Haematoxylin and Eosin Stained Human Tissue - Term Paper Example

Histopathological Practical Report Name: Partner’s Name: Practical Group Session: Introduction This practical session involved the examination and drawing of sections of Haematoxylin and Eosin stained human tissue obtained from normal and healthy state, and also from diseased state. Histopathology is the study and microscopic examination of a diseased biological tissue in finer details by a pathologist. The study specimens require tissue preparation and treatment in the pathology laboratory before analysis is carried out using techniques appropriate to the investigations required and the type of the tissue under studyi. The processed specimens and histological sections are placed on the glass slides for microscopic examination. Histopathology is important in clinical medicine, where it involves examination of a surgically removed specimen or a sample taken from a patient for detailed study; also referred to as a biopsy. After the specimens are have been observed, a range of scientific techniques may be used to discover the presence of a disease, and subsequently, the most appropriate action that need to be taken. In conducting this experiment, we hoped to discover the difference in tissue structures between a normal human skin and a diseased human skin as observed under a microscope. Aims This practical experiment was carried out with two main aims. The first aim was to examine and draw sections of a normal human skin tissues and a diseased tissues. The second aim was to describe the characteristics of the diseased tissues in relation to the tissue structures examined under the microscope. Methods Pre-prepared sample slides of normal and abnormal human skin tissues stained with Haematoxylin and Eosin (H & E) staining method were provided in the pathology lab. The abnormal tissues were associated with malignant melanoma Squamous cell carcinoma. The sample slides were then examined in detail in three stages, starting with the normal tissues specimen, followed by the diseased tissue samples. The first observation stage involved examination of the specimen using a naked eye to note physical information and other structures that can be observed by naked eye. In the second stage, the samples were examined under low power (40x magnification), before examining them under high power (400x magnification) for a more detailed view in the third stage of examination. Identification of normal structures of the tissues was aided by use of an atlas of normal histology, while in identifying diseases, histopathology texts were used. After examination of the tissues under low power and high power, the tissues were presented in two diagrams; low power diagram and a more detailed high power diagram. This diagrams were used to describe the histology, and normal organization of structures and their functions in normal skin tissues. Results and Discussion (a) Normal human Basal cell carcinoma Histology of the normal human skin In each examination of the specimen, a diagram of the tissue as observed under the microscope were drawn. In figure 1 and 2 below, diagrams of normal human skin tissues have been presented as observed under low power and high power microscope. Figure 1: Transverse section of a normal human skin. The specimen showed pink cells with nucleus. The hypodermis was colorless with less connective tissue (H&E, low power X40). In reference to figure 1 above, the overall structure of the normal skin tissue, such as tissue layers and how they are arranged can be noted. The histological structure of the skin in figure 2 shows three main layers; the epidermis, the dermis (reticular layer) and the hypodermis (subcutaneous). The epidermis is the outer superficial layer and it consists of stratified squamous epithelium and epidermal ridges. It does not contain blood vessels, and obtains its nutrition by diffusion. There are three types of cells that make up the epidermis; Keratinocytes – which form keratin, dendertic cells – form melanin from melanocytes, and Langerhans' cells act as microphages, and lastly, Merkel cells – which act as receptors for touch. The epidermis play a vital role in protecting the inner layers of the skin. The dermis consists of the papillary layer and the reticular layer. It acts as a supporting framework for lymphatics, nerves, blood vessels, hair follicles, sebaceous glands, and sweat glands. The blood vessels supply the required nutrients to the avascular epidermis. Mostly, the dermis contains fibroblasts which secrete elastin, collagen and a ground substance that provides elasticity and support to the skin. It also contains immune cells that protect the inner tissues from foreign invaders that may pass through the epidermis. A papillary layer, formed of loose connective tissue with collagenous, elastic and reticular fibers, lies beneath dermis. The papillary layer contains sensory nerve endings other structures known as Meissner’s corpuscles in areas that are highly sensitive. The basal lamina is made