Diagnostic Significance of Fine Needle Aspiration Smear and Cell Block Study in Skin and Subcutaneous Nodules

Raafat AM Hegazy^1*, Abdelmonem AM Hegzy² and Ahmed Raafat Hegazy^3
*Correspondence: Raafat AM Hegazy, Department of Pathology,Faculty of Medicine, Zagazig University, Egypt, Tel: 00201153772990, Email:

Keywords

Biopsy • Cell Block • Skin • Subcutaneous Nodules

Introduction

Skin and subcutaneous nodules are just elevation of skin contexture more than 5 mm [3]. The depth is more important than width. The skin nodule may be mobile or fixed to the underlying tissues. The prober management needs to know about its exact nature, whether benign or malignant. These nodules are accessible for needle aspiration, to perform smears and cell blocks; this action is non-invasive, without need of operating theater, or anesthesia. Also, it is cheap and rapid procedure. The question is about its sensitivity, and specificity, and to much how we can depend on, in taking the decision of treatment.

Methodology

Two hundred twenty five patients suffering from skin or subcutaneous nodules were selected for this study. These patients were attenders in the outpatient clinics of surgery and pathology department in the period between January 2018 and December 2020. The patients underwent full history taking, general examination for pulse, temperature, respiration rate, body weight, length. The nodules under study were examined clinically, in site, size, multiplicity, shape, consistency, color, if there`s hair or not, if there`s change in color, size, shape, mobility or fixation. Then, A 20cc plastic sterile syringe is opened, about 1cc of air is taken, and the cover is placed on the needle and become ready for use. The skin or subcutaneous nodule underwent gentle massage by a cotton gauze filled with 95% ethanol, then introduce the needle near the periphery of the nodule (avoid the center where there may be necrotic material that hinder proper smear taking). The needle was moved in multiple directions with suction. Then the syringe is removed gently. The site of aspirate underwent compression by clean, sterile cotton gauze for at least 10 minutes to stop bleeding. The needle is gently dislodged from the syringe, then one drop is placed from the syringe on about 4 clean glass slides. The smear is prepared by gentle moving of the blunt end of the syringe. The remaining part of fluid underwent addition of 10% neutral buffered formalin by gentle suction of the previously prepared formalin by the syringe. The smear is left to about to dry on the glass slides, then the slides were placed vertically in the staining jar, the addition of 95% ethanol, left for 20 minutes for fixation. The fixed smear slides are placed gently in water for one minute, and then placed in filtered hematoxylene for 5 minutes, then in tap water for 30 minutes, then in eosin for one minute the tap water for 20 minutes. The slide smear then, underwent placing in ascending grades of ethanol till absolute alcohol. A cover is placed and then examination of the smear by the Olympus XL 30 binuclear microscope. The pellet of cells in the used syringe, is left for one day for fixation, then underwent processing to form paraffin blocks, according to Hegazy method of tissue processing [4]. Unstained slides are prepared from the paraffin blocks then staining with Hematoxylene & eosin, Giemsa stain, Papaneacolou stain. Then slides are examined by the Olympus XL30 binuclear microscope, imaging using the digital camera on microscope. The patients in this study were underwent FNAC smears examination, cell blocks performance if possible then histological examination of tissue biopsy.

Statistical analysis

The correlation between results of FNAC smear and that of Cell block study was examined by chi-square test and student T-test.Sensitivity test, & Specificity test for both FNAC smear and cell blocks were examined in relation to the tissue biopsy, considering the results of tissue biopsy examination as the reference positive cases. All statistical tests were done with considering the significance value of chi-square test and T-test (p value=0.05 or less) using SPSS 16.0 for Windows (SPSS Inc. Chicago, Illinois, USA).

Results

There was a wide range of age in the patients underwent this study; ranging from 2 years to 76 years old, but most of them (80%) were at the range of 40-45years. The genders of patients were mostly female; female: male, 10:1.

Results of FNAC smear, cell block examination and Tissue biopsy examination were summarized in (Tables 1-3).

The most relevant pictures of microscopic examination were placed in figures (1-10). Sensitivity and specificity test results of both FNAC smear examination and Cell block examination are summarized in the following data,

For the FNAC smear examination:

• True positive cases= 220/225

• True negative cases= 5 /225

• False positive cases=25/225

• False negative cases= 45/225

• Sensitivity test = 220/220+45= 220/265=83.01%

• Specificity test= 5/5+25=5/30= 16.66%

For the cell blocks examination:

• True positive cases= 220/225

• True negative cases= 5 /225

• False positive cases= 0/225

• False negative cases=5/225

• Sensitivity test= 220/220+5=220/225=97.77%

• Specificity test= 5/5+0=5/5= 100% (Figures 1-10)

