02-13 Cutaneous Histology & Cell Biology Flashcards
1. Label the 4 layers of the normal epidermis, the 2 layers of the normal dermis, the basement membrane, and the panniculus. 2. List 3 characteristics of each of the following normal cells: keratinocytes, melanocytes, Langerhans cells, lymphocytes, eosinophils, neutrophils, mast cells, and histocytes/macrophages. 3. Describe the 3 types of glands normally found in the skin and describe the 3 elements of the normal pilosebaceous unit. 4. List 3 functions of normal vascular endothelial cells.
Layers of the skin?
- epidermis
- dermis
- subcutaneous fat
OBJECTIVE: List the layers of the normal epidermis
- Cell types?
- Stratum corneum
- (Stratum lucidum)
- Stratum granulosum
- Stratum spinosum
- Stratum basalis
All keratinocytes
Lateral connections between keratinocytes?
Adherent to each other via desmosomes (“intercellular bridges” or “prickles” or “spines”)
Pemphigous vugaris vs. bullous pemphigoid (which is here?)
- BULLOUS PEMPHIGOID on other side
- this is pem vulgaris
Dx? Etio?
Melasma, dark, irregular well-demarcated hyperpigmented macules to patches commonly found on upper cheek, nose, lips, upper lip, and forehead
- often develop gradually over time.
- no other symptoms beyond the cosmetic discoloration.
- common is particularly common in women, especially pregnant women and those who are taking oral or patch contraceptives or (HRT)
- also common in pre-menopausal women.
- thought to be enhanced by hormone surges in certain hormones.
Langerhans Cells
- Fxn
- Histo appearance
- EM appearance
- Appearance of malig transformation
- Primary APC of the skin
- Involved in allergic contact dermatitis
- Clear-staining cells in the suprabasilar epidermis
- Markedly folded nucleus, no desmosomes
- Contain a unique organelle: the Birbeck granule = a 3D, sphere-shaped w/ protruding rods
- tennis racket on EM
- Langerhans Cell Histiocytosis
- Kidney bean or sandal w/ neoplastic transformation (seen here)
What cells are these?
- Describe appearance
- Fxn?
Eosinophils
Appearance
- Slightly larger than neutrophils
- Bi-lobed (or _tri-_lobed) nucleus
- Granules of stain strongly eosinophilic (red)
Fxn
- Phag imm cmplxs and mast cell granules
- major roles in:
- anaphylactic reactions (Type I)
- hypersensitivity reactions (e.g. drugs or contact)
- parasitic infections
Dx? Tell me about it
Sweet’s Syndrome: neutrophilic dermatosis
- Sterile!
- para-neoplastic syndrome
A neutrophilic dermatosis is defined as a heavy dermal infiltrate of neutrophils where infection has been ruled out
Mast cells looks like
- Tell me more
fried eggs, [this is a MASTOCYTOSIS (neoplastic proilf of mast cells) here]
- Oval to spindle-shaped
- Concentrated around BVs
- many cytoplasmic granules (do not stain with hematoxylin-eosin) w/ serine proteases (tryptase and chymase) inside
- Stain with methylene blue, Giemsa, and Leder stains
- Degranulate after cross-linking with IgE on the cell surface
- Triggering degranulation can lead to anaphylaxis
Dx? Cell responsible for this?
Xanthoma, M0s that have digested lipids
Dx?
Sarcoidosis (sarcoid granules)
- vs. caseating necrosis of TB
Histiocytes and M0s
- Granuloma = quoi?
- “Histiocytes and macrophages are synonymous”
- Histiocytes (per wiki) = tissue M0s
- BM-derived precursors in blood = monos
- Differentiate into M0s with proper stimulation
- Make up the “mononuclear phagocytic system”
- Aggregates of activated macrophages are referred to as granulomas
What are these?
Eccrine (sweat) glands
3 types of skin glands?
- Mechanism of secretion
-
Apocrine* glands: mostly in odor-producing areas (e.g. axillary, anogenital regions), and the breasts, eyelids, and ear canals.
- Function unknown (other than to cause B.O.)
- *by membrane budding
- **Eccrine glands: **merocrine** sweat glands all over body
- for temp regulation (incl palms, soles)
- **excreted via exocytosis into lumen
-
Sebaceous glands: holocrine***, unilobular and multilobular, and secrete sebum
- ***secretions released by the rupture of PM, destroys cell → secretion into lumen
Hair follicle 101
- Three portions
- Sub-portions
- Follicle is associated w/ what other structures
Three portions:
- infundibulum (top of skin)
- isthmus
- lower - composed of 5 portions:
- Dermal hair papilla
- Hair matrix
- hair shaft (medulla, cortex and cuticle)
- Inner root sheath (inner root sheath cuticle, Huxley layer, Henle layer)
- Outer root sheath
-Associated with the arrector pili muscle (smooth muscle) and sebaceous glands
Weibel-Palade body
an electron-dense, rod-shaped structure in endothelial cells
- store and release: vWF and P-selectin
Name this structure. What is its fxn?
MEISSNER CORPUSCLE
- Mechanoreceptor responsible for sensitivity to light touch
Name this structure and its fxn
PACINIAN CORPUSCLE
- responsible for sensitivity to vibration and pressure
PANNICULUS = ?
subQ belly fat hanging down
Describe the cell types and organization of the dermis
COMPOSITION
- largely of C.T. (incl collagen and elastic fibers)
- Supports a vascular network, nerve fibers, the pilosebaceous system, and sweat glands
- underlaid by fat
- Cells: fibroblasts, histiocytes, and a few tissue mast cells and migratory blood cells.
- Superficial aspect appears as finger-like projections (papillae) supporting and nourishing the epidermis. Each papilla contains a capillary loop, lymph channel, and nerve fibrils supported in a connective tissue stroma.
ORGANIZED INTO TWO LAYERS
-
Papillary dermis: immediately beneath the epidermis send spikes up to nourish the epidermis
- primarily type III collagen
- more cellular than the reticular dermis
- separated from the deeper dermis by a horizontal BV plexus
-
Reticular dermis
- the bulk of the dermis; deep to the papillary dermis
- large bundles of type I collagen and elastic fibers
- BVs pass vertically through to connect subQ horizontal plexus with the horizontal subpapillary plexus
What nervous entity transmits the sensations of pain, itch, and temperature?
unmyelinated nerve endings in the papillary dermis
