Dermatology Flashcards
Inheritance of Marfan syndrome
Autosomal Dominant
What is defective in Marfan syndrome?
Protein called fibrillin
*Located in ECM
Autoantibodies to adhesion proteins (ie: desmosomal or hemidesmosomal) can lead to what 2 diseases, respectively?
Desmosomal autoantibody:
Pemphigus vulgaris
Hemidesmosomal autoantibody:
Bullous pemphigoid
Another name for atopic dermatitis
Eczema
Eczema is considered which hypersensitive reaction/
Type 1
*Treat with topical steroids
Microscopy analysis of atopic dermatitis would show what?
Spongiosis (increasing spacing of epidermal cells due to intercellular edema)
What is the difference in location of the erythematous lesions in infants vs children/adults who are affected by eczema?
Infants: Extensors
Adults: Flexors
What can be in the family history of a patient who has eczema?
Family has hay fever, allergic rhinitis, or asthma
What type of sensitivity reaction is contact dermatitis?
Type 4
Cause of lichen simplex chronicus?
Itching & scratching
*Results in leathery thick skin
Differentiating factor between eczema & seborrheic dermatitis?
Seborrheic dermatitis is confined to head & scalp with red patchy infiltrate
Explain how restoration naturally of the epidermis can occur?
Stem cells located in the hair follicles and sweat glands within the dermis
**Because items above are derived from ectoderm too, which includes hair follicles, sebaceous glands, & sweat glands
***Dermis is derived from mesoderm
Where are melanocytes derived from embryonically?
Neural crest cells
Inheritance of xeroderma pigmentosum
Autosomal recessive
Characteristic of xeroderma pigmentosum
Extreme sensitivity to sunlight
*predisposition to malignancy –> malignant melanoma, BCC, & SCC
Reason for xeroderma pigmentosum
Defective nucleotide excision repair (NER) mechanism of UV damaged DNA, causing pyridimidine dimers
*Thymidine nucleotides form covalent bonds with each other rather than complementary bases on opposite DNA strand
**These mutations accumulate and can cause cancer
Explain the ABCDE rule and what is it used to identify?
Melanoma
- Asymmetry of growth
- Borders are irregular
- Color variations
- Diameter great than 6 mm
- Evolution over time
What is the name of the ulcerative form of impetigo?
Ecthyma
2 main forms of impetigo
1) Non-bullous [either S. aureus or S. pyogenes]
- Lesions begin as papules & progress to vesicles
- Later become pustules
2) Bullous [only S. aureus]
- Caused by exfoliative toxin A
What is + Nikolsky sign suggestive of? What is it?
Rubbing results in skin exfoliation
Dx: Pemphigus Vulgaris (autoimmune disease)
*Caused by dysfunctional desmosomes in epidermis
What disease is associated with a defect in actin?
NONE! trick question….not a single one exists
Inflammation of the nasolacrimal sac & cause?
Dacryocystitis
*Due to obstruction of nasolacrimal duct, causing reduced tear flow & infection
Infant who develops generalized severe erythema and flaccid bull (+ Nikolsky sign) is indicative of what infection?
Scalded skin syndrome
*S. aureus
**Treat baby like burn victim
In scalded skin syndrome of the infant, where are symptoms especially located?
Around the umbilicus
What do exotoxins in staph infections typically target in scalded skin syndrome?
Desmosomes between keratinocytes in the stratum granulosum
What diseases demonstrate a + Nikolsky sign? (3)
- Scalded skin syndrome
- Epidermal necrolysis
- Pemphigus vulgaris
Maculopapular rash that begins in the face and neck, traveling to the extremities, and sparing the palms & soles is what disease?
Scarlet fever
*S. Pyogenes
What is the severe cause of Steven-Johnson syndrome?
Toxic epidermal necrolysis
*Presents similar to scalded skin syndrome but patients are older, involve mucous membranes, and triggered by new medicines
Vitamin C is an essential cofactor for what in scurvy?
Necessary for hydroxylation of proline & lysine residues on pre-pro-collagen chains
Cause of albinism
Deficiency in enzyme tyrosinase (AR inheritance)
*Inability to synthesize melanin from tyrosine (aromatic amino acid)
Function of hemidesmosomes
Connect basal surface of epithelial cells to underlying basement membrane
In which layer are blisters formed in bullous pemphigoid?
Subepidermal
What are antibodies being made against in the disease involving hemidesmosomes?
Dystonin
*Bullous pemphigoid
Function of the desmosome
Connecting the lateral surfaces of two adjacent cells together
Where are blisters located in pemphigus vulgaris
Intraepidermal
Most common cause of erythema multiforme
Herpes simplex virus
*this rash has a target lesion
**Due to CD8 & CD4 cells targeting epithelial cells
What are 2 diseases/conditions that can cause a rash on the palms & feet?
1) Erythema muliforme
2) Syphillus
Triggers of erythema multiforme
- MEDICATIONS: penicillin, sulfonamides, allopurinol
- INFECTIONS: HSV 1 or 2; mycoplasma pneumoniae
Describe papule found in molluscum-contagiosum virus
Flesh-colored, dome-shaped papules with central depression (called umbilication)
*Caused by pox virus
Where does smallpox typically begin?
Rash that begins on the face and progresses to the arms, legs, hands and feet
*Vesicular or pustular lesions
Cause of athletes foot
Tinea pedis
What would be the defining factor for a carcinoma of the skin to be in situ versus invasive?
