Material and Method: We retrospectively studied 510 consecutive fine needle aspiration cytology findings of cases from North Bengal Medical College and Hospital and correlated their diagnoses based upon cytological and histopathological grounds.
Results: Out of the 510 cases studied, 253 were non neoplastic lesions and 257 were neoplastic. A high degree of concordance was observed (100% for malignant and 96.15% for benign lesions) when these two diagnostic modalities were compared. Histopathological correlation was possible in all malignant, 52/189 (27.51%) of benign and 27/253 (10.67%) of non-neoplastic lesions. Sensitivity and specificity of diagnoses were 95.31% and 97.6%, respectively.
Conclusion: It can be safely concluded that fine needle aspiration cytology is a rapid, reliable and fairly accurate tool for initial triage and treatment of skin and superficial soft tissue lesions.
The common difficulties encountered in cytological diagnosis of primary soft tissue neoplasms are their overlapping cytomorphological features, heterogeneity in some of the mass lesions and the increased recognition of borderline (intermediate) lesions[2].
FNA was performed for diagnosis in all cases. Skin scraping was done for superficial ulcers and ulcerated tumors. Tissue biopsy samples were obtained for 147 patients (28.82%). Excisional, incisional and punch biopsies were done for histopathological examination in 78.23%, 7.48% and 14.29% of the patients, respectively. Under aseptic precautions, fine needle aspirations were performed using a 21 gauge needle by palpation by pathologists. For most of the cases a single pass well sufficed. For larger lesions, 2 or 3 separate passes were made. Cytological smears were stained with Hematoxylin-Eosin (H&E) and Leishman-Giemsa for all cases. Ziehl-Neelsen (ZN) staining was performed for 13 cases. Histologic sections were routinely stained with the H&E stain. Concordance rates between cytological and histopathological diagnosis were analyzed.
The study was approved by the Institutional Ethics Committee.
Table I : Distribution of patients by age and sex
Epidermal inclusion cyst (EIC) was the most frequently encountered non neoplastic lesion (135 cases 53.35%). Other common lesions were acute suppurative lesions (65 cases 25.69%), ganglion (21 cases 8.92%) and granulomatous lesions (28 cases 11.06%). Three cases of calcinosis cutis and a single case of soft tissue filariasis were noted (Figure 1). Out of the 13 cases reported as granulomatous lesion, 10 showed acid fast bacilli in ZN smears.
Among the benign neoplasms, lipoma was the predominant lesion (76.71%). Other common lesions were benign spindle cell neoplasms (14.28%) and vascular lesions (3.17%). We found a few cases of neurofibroma, schwannoma and benign fibrous histiocytoma that where cytologically diagnosed as benign spindle cell lesion. We came across 3 cases of benign adnexal lesion among which one was diagnosed as pilomatrixoma (Figure 2). The other two could not be specifically typed but both were histologically diagnosed as pilomatrixoma. An erroneous diagnosis of EIC was given in 2 cases but later they were histologically confirmed to be pilomatrixoma (Table II).
Table II: Distribution of benign neoplasms
There were 68 malignant tumors with an age range of 2-65 years. Among the malignant tumors, squamous cell carcinoma was the most common (69.11%) followed by malignant spindle cell lesion (11.76%) (Table III).
Table III: Distribution of malignant neoplasms
The youngest of our cases was a 2-year-old boy who presented with a swelling in the left upper eyelid and was diagnosed as embryonal rhabdomyosarcoma (Figüre 3A,B). Out of the 8 cases reported as malignant spindle cell lesions, 3 were provisionally diagnosed as MPNST out of which 2 were confirmed histopathologically and the other was finally diagnosed as monophasic synovial sarcoma (Figure 4A,B). Among the other 5 cases, 3 were finally diagnosed as fibrosarcoma and 2 as angiosarcoma. Specific typing could therefore be done in just 25% of the cases for these type of lesions.
One rare case of extraskeletal plasmacytoma was reported, developing in the scalp of a 6-year-old boy and is a very unusual site for this neoplasm (Figure 5). The smears from the 4 cases of malignant melanoma that presented as pigmented cutaneous nodular lesions demonstrated pleomorphic melanocytes having atypical hyperchromatic nuclei and intracytoplasmic melanin pigment (Figure 6A,B).
Histopathological correlation was possible in all malignant, 52/189 (27.51%) of benign and 27/253 (10.67%) nonneoplastic lesions. Sensitivity and specificity of the diagnoses were 95.31% and 97.6%, respectively. The concordance between cytological and histological diagnosis was noticed in all the malignant (100%) and 50/52 (96.15%) of benign lesions.
In our experience, histopathological correlation was possible in all malignant and 27.51% of benign neoplasms whereas the sensitivity and specificity of diagnosis was 95.31% and 97.6%, respectively.
It was seen that biopsy provided complete tissue details for accurate diagnosis; however, diagnosis takes a longer time as compared to the early diagnosis provided by cytology. Yet it may not be readily available, as is evident from this study, where 137 cases reported as benign neoplasm in the cytopathological report did not comply with a request for biopsy.
The concordance between cytological and histological diagnosis was noticed in all the malignant (100%) and 50/52 (96.15%) of benign lesions. Thus, a considerably high degree of concordance was achieved among cytological and histological modalities of diagnosis.
Only two cases of pilomatrixoma were misdiagnosed as epidermal inclusion cysts. The main reasons behind the erroneous diagnosis was the selective sampling of squamous cells. These findings are in concordance with a previous study by Bansal et al.[4].
Lipoma was the predominant benign tumor (81.34%) in our study, keeping in concordance with the study by Beg et al.[5].
The most frequent malignant neoplasm encountered in our study was squamous cell carcinoma which is at par with the published literatüre[6]. Eight cases were reported as malignant spindle cell lesion cytologically. Among them 3 were provisionally diagnosed as MPNST out of which 2 were confirmed histopathologically and the other was finally diagnosed as monophasic synovial sarcoma. It may often be difficult to differentiate MPNST from monophasic synovial sarcoma (particularly the fibrous variant) only on morphological grounds without recourse to immunohistochemical or cytogenetic studies, which was also observed by Folpe et al.[7,8].
A histological diagnosis of fibrosarcoma was made in 3 cases and angiosarcoma in 2 cases. Thus, specific typing could be done in just 25% of the cases of these malignant spindle cell lesions. Exact cytological typing for these types of lesions were possible in 23.33% cases in a study by Rekhi et al.[3].
The aspirate from the 2 cases of embryonal rhabdomyosarcoma showed moderately pleomorphic small and large cells admixed with typical rhabdomyoblast like cells. Histological confirmation was obtained.
Interestingly, we also encountered a single case of extraskeletal plasmacytoma at an unusual site that revealed diffuse population of plasmacytoid cells. The smears from the 4 cases of malignant melanoma that presented as pigmented cutaneous nodular lesions did not pose any diagnostic difficulties. Five of our cases had a past history of ductal carcinoma of the breast and they presented with metastatic nodular deposits in the overlying skin that was evident cytologically.
FNAC proved to be of great value in the investigation of clinically suspected metastatic lesions, keeping at par with the studies undertaken by Wong et al., Rekhi et al. and Spitz et al.[3,9,10].
In conclusion, FNAC is a rapid, reliable and fairly accurate tool for initial triage and treatment of skin and superficial soft tissue lesions. However, it should be correlated with the clinical history, and histopathological and immunohistochemical studies wherever necessary for the final diagnosis and management.
CONFLICT OF INTEREST
The authors declare no conflict of interests.
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