrangement in the cartilage cap and there is maturation into trabecular bone. (H&E scanner view) Inset shows columnar arrangement of chondrocytes towards the base. (H&E x 400)

Fig.4 - GCT of distal femur. Plain radiograph in AP view shows expansile lytic lesion in distal femur

Fig.5,6 - FNAC from a case of GCT showing spindle shaped stromal cells and osteoclastic giant cells. (H&E x 400)

Fig.7- Proximal tibial resection for recurrent GCT. Characteristic red brown tumour destroying the cortex.

Fig .8-Slide showing core needle biopsy sample of GCT

Fig .9– CNB of GCT – Multi nucleated giant cells arranged uniformly in a background of mononuclear cells.

Fig.10- Clinical presentation of osteosarcoma distal end of tibia with fibular involvement.  Ulceration due to stretching of skin by the tumour.

 Fig.11 - Osteosarcoma distal tibia with fibular involvement. Plain radiograph. Mixed lytic – sclerotic mass with sunray reaction. Cloud like matrix mineralisation seen.

Fig. 12 Specimen of humerus by shoulder disarticulation procedure

Fig .13,14- Osteosarcoma; malignant stromal cells with osteoid production. (H&E Scanner view & x400)

Fig.15,16 - Osteosarcoma with giant cells. The nuclei of malignant stromal cells are pleomorphic and vesicular as against benign looking nuclei of giant cells. (H&E x 400)

Fig.17: cytology of chondromyxoid fibroma showing 2 cell population round to oval and spindle to stellate in a chondromyxoid matrix(H&E x 400)

Fig.18,19 biopsy of CMF showing hypo and hyper cellular area in a lobular pattern(H&E scanner & x 400)

Fig 20,21: FNAC of chondrosarcoma shwoing cellular and pleomorphic cells in chondroid matrix H& E 400X

Fig.22 -  Grade-II chondrosarcoma. Increased cellularity, nuclear enlargement and hyperchromasia. (H&E x 100)

Fig.23- Binucleated chondrocytes. Moderate nuclear atypia and pleomorphism in grade II chondrosarcoma. (H&E x 400)

Fig.24: FNAC of Ewing sarcoma(H&E x 400)

Fig.25,26 - Ewing sarcoma. Sheets of tumour cells with uniform round nuclei. Rosette formation seen. (H&E x400). Inset shows membrane positivity of tumour cells with CD99 immunostain.

Tumours of bone are not uncommonly encountered in clinical practice. The low incidence of these tumours and the resulting limited experience in dealing with them adds to the diagnostic difficulties. Clinico – radiological evaluation of bone tumours and tumour – like lesions is an essential part of patient management. Recognition of FNAC as a diagnostic tool for bony lesion has been largely hindered by the inability to obtain adequate smears. The use of fine needle aspiration for the diagnosis of lesions of bone was noted as early as the 1930s (Coley et al., 1931)[4]. However its use was mostly limited to the diagnosis of metastatic malignancies to bone and assumed a less important tool the diagnosis of primary neoplasms (Layfield, 2009).[5]

The aspiration was successful in almost all cases and adequate material was obtained in 65 cases for cytological interpretation. Similar observations were made by Ostrowski et al. (2009)[6]; Sudipta Chakrabarti et al. (2012)[7]. The cases where aspirated material contained blood, was immediately soaked and smears were made as quickly as possible from the tissue fragments to prevent the formation of clot and entrapment of tissue fragments in it. A Jamshidi (J) needle was used to obtain a core of tissue and specimens were sent for histopathological examination. Biopsy results were analysed for adequacy, ability to yield diagnostic information and for accuracy of diagnosis.

Ethanol fixed smears prepared from aspirates were stained with Haematoxylin and Eosin stain or Papanicolaou stain .Haematoxylin and Eosin (H & E) and Papanicolaou staining procedures were less time consuming than May - Grunwald - Griemsa (MGG stain). But MGG stain was particularly helpful in detecting chondroid matrix and calcification in cartilaginous tumours. Similar observations were experienced by Kumar et al. (2016) and Pohar - Marinsek Z. et al.[8-9]

The comparison of data from different studies for classification of bone lesions based on behaviour has been shown in Table-4.