of highly cross-linked extracellular matrix consisting of a mixture of collagens, perlecan, laminin and entactin proteins. It provides support to the epithelium, and limits contact that may occur between epithelial cells and other types of cells in the tissue. The hypodermis is a fatty layer that contains adipose tissue. It contains loose connective tissue, elastin, and adipose tissue. The hypodermis lies below the dermis, and does not form part of the skin. Its main function is to attach underlying bone and muscle to the skin, and supply the skin with nerves and blood vessels. Adipocytes, fibroblasts, and macrophages are the main cell types found in the hypodermis. Almost 50% of body fat is found in the hypodermis layer and it serves as insulation and padding for the body. In figure 2 below, a more detailed diagram of the normal skin under a higher magnification is shown. The diagram show finer details of the skin as observed with a microscope at X400. Structures that can be seen include hair follicle, glands, Stratum corneum, Stratum spinosum, and Stratum basale or stratum germinativum. Figure 2: Transverse section of a normal human skin. The specimen showed a pink tissue with a purple nucleus. (H&E, high power X400). The hair follicle is an organ that produces various kinds of hair. The physical role of the hair on the human body is control body temperature, enhancing sensation, and providing protection. The follicle also contains some stem cells that can regrow to replace worn out epidermal cells. There are two types of glands found in the human skin; sebaceous glands and sweat glands. The sebaceous glands secrete a substance called sebum into the follicles. It is an oily substance that moistens and softens the skin, and keeps it from foreign materials. The sweat glands release sweat in case of heat and stress to cool the body The Stratum corneum, Stratum spinosum, and Stratum basale are epidermal sub-layers. The stratum corneum forms the outermost epidermal layer as can be seen in figure 2 above. It consists of corneocytes (dead cells) with no nuclei or cell organles. It contains three lipid components; cholesterol, ceramides and fatty acids. The main function of the stratum corneum is to protect the underlying tissues from dehydration, chemicals, infection, mechanical stress, and other foreign substances by forming a barrier. The stratum spinosum is found between stratum corneum and stratum basale, appearing spiny due to shrinking of microfilaments found between desmosomes as a result of staining with H&E. It is in the stratum spinosum where keratinization begins to form tonofibrils, which go on to form desmosomes. The desmosomes allow for strong connections between keratinocytes. The stratum basale is the deepest layer made of a 1 to 3 cells thick. It is mainly made of keratinocyte stem cells, which divide to form keratinocytes found in the stratum spinosum and later migrate superficially. Melanocytes, Langerhans cells and Merkel cells are the other types of cells in the stratum basaleii. (b) Skin Diseases (Skin Cancers) i. Squamous cell carcinoma (SCC) Figure 2 and 3 below show s diagrams for low power and high power magnification of a skin effected by SCC. Figure 3: Cross section of squamous cell carcinoma (SCC). Epithelial cells show glassy eosinophilic cytoplasm with a large nucleus. Horn pearl formations can also be seen. (Low power, x40) Location of the SCCs Referring to figure 4, the carcinoma is located in a layer of keratinocyte cells situated in the epidermis. The diagram shows proliferation of anastomosing strands and nests originating from the epidermis. The diseased tissue appears different from the normal tissue because of the abnormal growth of cells in the squamous cells found in the dermis. This occurs as a result of keratinization of the cells in the epidermal layer to form a keratinous pearl that is seen in figure 4 below. Figure 4: High power (x400) cross-section diagram of SCC. Tumor cells are transformed into keratinized squames around nodules characterized by concentric, nested layers or keratinous pearls. Presentation, appearance, clinical features, risk factors, and prognosis and treatment of SCCs. Squamous cell carcinoma normally presents in a patient as a crusted or indurated nodular keratinizing tumor that appears ulcerated or sometimes, it may present itself as ulcer, but lacks evidence of keratinization. It appears as a growth or an ulcer that is non-healing especially in areas that have a higher risk of sun exposure. Most SCCs are seen on the skin around the neck or head. Its clinical features may vary: it may appear as reddish skin plaque or as slow-growing ulcer; or a small nodule may become bigger with a necrotic center, and develops into an ulcer. Thus, the tumor typically presents itself as an ulcerated lesion characterized with hard and raised edges. Sometimes, bleeding may be observed from the tumor. Squamous cell carcinoma can arise to spreading to lymph nodes or local metastases. Risk factors for SCC include: excessive exposure to