CM- Cutaneous Neoplasia Flashcards
What are the four types of cells that make up the epidermis?
- keratinocytes
- melanocytes
- Langerhans cells
- Merkel cells
What is the structure of a keratinocyte?
Describe the cytoplasm, nuclei, and relationship to other cells.
- Eosinophilic cytoplasm
- vesicular nuclei
- closely opposed cells with intercellular bridges between cells
What is the function of keratinocytes?
epidermal barrier [provide protective covering]
What are the 4 layers of keratinocytes from most superficial to deepest?
Describe the histology of each layer.
- Stratum corneum [“cornified layer”]
- flat, anucleate, eosinophilic cells - Stratum granulosum [“granular layer”]
- basophilic granules with proteins to make epidermal barrier - Stratum spinosum [“spinous layer”]
- prominent intercellular bridges
- several layers thick - Stratum basale [“basal layer”]
- single layer, cuboidal to columnar cells
- more basophilic than keratinocytes in upper layers
You are looking at histology of the epidermis and see cuboidal cells with clear cytoplasm and eccentric nuclei.
These cells are basally located.
What cell is this? What is the ratio of this cell to basal keratinocytes?
Melanocyte
Ratio is 1:4 to 1:9
How does the number of melanocytes vary by race?
What is the function of these cells?
All races have the same # of melanocytes, but the races vary on how much pigment is made in melanosomes.
Function of melanocytes = produce protective pigment
You are looking at histology and see cuboidal cells with clear cytoplasm and eccentric nuclei in the middle of the spinous layer of epidermis.
What cell is this and what is the function?
Langerhan’s cells - macrophage like cell derived from the bone marrow.
Function: present antigens, be involved in cutaneous immunity
What is the structure of a Merkel cell?
What is the function?
Merkel cells are hard to identify on H&E but they are similar to neuroendocrine cells.
Function: sensory perception
What is the function of the epidermal-dermal junction?
What are the ultrastructural and biochemical components from superficial to deep?
It is important for providing structural integrity to the skin.
- basal keratinocytes with hemidesmosomes to anchor to the BM
- BM
- lamina lucida with anchoring filaments
- lamina densa with type 4 collagen - Sublamina densa with anchoring fibrils [type 7 collagen]
What is the difference between papillary and reticular dermis?
Papillary dermis- eosinophilic, tightly packed collagen bundles that extend up between epidermal rete ridges
Reticular dermis- loosely packed larger collagen bundles
What are the 3 ECM components of the dermis?
- collagen bundles
- elastic fibers
- glycosaminoglycans [GAGs] aka ground substance aka dermal mucin
What are the 3 cellular components of the dermis?
- fibroblasts
- synthesize collagen, elastin, proteoglycans
- spindle-shaped with dark small nuclei - dermal dendrocytes
- APCs
- difficult to see on H&E - Inflammatory cells
- low in number for healthy skin
- macrophages, mast cells [histamine], lymphocytes [80T,20B]
What 2 inflammatory cells are only seen in abnormal skin?
- eosinophils
2. neutrophils
Describe the blood supply located in the dermis.
- Arteries are in the transverse septum of subcutaneous fat and form DEEP PLEXUS in reticular dermis
- Arterioles pass into the papillary dermis and form SUPERFICIAL PLEXUS
- capillary-venules form superficial vascular loops which ascend and descend the papillary dermis
Describe the histology of the following structures in the dermis:
- vessels
- lymphatics
- basophilic, flat endothelial cells and pericytes surrounding lumen containing RBCs
- basophilic flat endothelial cells with FEWER pericytes and NO RBCs in the lumen
What is the glomus?
where is it located?
What is the function?
It is a vascular structure in the reticular dermis of:
- pads of digits
- nailbeds
- face
- ears
That regulates temperature via AV shunt
Where in the skin are the following located and what do they look like?
- schwann cell
- Meissner cell
- Vater-Pacini cell
- dermis; S shape, with wavy nuclei and pale cytoplasm
- dermal papillae; hard to see on H&E
- subcutaneous fat; onion-like shape
How histologically can you identify non-vascular smooth muscle in skin?
what are the 2 locations where this smooth muscle is found?
Absence of striation and centrally-located nucleus
- arrector pili muscles - erect hair shaft
- nipples and scrotum - extra smooth muscle bundles`
What are the 4 “epidermal appendages” found in the dermis?
- folliculosebaceous unit
- eccrine glands
- apocrine glands
- nail unit [matrix, bed, plate]
Where are folliculosebaceous units found?
What are the 2 components?
All cutaneous sites except glabrous [hairless] skin like the palms and soles.
- follicle = cylidrical downgrowth of surface epithelium surrounded by connective tissue
- sebaceous gland = one to several lobules that lead to a common excretory docut composed of stratified squamous epithelium
Describe the 3 parts of a hair follicle.
- infundibulum = opens to the surface
- isthmus = small portion from insertion of arrector pili to entrance of sebaceous duct
- inferior portion = hair bulb and germinating epithelium
Describe the structure of the sebaceous gland.
one to several lobules leading to a common excretory duct.
- Lobule:
- peripheral cuboidal, basophilic cells
- central lipid-containing, clear cytoplasm, delicate pink strands - excretory duct
- stratified squamous epithelium
What are eccrine glands?
where are they located?