Table-4 Comparison of data from different studies done on classification of bone lesions based on behaviour

FNAC was found to have high sensitivity (86.1%), specificity(90.3%) as a diagnostic procedure for bone lesions in present study.In study by Vangala N et al(2021)[13]  sensitivity and specificity showed to be 93.33% and 92.86% respectively.Overall rate of accuracy was 88.0% in present study where as Rekhi B [12] et al 2019 study had a higher accuracy of 93.1%  .In our series of 67 cases, of aspiration of the skeletal system, no complications were seen and the patients were extremely compliant. Similar observations were made by various authors as regards aspirations as a diagnostic procedure of the skeletal system lesions.

The various advantages of this procedure are :

1. FNAC has fewer complications with a lower risk of tumor seeding post-FNAC, and the aspiration site has minor microscopic changes that does not affect the histological diagnosis.
2. Ancillary testing can be done on the cytology/cellblock material.
3. Based on just the FNAC diagnosis, treatment can be initiated at an early stage especially for infectious conditions like tuberculosis as well as chemosensitive tumors like Ewing sarcoma and lymphoma.
4. The rate of inadequacy in our study was comparatively lower than in other similar studies, and the reasons for this could be a cytopathologist performing the procedure with proper radiological correlation.

The major drawbacks of FNAC of bone lesions include:

1. difficulty in diagnosis of sclerotic lesions and inaccurate subclassification and grading of lesions especially low-grade sarcomas. CNB is preferable and is the gold standard for diagnosis in such lesions.
2. specimen inadequacy. Review of literature reveals that the rate of inadequate aspirates in bone cytology ranged from 3 to 33% . The present study had a specimen inadequacy rate of 15%.
3. On subsequent histological correlation, most of these cases of inadequate smears were from benign lesions especially ABC and osteoblastoma.
4. Cartilaginous tumors are frequent source of error.
5. inadequacy may be due to combination of factors like difficult location to aspirate (spine), presence of prominent osteoid matrix.

From the present study as well as review of literature reported in this field it is observed that bone FNAC is a simple, cost-effective, and accurate preoperative diagnostic procedure aiding in limb-sparing reconstructive techniques.[13] When compared with coreneedle biopsy (CNB), FNAC is a minimally invasive, safer, quicker, inexpensive technique and specimen adequacy can be assessed immediately at the time of procedure. When performed under radiological guidance[14-15], it is preferable over CNB, as it provides more access to lesions at a deeper location, especially those with a soft-tissue component. FNAC has fewer complications with a lower risk of tumor seeding post-FNAC, and the aspiration site has minor microscopic changes that does not affect the histological diagnosis.

In order to evaluate the function of guided fine needle aspiration cytology in the identification of bone tumors, 67 patients suspected of having osseous tumors based on clinical and/or roentgenologic criteria were examined between September 2020 and September 2022. A thorough physical examination, radiologic findings, and a brief clinical history were all documented. A 22G-24G needle connected to a 10ml syringe was used to mark and aspirate the lesions. Under a radiologist's imaging supervision, aspirations were made in several instances with thick, intact cortex. All 67 instances underwent further histological analysis of the tumor tissue using either an open biopsy or a core needle biopsy, depending on which was more advantageous.Giant cell tumors were the most prevalent benign and intermediate lesions among the 67 cases that were examined. Among the cancerous

Among malignant tumors, osteosarcoma accounted for the most frequent 18 instances (26.85%), with chondrosarcoma coming in second. 7 instances (10.44%)The majority of those afflicted were men. Five instances (7.46%) had either hemorrhagic smears or little material, making interpretation impossible.

The most often impacted area was the area surrounding the knee joint. Three instances (4.47%) in the series had metastatic tumors. The majority of incidents happened to people between the ages of 10 and 19 and 21 and 40.In the series, there were only three false positive cases and five false negatives.

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