ABSTRACT

Corresponding Author:
Dr. Aparna Dutta,
Assistant Professor,
Department of Pathology,
Assam Medical College & Hospital,
Dibrugarh-786002, Assam.
E-mail: draparnakamal@gmail.com

ABSTRACT

Soft tissue tumors presents a challenge to the medical professional because of their extremely varied morphology and biologic behaviour. There has been a growing enthusiasm for the aspiration cytology technique in diagnosing soft tissue tumors due to the possibility of providing rapid and adequate pre-treatment diagnosis, the low cost of the procedures and the minimal risk of complications.

OBJECTIVE

To evaluate the value of FNAC in diagnosis of soft tissue tumors and establish its accuracy by histological correlation.

MATERIALS AND METHODS

Fifty two cases of soft tissue tumors were aspirated in the Dept. of Pathology, Assam Medical College and Hospital, Dibrugarh. The aspirates were air-dried and wet-smear fixed in 95% alcohol and stained with MGG and PAP respectively for light microscopic examination. The surgically excised tumors were formalin fixed; paraffin embedded, sections made and stained with H and E for histopathological study.

RESULTS

Out of 52 soft tissue tumors, 37 were benign tumors and 15 malignant ones. In the benign tumors, 89.19% showed consistent results and 8.11% showed inconsistent results. In the malignant group, 93.33% showed consistent results and 6.67% inconsistent results. There were 14 true positive cases, 33 true negative cases, one false positive case and one false negative case. The overall accuracy of 90.38% was achieved.

CONCLUSION

FNAC has significant efficacy in the diagnosis of the soft tissue tumors when combined with detailed history, clinical examination and radiological investigations.

KEYWORDS

Soft Tissue Tumors, Fine Needle Aspiration Cytology.

INTRODUCTION

With the control of infectious diseases and increased longevity of the growing population, the spectrum of disease changes and the burden of cancer is on the increase. Early diagnosis of cancer has thus become indispensable for cancer control and prevention and the technique of FNAC is becoming a highly creditable diagnostic approach throughout the world.

The technique of fine needle aspiration was first reported by Kun in 1847, but it was Scandinavian Clinician and Pathologist teams who popularized this technique. FNA has proved effective and reliable in the study of primary or metastatic epithelial neoplasms.

Sensitivity – The sensitivity is the ability of a test to identify correctly all those who have the disease.

DISCUSSION

Since the inception of fine needle aspiration more than 50 years ago by Martin and Ellis, 1934, it has travelled to its present popularity over a tortuous road. Fine Needle Aspiration Cytology (FNAC) is well established for evaluation of epithelial tumors for many years. However, only a few published series discuss the FNA cytology of soft tissue tumors and many of these reports contained large number of cases of metastatic carcinoma. Most clinicians dealing with soft tissue lesion are reluctant to accept FNAC diagnosis in determining the treatment modality, chiefly in view of the poor morphological expression in aspirates tumor heterogeneity.^[7] focal natures of certain sarcomatous growth.^[8] and the limited individual experience of the cytopathologist because of lower incidence of sarcoma. Nevertheless, the cytologic and architectural findings published over the last few years, taken in conjunction with clinical and radiologic data enable cytologic diagnosis to be as precise as those reached through histologic examination in experienced hand.

Aspiration of soft tissue tumors were performed with 22-gauge fine needle following the technique of Zajicek et al.^[9] Sufficient material was obtained in all cases except 3 cases (5.8%). Akerman et al.^[5] with his experience of aspiration of soft tissue tumor in 1980 and 1985 had reported insufficient material in 5% and 8% cases respectively. However, series of 17% cases with insufficient material had been reported Layfield et al. 1986.^[10]

In the present series, 2 cases of haemangioma could not be diagnosed due to the presence of blood in the aspirates. Similar difficulty was also faced by Akerman et al.^[5] and Roy et al.^[11] in vascular tumors. Cell material mixed with much blood is difficult to interpret, as the cells become packed together and are covered by erythrocytes. In case of extra-skeletal bone tumors and cartilaginous tumors, diagnostic difficulty was faced due to insufficient material and difficult of aspiration with 22-gauge needle. Similar problem was reported by Stormy et al. 1973.^[12] Our study included 52 cases (Histologically correlated) of soft tissue tumour were diagnosed (4.84%) out of total 1076 other neoplasms (95.15%).

Similar incidence, i.e. 3% was found by Roy et al. in his series.^[11] In the present study, highest number of cases was found between 21-30 years and 31-40 years. In the malignant category age group had gone one step higher, i.e. between 40-60 years of age. According to Enzinger and Weiss.^[13] soft tissue sarcoma can occur at any age, but are more common in older patients (>50 years), which is comparable to the present series.

