Histopathological study of skin tumours

Background: Skin tumour and their various histological typesalways creating a diagnostic difficulty. Histopathology is the gold standard for diagnosis in turn is used by clinicians to aid clinical outcome andalso emphasizing certain key forvaluable observation of certain tumours. Objectives: The study was conducted to find out the occurrence of different tumours of skin in MGMCRI and to classify skin tumours (WHO classification). Methods: The pathological features of 52 cases of Skin Tumours were analysed between May 2009 and May 2014. Section of skin tissue was studied by light microscopy after hematoxylin and eosin staining. Results: A total number of 52 cases of skin tumours were studied. Benign skin tumours constituted 44.23% while malignant skin tumours constituted 55.76% of all skin tumours. Intradermal nevus was the most common benign Skin tumours while Squamous Cell Carcinoma was the most common malignant tumours. Conclusion: Light Microscopic examination remains the standard technique for the diagnosis of the tumours. Although special stain and immunochemistry can be utilised in situation where the diagnosis cannot be confirmed on hematoxylin and eosin. histopathological finding; gross anatomical, molecular finding and long term follow up


Introduction
Rudolph Virchow, the great pathologist more than a century ago considered skin to be a protective barrier for underlying viscera [1]. Considerable number of diseases can arise from the skin, as it is a complex organ [2]. Among all skin tumours, Keratinocytic tumours has significant impact on major health problem, although their mortality rate is comparatively low [3]. Malignant melanomas are important group of skin cancer, from a clinical point of view, although less common but more serious due to their high tendency to metastasis [4].
Cutaneous adnexal tumours describe as trouble some tumour by Cotton D [5]. Adnexal tumours are challenging to interpret because of its wide expanding list of entities, complicated nomenclature and the rarity of many of these tumours [6]. To give a meaningful clinical diagnosis, it is important to correlate the clinical differential diagnosis with the gross and microscopic  [7]. However, immunohistochemical and electron microscopic studies are required to study the histogenesis and final typing of the skin tumours [8]. The study was conducted to find out the occurrence of different tumours of skin in MGMCRI and to classify skin tumours (WHO classification). fixed in 10% formalin for 24 hrs and then four mm thick sections were cut from representative areas and submitted for routine processing. Section was studied by light microscopy after Haematoxylin and Eosin staining. The classification for the present study was based on the WHO classification of skin tumours (2005) [9].

Materials and Methods
Inclusion and exclusion criteria: Tumours and tumours like condition of epidermis along with melanocytic tumours and tumours of skin appendageal were included in thestudy. Patients who diagnosed as a Soft tissue tumour, Skin Secondaries and Haematolymphoid tumours were excluded from the study. The study was approved and permitted by Institutional Ethical Committee.
Statistical Methods: Data was entered in Microsoft excel sheet and analysed by using SPSS V. 16. Percentages and Chi-square value were calculated. P<0.05 was taken as significance.

Results
During the period of five years from May 2009 to 2014, there were 1256 cases of tumours were found. Out of which fifty-two cases were diagnosed as Skin Tumour which constitutes about 4.14% of all tumours. Out of fifty-two skin tumours, twenty-nine cases were malignant and twenty-three cases were benign.  Table 1]. In the present study squamous cell carcinoma found to be as most common malignant epidermal tumours. [ Figure:1]. Benign melanocytic tumours found to be most common benigntumours.Out of 9 cases of benign melanocytic tumours,3 cases ofintradermal nevuswere most common followed by 2 cases of congenital neuronevus [ Figure:2], 2 cases of compound naevus, one cases of junctional naevus and 1case of melanocytic naevus. In the study, epidermal tumour was commonest (72.41%) followed by Melanocytic (20.68%) and Adnexal (6.89%) [ Table 2]. Two cases of malignant proliferating Tricholemmal tumour was found[ Figure :3].

Discussion
Although in India the skin malignancies are rare compared to western countries. In India skin malignancies constitute about 1 to 2% of all cancers. The percentage of malignant tumours was relatively higher in study done by Sonam SK et al (2011) (65.29%) compared to present study (55.76%) which may be due to increase number of referral received in higher centre [10].  [13] study where basal cell carcinoma was 62% of all skin malignancy. We reported seven cases of Basal Cell Carcinoma, out of which one is pigmented variantand other wasbasosquamous variant of BCC. On histopathologically, we found island of hyperchromatic nuclei and scantycytoplasm with peripheral palisading arrangement, aretractionartifact separate the basaloid cells from the surrounding mucinous stroma.  [14,15].
In contrast with Sonam SK et al (2011) [10] study were Hair Follicle Tumour was found to be the commonest (52%) of all benign skin Appendeageal skin tumours and Sanjay N Parate et al found Basal Cell Epithelioma as most common (55%) among all Benign Skin Appendeageal tumours [8].
Proliferating Tricholemmal tumours was an extremely raremalignant tumour of follicular differentiation. Two cases of this tumour were reported in this study. Inthe study conducted by Paudyal P et al (2016) [17], showed 43 cases of Hair follicle tumours were benign. On histopathology tumour showed peripheral palisading of basaloid cells and large keratinocytes with eosinophilic cytoplasm and copious keratinization.
Intradermal nevus was the most common Benign Melanocytic Tumour in this study and similar observation was seen in Sonam SKet al (2011) [10] study.
The limitation of the study was for Special stain and immunohistochemistry can be utilized in situation where the diagnosis cannot be confirmed on Hematoxilin and eosin, such as typing of different adnexal tumours and melanoma. As molecular studies are not available in our set up, it was not possible to correlate histo-morphological findings with underlying genetic mutations leading to skin cancer.

Conclusion
Incidence of skin tumours constituted 4.14% of all tumours during five years period.It will highlight the rarity of this tumours. Most of the skin tumours are malignant with low incidence of benign tumour. It is always challenging to diagnose this tumours clinically. Histopathology is the gold standard to identify the architectural pattern of tumour and growth of infiltration to distinguish the malignant tumour. It is important to diagnose the malignant skin tumours due to its therapeutics and prognostic implications. The goal of improving diagnostic specificity will be achieved by detail histopathological finding; gross anatomical, molecular finding and long term follow up