2. Skin Pathology Flashcards
What cells (keratinocytes) are tough durable physical barrier, cells are attached to desmosomes, synthesize keratin, produce cytokines and defensins to regulate the cutaneous environment?
Squamous epithelial cells
Melanocytes produce melanin and protect from and screens UV light, langerhans cells are dendritic cells in the skin, process and present antigen to activate the adaptive immune system via migration to LN and present antigens to T cells, lymphocytes in the skin include CD4 CD8 and T reg cells, produce cytokines mediating the patterns and expression of inflammation and infectious disease. What nerves are responsible for physical sensations such as touch vibration pain itch cold and heat?
Afferent nerve fibers
*merkel cells are located in the epithelial basal layer without a known function
What are sweat glands which guard against variation of body temp and hair follicles which elaborate hair shafts with repositories for epithelial stem cells– they traverse epidermis and dermis?
Adnexal Skin components
Excoriation is linear, traumatic epidermal disruption often self induced. Lichenification is thick rough skin with prominent markings that can be due to repeated rubbing, oncholysis is separation of a nail from the underlying skin, a flat circumbscribed area are distinguised by coloration, what is it called when the falt lesion is less than or greater than 5mm?
less than 5mm is macule
greater than 5mm is patch
An elevated, dome shaped or flat topped lesions, if less than 5mm is a papule if greater than 5mm is a nodule, a plaque is an elevated flat topped lesions >5mm, may be caused by coalesced papules. Pustule is a discrete pus filled raised lesion, a scale is a dry horny plate like excrescence due to aberrant cornification, what is a pruritic elevated erythematous lesion with variable blanching, secondary to dermal edema?
Wheal**
Blisters have two types, fluid filled, raised lesions- vesicles are less than 5mm and bulla are greater than 5mm, acanthosis is diffuse epidermal hyperplasia, dyskeratosis is abnormal keratinization below the stratum granulosum, erosion is focal, incomplete discontinuous epidermal loss, what is infiltration of the epidermis by inflammatory cells?
Exocytosis
Hydropic swelling (ballooning) is intracellular keratinocyte edema often seen in viral infections, hypergranulosis is stratum granulosum hyperplasia usually due to rubbing, hyperkeratosis is stratum corneum thickening with abberant keratinization, lentiginous is linear non-nested melanocyte proliferation within the epidermal basal cell layer, what occurs when stratum corneum keratinization has retained nuclei- normally present on mucus membranes?
**parakeratosis
Papillomatosis is surface elevation due to dermal papillae hyperplasia, spongiosis is epidermal intercellular edema, ulceration is focal, complete epidermal loss reveals dermis or subdermis, vacuolization is vacuoles within or adjacent to keratinocytes, dysplatic nevus syndrome is related to a high risk of MM, what syndrome is associated with trichellomomas, and breast/endometrial and other cancers?
Cowden Syndrome
The 5 layers of the skin can be remembered by this mnemonic: Come, Lets Get Sun Burned - what are the layers?
Stratum Corneum Stratum Lucidum (only on soles of hands and feet) Stratum granulosum Stratum Spinosum Stratum Basale
What is the MC pigmented lesions of childhood in lightly pigmented individuals, 1-10mm, tan-red-brown macules, fade and recur depending of the amount of sun exposure, normal melanocyte density, hyperpigmentation due to focal melanin overproduction within basal keratinocytes (melanosomes)?
Freckles (ephelis)
There are major proteins formed within keratinocytes called keratins, which are intermediate filaments proteins making up the cytoskeleton of the cells, antibodies to various cytokeratins are used in pathology to identify keratinocytes. Maturation from basale to corneum is as follows: columnar to cuboidal to?
flattened
The epidermis is made of stratified squamous epithelium, the dermis is mainly connective tissue which contains blood vessels, nerves, and adnexa which is hair follicles, sebaceous gland and sweat glands (apocrine and eccrine), subcutaneous tissue mainly consists of ?
Fibrofatty tissues
NOTE: adnexa/appendages also include nails of toes and fingers
What is a common, benign, linear non-nested melanocytic hyperplasia in mucus membranes and skin, only in cell layer above BM- hyperpigmented basal cell layer, common in infancy and childhood, does not darken with sun exposure, hyperpigmented linear basal melanocyte hyperplasia, may see reet ridge elongation and thinning?
Lentigo (lentigines)
What is aka as a pigmented nevi or MOLE, common, congenital or acquired melanocyte neoplasms, most due to acquired activating mutations of RAS signaling*, more prominent during pregnancy indicated hormone sensitivity, rarely give rise to melanomas, p16/ink4a inhibits CDK4/6 = protective response?
Melanocytic Nevus
A junctional nevus occurs when there are nests of nevus cells at the dermoepidermal junctions, more common in kids and flat- most grow into the underlying dermis as nests or cords of cells to form compound nevi… What type of nevus is nests or cords of melanocytes extending into the underlying dermis (cells mature) becoming small and nonpigmented with fusiform contours and growing in fascicles, resembling neurological tissue = neurotization=b9? (note MM have no maturation)
Compound Nevus - both epidermal and dermal
intradermal nevus is completely dermis only
What nevus is a deep dermal subq growth around adnexa, neurovascular bundles and blood vessel walls, indentical to ordinary acquired nevi, present at birth, large variants = increase risk in MM?
Congenital Nevus
A blue nevus is a black blue nodule, non-nested dermal infiltration, often with assoc fibrosis, highly dendritic, heavily pigmented nevus cells, clinically may look like MM. What nevus has fascicular growth, fusiform cells, large plump cells with red pink blue cytoplasm, creates a red pink nodule, common in children, clinically confused with hemangioma?