What is the histology?
True sweat glands located everywhere except:
- external auditory canal
- lips
- labia minora, clitoris
Composed of:
- Cuboidal cells with clear, glycogen containing cytoplasm
- darkly staining myoepithelial cells
What is the acrosyringium?
The part of the eccrine gland duct that courses through the epidermis.
Where are apocrine glands located?
eyelids
external ear
axillae
anogenital region
What are the 2 major components of subcutaneous tissue [panniculus adiposus]?
- lobules of mature adipose tissue
- adipocytes with clear cells with displaced nucleus - fibrous septa-think fibrovascular tissue surrounding individual fat lobules
- fibroblasts, collagen
- vessels
- nerves
Describe variations in epidermal thickness by body region.
- Thin [few cell layers thick] = eyelids, genitalia
- Medium = trunk, extremities
- Thick = palms and soles [with compact cornified layer]
Describe variation in hair follicles by body region.
- Scalp = long follicles that extend into fat
- Face = shorter follicles with larger sebaceous glands
- palms, soles = no hair follicles
What areas of the body lack stratum corneum?
mucousal surfaces
A lesion of the skin:
- remains small or grows slowly
- symmetric, well circumscribed, can be “shelled out”
- VERTICALLY oriented
- peripheral fibrous tissue is dense
- clefts between lesion’s stroma and normal dermis
- localized [either superficial OR deep]
- does not ulcerate unless traumatized
- uniform size/shape nests of cells with smooth borders
- neoplastic cells in discrete arrangements
- epithelial cells are NOT in single file line between collagen bundles
- well-differentiated cells
- adnexal structures are preserved.
- necrosis of single cells, but NONE en masse
- no neoplastic cells in nerves or vasculature.
Benign or malignant?
Benign
How does the melanocyte differ from a benign nevus to a melanoma?
Benign nevus:
Melanocyte nuclei at the base of nevus is much smaller than those near the surface [maturation]
Melanoma:
Maturation is not seen
How do clefts differ between benign and malignant skin neoplasms?
Benign:
cleft between lesion’s stroma and normal dermis
Malignant:
cleft between neoplastic cells and lesions stroma
How does vertical/horizontal orientation differ between malignant and benign skin neoplasms?
Benign - vertically oriented and can be shelled out
Malignant - horizontally oriented
After you use a constellation of criteria to determine benign v. malignant, what is the next step in identifying the neoplasm?
Pin down the specific cellular differentiation:
- epithelial cell:
- squamous, follicular, sebaceous, apocrine, eccrine, melanocytic
- ALL are + for cytokeratin except melanocytic - non-epithelial
- lymphocytes, mast cells, histiocytes
- neural, muscular, vascular, fibrous, adipose differentiation
What is the cellular differentiation that causes actinic keratosis, Bowen’s disease and squamous cell carcinoma?
Epithelium - spinous cell layer
Histology shows thickened epidermis with downward proliferation of keratinocytes that are disordered near the bottom layers [some are anaplastic with large irregular nuclei].
Overlying hyperkeratosis and parakaratosis.
What is this called?
What is it a precursor for?
Actinic keratosis which is a precursor for SCC.
Histology shows thickened epidermis with the ENTIRE epidermis consisting of disordered, anaplastic keratinocytes. What is this called?
Bowen’s disease [SCC in situ]
Histology shows nests of irregular, anaplastic keratinocytes proliferating downward into the dermis.
Horn pearls [centers of compact keratin with retained nuclei] are present.
there is overlying hyperkeratosis and parakeratosis.
What is the diagnosis?
SCC
Histology shows basaloid neoplastic cells extending from under surface of the epidermis. The cells are growing horizontally/radially and involve the lower epidermis/upper dermis. What is the diagnosis?
Superficial Basal cell carcinoma
Histology shows infiltrative nests of basal keratinocytes [cuboidal, columnar with oval nuclei and less pink cytoplasm].
there are peripheral palisading basal cells at the edge of the nest.
There is clefts between the tumor nests and myxoid stroma.
What is the diagnosis?
Nodular basal cell carcinoma
How do melanocytic nevi cells differe from melanocytes?
They are basically identical except nevi cells are arranged atleast partially in nests and clusters.
How do melanocytes change in appearance the deeper into the dermis they get?
Melanocytes are usually cuboidal cells with pink cytoplasm and vesicular nuclei.
Deeper into the dermis = less cytoplasm, darker nuclei
What are the 3 types of nevus?
- junctional = melanocytes confined to epidermal-dermal junction
- intradermal = melanocytes confined to dermis
- compound= junction and dermis
Histology shows single melanocytes and nests of varying size at the epidermal-dermal junction.
Melanocytes also ascend to higher layers of the epidermis.
Nests coalesce to form sheets in the dermis.
There is exuberant inflammatory infiltrate and mitotic figures.
the lesion is asymmetric and not well-circumscribed.
What is the diagnosis?
Melanoma
Describe melanoma in situ.
Normally melanocytes reside at the epidermal-dermal junction.
In situ melanoma:
- broad, asymmetric, poorly circumscribed lesion
-neoplasm in every layer of the epidermis
What is Brewslow depth?
vertical distance in mm from granular layer to deepest melanoma cell in the subepidermal tissue.
Melanoma less than 0.76mm has not yet metastasized.
