Little Red Riding HoodA Dermatologic Journey

Children around the world know about Little Red Riding Hood’s famous journey to Grandma’s house, but few know the real reason behind it.

For you see, Little Red Riding Hood was a sickly child, afflicted in particular with skin problems. In fact, her parent’s can’t remember a single day in her life where there wasn’t some type of rash or lesion on their poor daughter.

But as luck would have it, one day she awoke with completely clear skin (‘cause that kind of thing happens in Fairy Tale Land). Her parents, normally afraid that their Little Red Riding Hood may transmit something to sickly Grandma laying in bed, immediately took this opportunity to send Little Red Riding Hood on a journey to Grandma’s House...

This is the story of that journey.

Hopefully by the end you will be more familiar with problems of the skin, and be able to:

• Identify the most common morphological presentations of skin lesion.• Be able to fully describe any skin lesions based on:

• Shape, • Arrangement, • Color, • Distribution and • Morphology.

1. ShapeBefore she could leave, Little Red Riding Hood had to put her toys away. Her favourite was a block matching game from which she learned the shapes and arrangements that her skin lesions could take:

Dome-Shaped Pedunculated Verrucous Umbilicated Flat-Topped

Discoid/Nummular Annular Targetoid

Linear Serpiginous

Grouped/Clustered

2. Arrangement

3. Distribution

After her toys were neatly away, Little Red Riding Hood’s parents inspected her one last time from head to toe for any signs of skin problems. They knew that certain skin conditions follow specific distributions on the body, for example:

Acne Vulgaris

Atopic Dermatitis

Photosensitive Eruptions

Psoriasis

With perfectly clear skin, Little Red Riding Hood was ready to leave and went to pick up her cloak. She wore cloaks because they covered most of her body, and hid her skin lesions from view.

4: Color

So little Riding Hood left her home, and the great expanse of varied land she had to cross on the way to Grandma’s house came into view. Undaunted, she set out on her way...

There were many different color options, because skin lesions can take on many different colors. Any given day Little Red Riding Hood would pick the one that would hide most of her lesions best.

First she came to a vast flat grassland, as flat and smooth as a clear path of skin. “What a beautiful field!” she exclaimed.

And it was, absolutely perfect save for a few discolored patches of grass here and there.

The big patchy ones she called patches

and the little ones she called macules

for this is what the doctors called discoloured areas that were flush with her own skin.

Patch: Large macule.Example: Cafe-au-Lait Spot

Macule: Flush, flat lesion that is implapable (can only see due to color change). Usually less than 1.5cm in diameter. Example: Ephelides (freckles)

Walking through the grasslands, she noticed that it was not all flat, as she saw two hills up ahead. She named them after different sizes of bumps on her skin.

The smaller, cuter one she called a:

Papule

The bigger one, she called a:

Nodule

Nodule: Large papule.Example: Basal Cell Carcinoma

Papule: Raised solid roundish lesion less than 1cm in diameter.Example: Blue Nevus

Making it past the hills, she came upon three different types of raised landscape.

The third was an area of dried mud stuck onto the top of the normally

flat grassland. This reminded her of what doctors call a crustcrust.

One was raised and flat on top just like the grasslands. A raised flat lesion on

the skin is what doctors called a plaque plaque she thought.

Another was just like the first, except there seemed to be a lot more grass growing over it, so much that some died and was flaking off. This looked to

her a lot like what doctors call a scalescale.

Plaque: Raised, flat palpable lesion greater than 0.5cm in diameterExample: Pityriasis Rosea

Crust: Serum, blood exudate firmly attached to the skin. Occurs when plasma exudes through an eroded epidermis. Not easily detached Example: Impetigo

Scale: Thickened flake of stratum corneum (top layer of the skin), easily detached. Example: Psoriasis

Following the raised landscapes she saw a rough jagged mountain arise from the surface of the land.

This reminded her of keratosis skin problems, chunks of rough keratinocytes breaking the smooth even surface of the skin.

Keratosis: Horn-like overgrowth of the skin with involvement of keratin. Example: Seborrheic Keratosis

Passing by the mountain, she saw a volcano, the crater filled with angry boiling lava and rock.

She noticed it was quite similar to her pores, when filled with dead skin and immune cells.

The docs called would call it an open comedone, the kids who sometimes poked fun at her called them blackheads.

