Week 7 Histopathology Skin Flashcards
(37 cards)
What is this a picture of?
Psoriasis Note erythematous border, geographic shape and shiny, silver color (due to reflection of light from hyperkeratosis.
What is this?
Psoriasis The epidermis is thickened, when compared to normal skin. This is called acanthosis (black rectangle). The black arrows point to a band of small blue lymphocytes that seem to hug the dermal-epidermal junction. This is called a “lichenoid” infiltrate, because it reminded pathologists and dermatologists of moss (lichen) growing on a stone.
What is this?
Psoriasis
What is this and what is this characteristic of?
The focal inflamed areas in the epidermis have been called “Munro microabscesses”. They contain neutrophils, a few of which are denoted by the black arrows. Psoriasis
What is this and how do you know?
Most of the characteristic histologic features of pemphigus vulgaris can be seen at this power. There is formation of a bulla (blister), that occurs due to dissolution of epidermis, just above the basilar layer of cells (black arrows). This process is known as a suprabasal acantholysis
What is this and how do you know?
In permphigus vulgaris, recall that auto-antibodies of the IgG class are directed against desmoglien, a component of the desmosome. Anti-human IgG mouse antibody is incubated with the tissue, then rinsed off. This mouse antibody is tagged with a fluorescein molecule, which is bright green under UV light. This reveals a net-like pattern of IgG deposition between cells.
What is this and how do you know?
Bullous Pemphigoid even at low power, you should be able to tell that the epidermis has separated from the dermis, including the basal layer, in contrast to the previous case of pemphigus vulgaris.
What is this and what is it characteristic of?
Melanoma The tumor cells are polygonal or spindle-shaped, with abundant pink cytoplasm (blue arrow) and many are heavily loaded with fine dark-brown melanin granules (black arrow). Tumor cells are arranged in sheets and closely packed nests. The nuclei are pleiomorphic (vary in size and shape), and many are hyperchromatic and have prominent nucleoli. They fail to mature or disperse in their descent into the dermis.
What is the presumed cell of origin of this tumor? From what tissue is it derived embryologically?
This tumor begins in the epidermis, and is a result of melanocyte hyperplasia . This type of tumor is derived from neural crest cells.
What are the risk factors for melanoma?
About 10% to 15% of melanomas are inherited as an autosomal dominant trait with variable penetrance; as mentioned when discussing dysplastic nevi, some of these familial cases are associated with germline mutations affecting the genes that regulate cell-cycle progression or telomerase (described later). The overwhelming majority of melanoma is sporadic and is related to a single predisposing environmental factor: ultraviolet radiation (UVR) damage from sun exposure.
What are the most important predictors of prognosis?
One model used to predict outcome is based on the following variables: tumor depth (the Breslow thickness); number of mitoses; evidence of tumor regression (presumably due to the host immune response); ulceration of overlying skin; the presence and number of tumor infiltrating lymphocytes; gender; and location (central body or extremity).
What is this?
Thick Skin
What is this?
Thick Skin
What is the function of the stratum basale?
Sometimes considered the stem cells of the epidermis: mitose and progress up through the epidermis becoming more differentiated as it does so.
What do the spines in the spinous layer represent?
The spines are the shrinking of the microfilaments between desmosomes. The intercellular connections allow this layer to provide the superstructure of the epidermis.
What are the contents of the stratum granulosum?
1-3 layers of flattened polygonal cells with cytoplasm filled with basophilic granules. They contain keratohyalin granules.
What is the stratum lucidum?
The stratum lucidum is more apparent in thick skin and is a thin layer of extremely flattened, eosinophilic cells. Organelles and nuclei are not visible in this layer. It is present just below the stratum corneum.
Which cell biological processes occur in the stratum granulosum and corneum?
The stratum granulosum contains keratohyalin granules, which contain cysteine and histidine-rich proteins, the precursors for filaggrin. The stratum corneum has flattened, desicated, anucleate cells, which are the most differentiated cells in the skin. These cells are filled with keratin filaments. This forms the major consitituent of the water barrier in the epidermis. Stratum corneum is the layer that varies between the epidermis of thick and thin skin. This layer can become even thicker when friction occurs, giving rise to calluses.
What is the embryological origin of the epidermis? The dermis?
The epidermis is derived from the ectoderm and the dermis is derived from the mesoderm.
What is the embryological origin of melanocytes?
Melanocytes are derived from neural crest cells.
Are there more melanocytes present in pigmented skin?
No, the number of melanocytes is essentially equal in every race, but the type of melanin that is produced by the melanocytes differs.
What mode of secretion is used by sebaceous glands?
Holocrine
What is this?
Thin skin
What is this?
Sebaceous gland thin skin. Two kinds of glands subjacent to the epidermis can be observed. The sebaceous glands open into the hair follicles and are simple branched glands that exhibit holocrine secretion mechanisms. Note the light-staining secretory cells.
