Musculoskeletal- Skin

Question 1

Scales found in eczema. psoriasis and SCC are characteristic of flaking off of which layer of epidermis?

Answer 1

Stratum corneum–> Stratum corneum has dead keratinocytes that slough off, so in scales stratum corneum is the one that flakes off.

Question 2

Which layer of epidermis is affected in Lichen Planus?

Answer 2

Stratum granulosum

(My granny likes me plainly, is about to die but not dead yet)–> Stratum granulosum has keratinocytes that are alive but thin.

Question 3

The difference between Stratum corneum and Stratum lucidum?

Answer 3

Both have dead keratinocytes, but stratum has dead keratinocytes that slough off.

Stratum lucidum is thickened in palms and soles.

Question 4

In a person, acanthosis nigricans which layer of epidermis is affected?

Answer 4

Stratum spinosum is increased in width/ also called acanthosis/ epidermal hyperplasia/increased in desmosomes because desmosomes are found in stratum spinosum.

(Acanthosis nigricans–> Negros have spiny hair/dreads)

Question 5

Acantholysis?

Answer 5

It is actually the seperation of epidermal cells from one another and that occurs in pemphigus vulgaris!!

(High yield because one can think that acantholysis is the seperation of epidermis from dermis)

Question 6

Desmosomes and hemidesmosomes are attacked in which conditions?

Answer 6

Desmosomes are found in Stratum Spinosum–> in fact, that is what makes the this layer spiny–> Autoantibodies to desmoglein 1
and/or 3 —> pemphigus vulgaris
Another name for desmosomes is macula adherens which they can definitely test you on.
(Desmosomes–> dicks–> spiny and dark and vulgar–> macula adherens, in stratum spinosum, cause pemphigus vulgaris)

Hemidesmosomes—-> keratin/keratinocytes to basement membranes( Hence, important to maintain the integrity of cell surface). Integrins are also a kind of hemidesmosomes!! (They can test you on this)
Autoantibodies—> bullous pemphigoid.

Question 7

What is the pathophysiology of the following states:

Dark Skin
Light Skin
Albinism
Vitiligo
Freckles
Mole

Answer 7

Dark Skin--> More melanin
Light Skin--> Less melanin
Albinism--> NO melanin
Vitiligo--> Melanocyte death
Freckles--> INCREASED MELANOSOMES
(Some freckles--> so increased melano-SOMES.)
Mole--> Melanocyte proliferation
(Mole on my chin is a pretty sight--> so increase in melano-CYTE)

Question 8

CD8+ cells are seen in which skin lesions?

Answer 8

1. Lichen Planus

Rete ridges have sharpened saw-tooth appearance/thickened stratum granulosum

2. Erythema multiforme–> associated with Mycoplasma pneumoniae, HSV, use of phenytoin, B-lactam drugs.

Question 9

Seborrheic dermatitis vs Seborrheic keratosis is seen in?

Answer 9

Seborrheic dermatitis–>associated with Parkinson disease.

Seborrheic keratosis–> proliferation of immature keratinocytes with keratinfilled cysts (horn cysts)–> seen in GI adenocarcinoma

Question 10

How are epidermal layers affected in psoriasis?

Answer 10

increased stratum spinosum (also called acanthosis)

decreased stratum granulosum

Question 11

2 high yield characteristics of urticaria/hives:

Answer 11

superficial dermal edema (Notice, it is dermal, not epidermal)
lymphatic channel dilation

Question 12

Benign capillary hemangioma of children vs adults?

Answer 12

Strawberry hemangioma in kids!–> size increase rapidly and then regresses at by 5-8 years of age.

Cherry hemangioma–> in middle-aged adults.

Question 13

Which 2 skin conditions are associated with pregnancy?

Answer 13

Melasma (mask like lesion)
Pyogenic granuloma (polypoid lobulated capillary hemangioma)

Question 14

Bacillary Angiomatosis vs Kaposi sarcoma.

Answer 14

Both found in AIDS. Look similar.
Bacillary Angiomatosis–> Caused by Bartonella infections, has neutrophilic infiltrate!

Kaposi sarcoma—-> caused by HHV-8–>has
lymphocytic infiltrate!
In uworld–> histo was written as spindle shaped cells and slit like vascular spaces.

Question 15

Glomus tumour orignates from?

Answer 15

modified smooth muscle cells of the thermoregulatory glomus body. (Asked in uworld)

Question 16

Liposarcoma (asked in NBME 20, and you did it wrong).

What is its characteristic cell?

Answer 16

Lipoblast is its characteristic cell.

In NBME 20–> It was written as adipocyte mass infilterating the muscle–> you did lipoma, but as it is infilterating the muscles it must be liposarcoma!

Question 17

Staphylococcal scalded

skin syndrome vs TEN

Answer 17

Exotoxin destroys keratinocyte attachments in stratum granulosum only (vs toxic epidermal
necrolysis, which destroys epidermal-dermal junction

(My granny is always angry/scalded–> Hence, scalded skin syndrome affect stratum granulosum)

Question 18

Nikolsky sign is positive in which 2 skin conditions?

Answer 18

>Staphylococcal scalded skin syndrome.
>SJS
>TEN (When SJS involves more than 30% of the total body surface)
>Pemphigus vulgaris
>Burns

Question 19

Which skin conditions occur on extensor surface elbows and knees?

Answer 19

Psoriasis and dermatitis herpetiformis.

Question 20

Dermatitis herpetiformis characteristic?

Answer 20

Remember, TIPS OF DERMAL PAPILLAE.

Deposits of IgA/fibrin and neutrophils present at tips of dermal papillae

Question 21

What will be seen in a patieint of dermititis herpetiformis?

Answer 21

Intestinal intra-epithelial lymphocytes will be seen–> because it is associated with CELIAC DISEASE.

(Very high yield)

Question 22

Which skin lesion is associated with Hep C?

Answer 22

Lichen Planus.

Question 23

UVA and UVB

Answer 23

UVB is dominant in sunBurn
UVA in tAnning and
photoAging( UvB reduced dermal collagen 1, 3 deposition and causes wrinkling. Vitamin A can oppose this effect)–> Aging and UVA affects the dermis.

Question 24

BCC vs SCC.

Answer 24

BCC–> most common, caused by UV-B–> upper lip.

SCC–> caused after actinic keratosis-> lower lip!