Eyelids Flashcards
(31 cards)
What does the skin consist of
Epidermis, Dermis and Skin appendages
How are cutaneous tumors classified
By their cell of origin as well as their location in the epidermis, dermis of skin appendage
How are many layers are in the epidermis
Four
What cells does the epidermis consist of?
Keratinocytes, Langerhan cells, Melanocytes and Merkel cells
What are the layers of the epidermis and describe them
From superficial to deep:
Keratin (horny) layer - thin layer consisting of flat cells devoid of nuclei
Granular cell layer - one or 2 layers consisting of diamond shaped or flattened cells containing keratin hyaline granules
Stratum spinosum - 5 cell layers thick, polygonal in shape, have abundant eosinophilic cytoplasm. Free borders are joined by intercellular bridges (Desmosones) giving rise to the alternate name ‘prickle cell layer’
Basal cell layer - single row of columnar cells which give rise to more superficial cells. Contain melanin derived from adjacent melanocytes
What does the dermis consist of?
Connective tissue, blood vessels, lymphatics, nerve fibres, macrophages, fibroblasts and mast cells
How does the dermis and epidermis connect?
The upward dermal projections (papillae) interdigitate with the downward epidermal projections (rete ridges)
Where does the dermis lie in the eyelid?
On top of the orbicularis oculi
What are the skin appendages and where do they lie in the lid?
Adnexae
Lie deep in the dermis or within the tarsal plates
What glands are in the dermis and describe them
Sebaceous glands: located in the caruncle and eyebrow hairs. Tiny sebaceous glands are associated with thin (vellus) hairs covering periocular skin
Meibomian glands: Modified sebaceous glands within the tarsal plate that empty through a single row of about 30 openings in each lid. Each gland consists of a central duct and multiple acini, the cells of which synthesize lipid (sebum) which enters the duct and makes up the outer layer of the precorneal tear film
Glands of Zeiss: Modified sebaceous glands associated with lash follicles
Gland of Moll: Modified apocrine sweat glands that either open into a lash follicle or directly onto the anterior lid margin between the lashes. They are more numerous in the lower lid.
Eccrine sweat gland: Distributed throughout the eyelid skin, not confined to the lid margin unlike Gland of Moll
Pilosebaceous unit: Hair follicles together with their sebaceous glands
What is a macule
A localised area of colour change without elevation or infiltration. A macule may be pigmented (freckle), hypopigmented (vitiligo), or erythematous (capillary haemangioma)
What is a papule
A small solid elevation of skin that is either flat topped or dome shaped
What is a pustule
A collection of pus
What is a vesicle
A small circumscribed lesion filled with fluid
What is crust
Dried skin exudate
What is a nodule
A solid area of raised skin
What is a cyst
A nodule containing an epithelial lined cavity filled with fluid or semi solid material
What is a plaque
A palpable shallow elevation of skin, usually more than 2cm in diameter
What is scale
Thickening of the horny layer keratin in the form of readily detachable fragments
What is a papilloma
A tag like projection from the skin surface
What is an ulcer
A circumscribed lesion of skin loss extending from the epidermis into the dermis
What is hyperkeratosis
Increase in the thickness of the keratin layer seen clinically as scaly skin. Can be a feature of both benign and malignant epithelial tumors
What is acanthosis
Thickening of the squamous cell layer (stratum spinosum)
What is dysplasia
Alteration in the size, morphology and organisation of cell structures. There is disturbance of normally structured and recognised layers of tissue e.g. loss of cell polarity