*Invasive = disruption of the basement membrane, involvement of the dermis, and possible invasion of lymph & blood vessels
*In situ = abnormal keratinocytes extending throughout the full thickness of the epidermis without disruption of the basement membrane
What is squamous cell carcinoma derived from & which layer of epithelium?
Keratinocytes in the epidermis (stratum spinosum)
What are premalignant lesions of SCC referred to as? What would they appear as clinically?
Actinic keratosis
*Associated with hyperkeratosis
**Clinically, tan-brown-red color with rough, sandpaper-like consistency & cutaneous horn formation
If a patient presents with a port-wine stain, what should they be evaluated for?
Sturge-Weber disease
*Slowly progressing neurocutaneous disorder
When biopsied, what would a port-wine stain appear like?
Capillary malformations
Characteristics of Sturge-Weber disease (5)
1) Leukocoria (absent red-reflex)
2) Ipsilateral leptominingeal angiomatosis
3) intellectual disability
4) Seizures
5) Pheocromocytoma
What causes scabies?
Sarcoptes Scabiei mite
Signs of scabies infection
- Intense pruritis
- Burrow skin lesions over wrists, finger webs, genitals
Hypertrophic scars are due to up regulation of what protein?
TGF-beta
*Controls fibroblast recruitment & collagen deposition
What layer of the skin are warts typically found to originate in?
Stratum granulosum
*Due to multiple dense basophilic keratohyalin granules containing lipids to help form a waterproof barrier
What layer of the skin is responsible for waterproofing
Stratum granulosum
*Due to multiple dense basophilic keratohyalin granules containing lipids to help form a waterproof barrier
Where in the body would we find naturally a thicker layer of stratum lucidum?
Palms & soles of feet
What layer of skin do squamous cell carcinomas develop in?
Stratum spinosum
What layer of skin does pemphigus vulgarisms develop in?
Stratum spinosum
What is the most prognostic factor in determining malignancy of melanoma?
DEPTH (not diameter!!)
What would melanoma stain + for and what is its marker?
S-100 (stain) & HMB45 (melanoma marker)
Why is depth the most important prognostic factor for melanoma?
Because the lymphatics of the superficial dermis lie only 1 mm under the skin surface
Biopsy of a suspected lupus rash would show what?
IgG deposition & compliment at the derma-epidermal junction
What is the technical term for the butterfly rash seen in lupus?
Malar rash
What is the difference in antibodies between limited & systemic sclerosis?
LIMITED:
Increased anti-centromere antibody
SYSTEMIC:
Increased anti-Scl-70 (DNA topoisomerase 1) antibody
What is the pathomechanism of wheal formation?
Mast cell degranulation causing dilation of superficial lymphatic channels & intradermal edema (causing spongiosis)
Microabscesses in the stratum corneum can be seen in what diseases (4)
1) Impetigo
2) Fungal skin infections
3) Psoriasis
4) Cutaneous T cell lymphoma
Microscopic blisters at the tips of dermal papillae is characteristic of what?
Dermatitis herpetiformis (celiac disease)
What is acanthosis?
Stratum spinousum proliferation
*Seen in acanthosis ingrains
What is parakeratosis?
Retaining nuclei in the stratum corneum
Acanthuses nigrans can be suggestive of what?
- Underlying cancer (diffuse gastric carcinoma)
- Obese patients
- Diabetic (type 2) patients
What visible changes would you see to suggest a patient has stasis dermatitis?
- Hyperpigmentation of skin
- Erythematous skin ulcerations in legs
- Chronic edema
How does PAD look differently than venous stasis visually?
PAD ulcers usually occur at the tips of digits where distal arterial branches are located
*diabetic ulcers present at foot pressure points
Which are painful and which are painless; arterial & venous ulcers
Arterial: PAINFUL
- Due to ischemia
- Ulcers at tips of toes/bony prominences (lateral malleolus & metatarsal heads)
Venous: PAINLESS
What is the precursor lesion called of squamous cell carcinoma?
Actinic keratosis
*hyperplastic lesion
What is the typical presentation of squamous cell carcinoma?
Scaly, red plaque with ulceration & bleeding
Histology of squamous cell carcinoma
- Keratin pearls
- Large & hyperchromatic nuclei
Risk factors of SCC (excluding sun obviously) - 4
- Arsenic
- 3rd degree burns
- Xeroderma pigmentosum
- Chronically draining ulcers
Precursor of melanoma
Dysplastic nevi
Does SCC occur on the upper or lower part of the lip?
Lower!!
*Upper is BCC
What is the difference between actinic keratosis versus cheilitis?
Cheilitis is a precursor lesion around the lip with “cutaneous horns”
Keratosis
What can the sudden appearance of multiple seborrheic keratoses be suggestive of?
Underlying GI malignancy
*Called Leser-Trélat sign!
**Always do biopsy of these seborrheic keratosis
Histologically, what condition has pseudo-horn cysts, and what are these?
Seborrheic keratoses
*Small cystic spaces in the epidermis filled with keratin
Histologically, what does dermatitis herpetiformis present as?
Dermal-epidermal separation with sub epidermal blisters & neutrophilic accumulation
*IgA staining in dermal papillae
Why does derma-epidermal separation occur in celiac disease?
IgA cross reacts with epidermal keratinocytes transglutaminase (eTG), disrupting cell anchoring & causing separation
Why is a blue nevus blue?
Tyndall effect
-Light wavelength scatters due to melanin within the dermis
What are blue nevus?
Deep, intradermal nevus in which clusters of nevus cells extend into the reticular dermis & subcutaneous tissue
Palisading nuclei are a common biopsy finding on what condition?
Basal cell carcinoma
*Palisade means fence like