Discussion

In this study, we concentrate on cell block performance, and its importance in diagnosis and differentiation of the lesion because of its simplicity, reproducibility. We perform FNAC smear first, as it is a rapid test, to find out the presence of cells, their types generally. Also to compare the features found in FNAC smear and that of cell blocks. We utilized the clot method for preparation of cell blocks, other methods were described by, Shidham2019 Satturwar and Pantanowitz 2021 [5,6]. These include the gel-based method (including gelatin-based, agar based, Histogel methods), coagulation-based methods (including Chemical mechanism: Egg albumin‑Alcohol, Alginate‑calcium, Shandon Cytoblocmethod, Picrate‑based, Enzymatic coagulation (Enzyme‑based methods, Plasma/ fibrinogen‑thrombin The preformed supporting media (including: Celloidin method, Millipore filters, Various foams such as Gelatin foam and foam core device. Other methods E.g: cellient alcohol, in addition to the clotting method. We prefer the clotting method because the structural forms of cells and tissues are more preserved. We utilize the same clotting method in preparation of cell blocks in two previous studies and gave excellent results [7,8]. The patients in this work ranged in age, between 2 to 76 years with more shift to the old age (>40 was about 70%), and female to male ratio was 3:2, without significant outcome. This meant that the appearance or the complaint of skin or subcutaneous nodules occur more in females and in older ages >40 years). For FNAC smear results; the test processed a sensitivity about 83%, that is a significant percentage but lower than that of cell block (97.77%), this meant that cell block is more sensitive test than FNAC smear. Also, Cell block technique is more and more specific than FNAC smear, (100%) for cell block, and16.66% for FNAC smear). These results alluded to the role of cell block in appearance of cell orientations, which give a picture resembling the tissue biopsy.

In case of benign cyst; the cyst is filled of fluid, so the smear contain scanty cells, which may not appear, and the smear gives insufficient result, Cell block gives more accurate result, but the performance of cell block may fail because of low cells, and need gentle handling. In case of seborrehic keratosis; the smear was insignificant, because the cells were degenerated, with more brown pigment out cells, the features of cells were vague. On contrast; in cell block; the features of cells (benign features are more obvious). This picture gives a confidence in diagnosis as a benign lesion. In cases of lipoma, and fibrolipoma; the smear showed fat globules and/or mature fat cells, sometimes, fibrous elements a picture found by other authors [9], these features give a confidence of benign lesion, but the specific diagnosis cannot be achieved. The specific diagnosis of lipoma, fibrolipoma can be given easily in cell block. In cases of fibroma; the smeargive a suggestion of benign fibrotic lesion (spindle-shaped fibroblasts and some collagen fibers), but the cell block showed well-formed fibroma. In cases of juvenile fibromas; the smear may be negative because of the dense contents, however the cell block is specific for diagnosis, moreover, it takes another importance to exclude juvenile fibrosarcoma and fibromatosis (the absence of mitotic activity). On contrary of the previous lesions; FNAC smear gives a satisfactory results that differentiate a benign lesion, and also specific for neurofibroma; because it gives us a picture of twisted nuclei, angulated and a hair-like background of neurofilaments a feature also found by Abdellatif and Kamel [10]. In cases of pilomatrexioma; the smear gives a picture of benign lesion (ghost cells, mature epithelial cells, giant cells) the same picture found by Bansal et al. [11], but the cell block failed in most cases because of the presence of admixed amounts of degenerated, or shadow cells. In cases of dermoid cysts or implantation cysts; the smear showed a mixture degenerated epithelial cells and keratinous material a picture found also by Vaughan and Wisell [12], but the cell block also usually fails, due to the keratinous material.In cases of atypical lipomas; FNAC smear gives us a very useful picture; pleomorphic, hyperchromaticlipoblasts, mucoid background, the cell block dose not add a more information.In cases of basal cell carcinoma; FNAC smear showed malignant cells with basophilic cytoplasm the same results were found by Pasquali et al., but the orientation of cells appear in the cell block (peripheral palisading) [13]. In cases of squamous cell carcinoma; the malignant epithelial cells and the individual cell keratinization appearin the smear. The FNAC smear gives a good picture but the specific feature of cell nests and keratin pearls appear in the cell block. In cases of FNAC smear of basosqaumous cell carcinoma; the smear gives a picture of malignant epithelial cells, but the specific orientation of basosqaumous cell carcinoma appear in the cell block.In cases of Madura foot; the smear showed mixed inflammatory cell infiltrate which is non-specific, but cell block is very useful to clarify the mycetoma colonies with peripheral esinophilic clubs appear, however Afroz et al., could found this feature in the FNAC smear [14].

Conclusion

Cell block study gives a more specific and more orientation of the cells like that of tissue biopsy. FNAC smear may give a useful features. Some lesions give negative results in smears, others give negative results in cell block, Therefore we recommend to perform FNAC smear and also cell blocks whenever possible.

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