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