Soft tissue tumors are defined as mesenchymal proliferations which occur in the extra-skeletal non epithelial tissues of the body, excluding the viscera, coverings of brain and lymphoreticular system [1]. Soft tissue tumours constitute a heterogeneous group of neoplasms in terms of clinical presentation, morphologic features and clinical behaviour [1]. The annual incidence of soft tissue tumor is 1.4 per 1,00,000 population[2]. Benign tumours outnumber malignant ones by 100:1[1]. Because of the rarity of primary tumors of soft tissue and large range of different types of tumours, the diagnosis and classification of soft tissue tumors becomes most difficult areas in surgical pathology and absence of recognisable tissue architectural patterns in cytological preparation makes diagnosis by fine needle aspiration cytology even more difficult [3].

However, FNAC is useful in distinguishing accurately between benign and malignant soft tissue tumours and also sub classify them into general, clinically relevant categories that permit initiation of therapy in many of the patients. In benign neoplasms, surgery can be avoided in the patients who are of poor surgical risk, and in malignant tumors, FNAC allows administration of a palliative treatment.

The main advantage of FNAC is its simplicity. It is a safe, cheap, relatively painless procedure, easy to perform without anaesthesiaand is acceptable to the patient [2]. It produces a speedy result and it acts as useful diagnostic technique in the initial diagnosis of tumours.

The present study was done to findout the efficacy of FNAC in the diagnosis of soft tissue tumors and in classifying benign and malignant tumours.

Type of study: This is a prospective cytohistological correlation study done at two tertiary care hospitalsin the Department of Pathology, Andhra Medical College and King George Hospital, Vishakhapatnam and Chalmeda Anand Rao Institute of Medical Sciences, Karimnagar.

Period of study: The present study was conducted over a period of one year between July 2018 and June 2019. A total number of 105 cases, 65 cases from King George Hospital and 40 cases from Chalmeda Anand Rao Institute of Medical Sciences were studied.

Most of tumors were observed between the age group of 21-50 years. Male: female ratio was 1:1.5 (Table-1).

Table-2: Anatomical distribution of various soft tissue tumors.

Majority of the tumors were observed in the lower extremity, followed by upper extremity (Table -2)

Table-3:Tumor size of various soft tissue lesions

Tumor size was highly variable irrespective of the grade of the lesion. Majority of benign tumors were <5 cm and malignant tumors were >10 cm in size (Table-3).

Table-4: Categorisation of soft tissue tumors on FNAC

Inadequate material was obtained in 10 (9.5%) cases. FNACsmears have been reported under three basic categories as benign, malignant and inconclusive or undetermined in this study. In 16/95 (17%) cases, the material yielded on FNAC was adequate but not sufficient to classify them as benign or malignant(Table-4).

Table-5: List of cases with inconclusive diagnosis

By convention, it also includes peripheral nervous system [3]. The annual incidence of soft tissue tumor is 1.4 per 1,00,000 population[4].

Because of the rarity of primary tumors of soft tissue and large range of different types of tumors, the diagnosis and classification of soft tissue tumors become most difficult areas in surgical pathology and absence of recognizable tissue architectural patterns in cytological preparation makes diagnosis by fine needle aspiration cytology even more difficult[5]. Benign tumors are more common than malignant counterparts with a ratio of at least 100: 1[6].

FNAC is painless, easy to perform, safe and cost effective without any anaesthesia and acts as a useful diagnostic technique in the initial diagnosis of tumors [7].

For distinguishing benign tumors from malignant tumors, FNAC was very useful except for exact categorization of tumors [8].

However FNAC as a preliminary diagnostic tool offers several advantages as it can provide a predictive diagnosis of a benign or malignant neoplasm. In benign neoplasm, surgery can be avoided in the patients who are of poor surgical risk, and in malignant or recurrent cancers, FNAC allows the administration of a palliative treatment [9,10].

In the present study adequate material was obtained in 95/105(90%) cases. The possible causes for inadequacy of material in the 10 cases were either due to aspiration of blood (in vascular lesions), collagen (desmoid type fibromatosis) or due to pain (in neural lesions). Collagen rich intercellular stroma, areas of hyalinization, fibrosis and prominant vascularity are known to influence the yield[11].

Gonzalez – Campora R stated that the final cytology report should place the soft tissue tumors in one of the three basic categories – benign, malignant and inconclusive or undetermined [12].

Table-8: Comparison of results on FNAC with other studies

Figure-3: Smears show syncytial sheet of pleomorphic spindle cells in MFH (H & E, x 100).

Figure-4: FNAC smears show loose sheets of large polygonal cells with abundant granular eosinophilic cytoplasm in granular cell tumor (H&E,x400).

In the present study 16 of 95 (17%) cases were labeled under the group of inconclusive diagnosis- that is even though the material was adequate for interpretation, it was difficult to classify them as benign or malignant (Table-4).3 of 16 (72%) were subsequently diagnosed as benign and 13 of 16 (72%) malignant on histopathology. Neoplasms arising from fibrous tissue have varied patterns on morphology.

It is essentially a diagnosis by exclusion. Fibromatosis, dermatofibrosarcoma protuberance, nodular fasciitis and low-grade sarcomas have almost similar morphology on cytology.

In the present study an accuracy of 95%, sensitivity of 82.6% and 100% specificity were observed which were similar to Maitra et al [13]. False negativity was seen in four cases, two liposarcomas, and two malignant peripheral nerve sheath tumors.

Limitations of the present study: Small sample size. The diagnosis on FNAC can be challenging because of interpretation and sampling issues.

From the present study, it was conclude that FNAC is an important tool in the preoperative diagnostic work up of soft tissue tumors with certain limitations and FNAC diagnosis is supplementary but not a substitute for histopathological examination.

FNAC distinguishes benign and malignant tmors of soft tissue with few limitations.

Dr. Lakshmi Saraswathi Boni: Conception of idea, took lead in writing the manuscript, done investigations

Dr. Sumalatha Kasturi: Verified the analytical methods, done investigations, manuscript writing

Dr. Prasad Uma: Data analysis, analytical calculations, interpretation of results

Dr. BhagyalakshmiAtla: Supervising the project

All authors provided critical feedback and helped shape the research analysis and manuscript.