UV, fair skin, use of indoor tanning beds, history of skin cancer, sunburns, or precancerous skin lesions, genetic disorder, and weakened immune systemiii. SCC tends to develop on the sun exposed areas after many years of exposure. The condition is common in parts, such as the neck, head, hands or lower legs. It can also spread to the lips, inside the mouth or genitals. Use of tanning beds increases the risk of getting SCC. If diagnosed early in life, this condition can be cured in a number of ways, including; excision, urettage and electrodessication, cryosurgery, photodynamic therapy, medicine with imiquimod or 5-fluorouracil, Mohs surgery, or by radiation. ii. Malignant melanoma Malignant melanoma is a neoplasm of cells developing from melanocyte cells in the skin, and is currently the most threatening cancer of the skin. The condition starts by growing on the skin, and if undetected, it can spread to the lymphatic system and blood vessels. It can be very fatal if it spreads to other parts of the body. The diagram for malignant melanoma are presented in figure 5 and 6 below. From the diagrams, the malignant melanoma is located at the junction of the epidermis and the dermis and appears as clusters of cells invading the dermis, making this tissue look different from the normal one. Figure 5: Malignant melanoma showing the melanocytes invading into the boundary between the epidermis and papillary dermis, either as single cells or nests. (H&E, Low power, 40x). Figure 6: Malignant melanoma showing dermal invasion (H&E, High power x400). Presentation, Clinical features, Risk factors, Prognosis and treatment of malignant melanoma Metastatic melanoma can result to non-specific para-neoplastic symptoms, such as fatigue, vomiting, nausea, and loss of appetite. It is possible to have metastasis of early stage melanoma, although it is very rare. Brain metises are most common in people with metastatic melanoma, and sometimes, it can spread to the bones, abdomen, liver or lymph nodesiv. Clinical features of malignant melanoma include changes to the color or shape of existing moles. For nodular melanoma, a new lump may appear anywhere on the skin. If the disease is in its later stages, then the mole may ulcerate, itch or bleed. The early signs of the disease are summarized under the mnemonic ABCDE, which stand for: A – Asymmetry B – Borders (irregular – corners & edges) C – Color (variegated) D – Diameter (>6mm) E - Evolving over time There are a number of risk factors associated with malignant melanoma for people who have the following: compromised immune system; many moles (>50); sun –sensitive skin that is likely to burn instead of tanning; large moles or moles that have unusual shape or color; family history of the disease; excessive UV exposure; or a history of extreme sun-burns. If an individual has several of the aforementioned risk factors, then the risk of malignant melanoma is multiplied. One can also get melanoma if they have no these risk factors, but they have darker skinv. Malanoma starts with cells that form the pigment melanin. The condition starts with the growth of a dark mole on the skin. Early detection of the malignant melanoma increases the chances of patient survival. The first step on detection of melanoma is surgical excision of the whole lesion. For delayed detection, other treatment options such as chemotherapy, immunotherapy, biological therapy, and radiation therapy are available. iii. Basal cell carcinoma (BCC) Figure 7 and 8 show a presentation of the low power and high power BCC specimens as viewed under the microscope. Figure 7: BCC arising from the basal layer of the skin in the epidermis. Nuclear palisading and apoptosis is also observed (Low power, x40). In reference to the figure 7 and 8, it is observed that BCC grows in the basal cells situated in the dermis layer, away from the epidermis. The specimens show tumor cells forming irregular tumor nests which are separated with reduced stroma. This explains why the diseased tissue is different from the normal tissue. Figure 8: BCC showing superficial growth of clusters of tumor cells. (High power, x400). Presentation, Clinical features, and Prognosis and treatment of BCC Patients with BCC report enlarging lesion that is not easily healed or bleeds. As tumors likely occur on a patient’s face, they often report acne bump that bleeds at times. Clinical features of BCC include ulcerated epidermis, basaloid tumor cells growing from follicles or epidermis, peripheral palisading of nuclei, and mucinous stoma. Treatment of BCC can involve either surgical or non-surgical techniquesvi. Surgical techniques include; excision, Mohs micrographic surgery, electrodessication, cryosurgery, radiotherapy, and topical photodynamic therapy. The recurrent rate of this condition is variant depending on the technique employed to treat it. Except for Moh’s surgery, all the other techniques listed above have a recurrent rate of >10%. Patients should avoid exposure to the sun, and have regular skin check-ups.vii References Read More