If the volcano opening was closed off, covered with a thin layer of

earth she thought, it would be much like a closed comedone, or whitehead.

Example: Closed Comedones (whiteheads)

Comedo: Blocked pilosebaceous duct.

Example: Open Comedones (blackheads)

After carefully passing by the volcano Little Red Riding Hood was startled to see an earthquake shaking an area of grassland! This was the weirdest earthquake she’d even seen, for circles of land would randomly rise and fall with no particular pattern.

This, she thought, looks exactly like the hives, or wheals as the doctors called them, that present in this way on her skin when she has an allergy.

Wheal: Raised areas of dermal oedema. Example: Urticaria (hives)

After the earth stopped moving, Red Riding Hood walked on. She was happy to see smooth grasslands once again, but noticed that in some places the grass and soil was either thin, completely gone, and even as deep as the bedrock in one place.

With the earth completely gone:

The deeper areas of eroded earth:

The thinning areas were like:

Atrophied skin Erosions Ulcers

Atrophy: Thinning of the epidermis, dermis, or both.Example: Keloid

Erosion: Loss of the epidermis.Example: Tinea Pedis

Ulcer: Loss of the epidermis and dermis.Example: Leishmaniasis

Very close to Grandmother’s House, Red Riding Hood’s foot started to ache.

She took off her sock and shoe to reveal:

A small blister which doctors call a:

Vesicle

A big blister which doctors call a: Bull

And a callus which doctors call:

Lichenification

A blister filled with pus which doctors call a:

Pustule

Lichenification: Thickened skin with exaggerated epidermal markings caused by chronic scratching.Example: Eczema

Vesicle: Fluid filled lesion less than 0.5cm in diameter.Example: Varicella Zoster

Bull: Fluid filled lesion greater than 0.5cm in diameter. Example: Bullous Pemphigoid

Pustule: Pus filled vesicle.Example: Insect bite.

Little Red Riding Hood finally made it to Grandmother’s house. Grandmother welcomed her warmly, and Red Riding Hood told her about all the sights she saw on the way.

5. Morphology

Patch Macule

PapuleNodule

See if you can recall the names with Little Red Riding Hood:

Plaque Scale Crust

Keratosis Comedone Wheal

UlcerErosionAtrophy

LichenificationPustuleVescicleBull

Little Red Riding Hood and her Grandma finally got a chance to spend some quality time together (because Little Red Riding Hood took the long way to Grandma’s house, the hunter had taken care of the wolf long before she reached her destination). Especially important in Littler Red Riding Hood’s life, Grandma learned how to fully name skin lesions. As you may remember, it includes 5 elements:

1. Shape

2. Arrangement

3. Color

4. Distribution

5. Morphology

For example:

One day after playing in the woods by her house, Little Red Riding Hood came home with painful red circular vesicles in a linear arrangement on her distal left forearm.

What did she have? A reaction to poison ivy

Coming to the end of the journey with Little Red Riding Hood, let’s see if you can apply the knowledge learned while on this trip by answering a couple of practice questions:

Try to identify the following skin conditions. They’re tough, require a little prior knowledge and are meant more than anything to illustrate the central importance of accurate and detailed lesion description in diagnosis of dermatological problems:

D: erysipelas

On a family medicine rotation, you see a 9 year old boy with numerous small vesicular lesions on erythematous bases. The lesions are all in different stages of evolution and appear over the trunk and face. The most likely diagnosis is:

B: chickenpox

You are rounding in a nursing home and encounter this 71 year old gentleman. He suffered from malaise, headache and fever before the eruption. He also seems to remember a tingling sensation in the area. He is currently distressed and worries that it is "some sort of cancer". What is the likely pathogen?

Question 1:

C: Measles Virus

A: Varicella Zoster Virus (VZV)

Question 2:

B: Herpes Simplex Virus (HSV)

D: Human Papillomavirus (HPV)

A: molluscum contagiosum

C: impetigo

The End

Credits:

Author: Jakub Sawicki

Special thanks to Sheila Pinchin from the Office of Health Sciences Education and Amy Allcock from MEdTech for their invaluable help in putting this module together.

Practice Questions courtesy of Nicole Hawkins from Queen’s Meds 2009. Many more helpful resources and questions available at DermStudent.com