Spindle and Epithelioid Cell nevus = SPITZ nevus
A halo nevus is identical to ordinary acquired nevi, lymphocytic infiltration surrounding nevus cells due to host immune repsonse against nevus cells and surrounding normal melanocytes, what nevus is described as coalescent intraepidermal nests, cytological atypia, potential marker or precursor of melanoma, may be direct precursors of MM when multiple in number are a marker of increased risk?
Dysplastic Nevus
Dysplastic Nevi are flat macules/slightly raised plaques with variable pigmentation and irregular borders in sun exposed and protected areas, most >5mm, may transform to MM may be direct precursor or increased risk, majority or stable and do not progress, due to loss of CDKN2A leading to CDK4 activation, NRAS and BRAF activation, TERT. Morphologically, what is characteristic in the dermis underlying atpical cells in a DN?
Linear or Lamellar fibrosis**
A DN can be a compound nevus with cytologic and architectural atypia, including irregular, angulated, nuclear contours with hyperchromasia, enlarged and fused (coalesced) nests of nevus cells, linear papillary dermal fibrosis is common due to melanin incontinence where melanin is lost and eaten by macrophages, what hyperplasia causes replacement of the basal cell layer along the dermoepidermal junction?
Lentiginous melanocyte hyperplasia
What syndrome is AD, develops multiple DN and MM are co inherited, develop multiple (hundreds), 50% have MM by age 60, due to loss of function of CDKN2A- different from typical melanocytic nevi- which encodes p16/ink4a (negative regulator of CDK4/6), most lesions dont progress- need more risk factors for cancer?
Dysplastic Nevus Syndrome
What is the most deadly of all skin cancers, cured if detected early and resected, strongly linked to UV radiation, most arise in skin, atypical melanocytes in nests and single cellular arrays at the dermal epidermal junction?
Malignant Melanoma
**worse and MC in men- cause men dont like drs duh
Cutaneous melanomas are due to UV damage causes DNA damage- UVB is the worst, risk includes severe sunburn in early life, lightly pigmented, fam hx mm, MC on back, arms, neck, legs, females back/legs, males upper back, morphology shows variations in color, on histo you see large cells with expanded, irregular what, containing peripherally clumped chromatin and prominent red nucleoli?
irregular Nuclei**
*stain with HMB-45
Radial growth of MM involves horizontal spread o MM in the epidermis and superficial dermis, unable to metastasize- 3 types include lentigo maligna, superficial spread is MC, and acral/mucosal lentiginous MM, what type of growth may occur after radial or horizontal growth, has met potential, tumor subclone with appearance of nodule, see dermal invasion of cells without maturation/neurotization, cells have met capabilities that increase as depth of invasion increases (breslow thickness)?
Vertical growth probability of metastasis correlates with depth of invasion • <1mm: 95-100% 5y survival • 1-2mm: 80-96% 5y survival • 2.1-4mm: 60-75% 5y survival • >4mm: 37-50% 5y survival
What is a benign epithelial tumor that is common spontaneous, arise on trunk most commonly, middle aged or older individuals, due to activating mutations in FGFR3, see a rounnd, flat coin like waxy plaque, sharply demarcated, uniform, tan brown velvety or granular round plaques see hyperplasia of pigmented basaloid cells and hyperkeratosis, keratin filled plugs may be seen along with keratin filled horn cysts, if irritated and inflamed basaloid cells undergo whirling foci of squamous differentiation?
Seborrheic keratosis SK
What sign is characterized by a sudden appearance of multiple seborrheic keratoses and paraneoplastic syndrome (usually GI cancer), due to keratinocyte stimulation via TGFa produced by tumor cells?
Leser Trelat Sign
What is a benign epithelial tumor characterized by hyperpigmentaed skin with a velvety texture seen in flexural areas, sign of underlying conditions, due to increased growth factor receptor signaling in the skin, 80% benign assoc with obesity or DM, pineal or pituitary tumor, if malignant assoc with GI adenocarcinomas- paraneoplastic phenomenon?
Acanthosis Nigricans
What is a benign epithelial tumor is very common cutaneous lesion, found on neck trunk face, sporadic, see soft flesh colored tumors w fibrovascular stalk, covered in benign epidermis, may cause pain by torsion, clinically usually inconsequential, may be assoc w DM, obesity or intestinal polyposis, increase in # during pregnancy due to hormonal stimulation?
Fibroepithelial polyp = acrochordon = skin tag
What cyst is invagination and cystic expansion of epidermis or a hair follicle, filled with keratinaceous material, common lesions, if large + trauma can spill keratin into the dermis and may lead to an extensive and painful granulomatous inflammatory response?
Epithelial or Follicular Inclusion Cyst = Wen = Sebaceous cyst = circumscribed with capsule*
The following are what kind of benign tumors… eccrine poroma, cylindroma, syringoma, sebaceous adenoma, pilomatricoma + hundreds more?
Adnexal appendage tumors
Note: syringoma has eccrine differentiation, usually multiple, small, tan papules near the lower eyelids
Ataxia telangiestasia is AR 11q22.3 mutation of ATM gene causing neurologic and vascular lesion, Cowden is AD 10q23 PTEN mutation leading to b9 follicular appendage tumors = trichilemmomas and internal adenocarcinoma, what familial syndrome is AD 9q22 PTCh mutation causing multiple basal cell carcinomas, medulloblastomas and jaw cysts?
Nevoid basal Cell carcinoma sydrome
What syndrome is AD 9p21 mutation of CDK2/p16/ink4 or CDKN2/p14/ARF which inhibits RB promoting cell cycle arrest/melanoma/pancreatic carcinoma, binds MDM2 promoting p53 function leading to melanoma and pancreatic carcinoma?
Familial melanoma syndrome