A male preponderance was seen in this series giving the male-to-female ratio of 2.25:1.

The clinical findings and radiologic patterns manifested by soft tissue tumors in the present series were diverse and non-specific. But radiology was of help in one case of chondrosarcoma, two cases of Ewing’s Sarcoma and in one case of neurofibroma. Enzinger and Weiss.^[13] also stressed on the fact that masses rising in the subcutaneous and deeper soft tissues should be evaluated by radiologic studies, which can detect calcification, ossification or radiolucency within the lesion and can differentiate whether a lesion is primary in soft tissue or primary within bone.

The most common sites of presentation of benign STT were in the extremities, head and neck. In the malignant group, sarcomas were more commonly found in the lower extremity (53.33%) followed by trunk and chest wall. In the present series, round cell sarcomas were more commonly found on lower extremities, which is comparable to that found by Roy et al.^[11]

In the present series, the benign tumors included mostly lipomas (43.2%) and benign fibrous histiocytomas.

In our study, the overall diagnostic accuracy was found to be 90.38% (i.e. 47/52 cases). M. Akerman et al.^[5] reported the total reliability of FNAC around 85%; Kulkami et al. in 2002.^[14] found overall accuracy in 93.33% of all soft tissue tumor.

The definite cytologic diagnosis like its histologic counterpart was based on correct evaluation of clinical data, radiologic information and cytologic findings (Architectural pattern, cell and stroma characteristics). The final cytology report placed the tumor in one of the three basic categories: Benign, malignant and inconclusive. The last category included insufficient aspirates. In our study, insufficient material was obtained in 3 cases (5.8%).

The aspiration of neural tumors (Neurofibroma and neurilemoma) yielded very scanty material. Aggregates of spindle cells with abundant cytoplasm and elongated nuclei were found in cases of neurofibromas. FNA yielded cohesive spindle-shaped cells with indistinct cytoplasmic boundaries within fibrillary mesenchymal background. The nucleus of the cells were slender and pointed. ‘Verocay bodies’ could not be demonstrated in neurilemoma in the present study, probably due to lack of cellular aspirates. In the present study, a case of haemangioma revealed only blood cells in aspirates and so could not be diagnosed. Similar difficulties was also faced by M. Akerman et al.^[5] Out of total 6 cases of benign fibrous histiocytoma, 2 cases of benign fibrous histiocytoma were misinterpreted due to scanty material. One case revealed only few fibroblast-like cells and fat cells, so misinterpreted to be fibrolipoma. Another case revealed only blood cells and thus rendered to be inconclusive. In our experience, aspirates of BFH revealed cells with abundant cytoplasm and nucleus having prominent nucleoli and few fibroblast like cells in a haemorrhagic background.

One case of benign granular cell myoblastoma of neck was diagnosed by FNAC as a soft tissue tumors and was later confirmed by histopathology. The smear by MGG stain showed a uniform population of cells with eccentric nuclei and a granular cytoplasm.

Three cases of fibroma was diagnosed cytologically and later confirmed by histopathology. The aspirates of fibroma revealed mostly spindle shaped cells with scant cytoplasm and elongated nucleus in an inflammatory background.

In the sarcoma group, out of total 15 cases one case was misdiagnosed as benign tumor. The case was of a 60 years male with a thigh swelling. The cytology report was inconclusive and thought to be benign fibrohistiocytic tumor. Histopathology diagnosed the case as rhabdomyosarcoma. Thus, in our study false negative was 6.67% which is comparable to that found by M. Akerman et al. (7%).^[5] and Kulkami et al.^[14]

In our study, out of total 52 cases there were 14 true positive cases, 1 false negative case, 33 true negative cases and 1 false positive case.

Sensitivity of the series is 93.33% and specificity 97.06%. The overall accuracy rate is 90.38%. These rates compared favorably with the aspiration results from parenchymal organs, such as the breast.^[15] and thyroid gland.^[16] There is considerable variation in the consistency of benign and malignant tumors. Benign tumors shows a consistency of 89.18% and malignant tumor shows 93.33% consistency.

The results and observations made in the present series are compared with other studies as shown in the table.

In our series, there was one false positive (2.10%) and one false negative (6.67%) reports as far as malignancy was concerned. These findings are comparable with other studies cited above.

Our experience with FNA cytology of soft tissue tumors indicates that it is a useful and convenient technique for the diagnosis and follow-up of patients with these tumors. Clinical information was an extremely helpful adjunct to cytologic examination and in many cases was necessary for accurate diagnostic interpretation.

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