Table of Contents
Structure of the Skin
The skin is the body’s largest organ and consists of three big layers, which are close-knit to each other and have different functions: Epidermis, dermis and subcutis.
Epidermis (upper skin)
The epidermis consist of a keratinized squamous epithelium, which is mainly formed by keratinocytes. Alongside the basal membrane, the melanocytes can be found as well, which make the skin pigment as well as Langerhans-cells (immune cells) and Merkel cells. The basal layer holds the stem cells of the skin. The skin is renewed regularly, starting from the basal layer.
The dermis is a layer of the skin that consists of connective tissue and is located between the epidermis and the subcutaneous fatty tissue. Next to the line between the epidermis and dermis is the dermo-epidermal junction, in which the basal membrane of the epidermis connects with the dermis. Rete ridges and anchoring fibrils ensure that under the impact of the shear forces, the epidermis does not detach from the dermis. Disruptions in this area can lead to typical blistering illnesses.
The dermis contains blood and lymphatic vessels, nerve fibres and sensory receptors (e.g. Meissner-corpuscles), hair, sweat and sebaceous glands. Besides the fibroblasts, which produce the extracellular connective tissue, additional cells can be found in the dermis: tissue macrophages, lymphocytes, mast cells.
The connective and fatty tissue underneath the dermis serves the isolation and the mechanical protection of the skin.
Dermatology is primarily a visual field. The basis of dermatological diagnostics is the systematic and careful examination of the entire skin. This examination should take place in daylight.
In case of an initial consultation no part of the skin should be skipped. That means that also the hands and soles, inframammary and the interdigital, inguinal, genital, axillary and perianal region should be examined as well the ears, adjacent mucous membrane like the lips, oral cavity, anus, conjunctivas and the nose, the skin appendages (hairs and nails) as well as the scalp.
In addition the overall skin condition should be assessed and described, concerning: complexion, condition, drought, turgor and smell.
Description of skin findings
The description of the anomalies of the skin found during examination are made with the assistance of the efflorescence gauge. The description of the efflorescences (Latin: “ex” = out, “florescere” = flower), the so called “flowers of the skin”, serves the uniform morphological description of skin abnormalities and is the basis for communication between dermatologists. Therefore the efflorescence gauge is a kind of “code”, which helps to describe nearly all of the pathological skin changes with just a few terms and modifications.
The efflorescences are divided into primary efflorescences, which arise on healthy, unchanged skin and are a direct consequence of the illness as well as into secondary efflorescences, which are the secondary change of a primary efflorescences.
|Macula (spot)||Outlined colour change, without increase of the substance. Different colours are possible.||Red: increased circulation (erythema), bleeding in the skin (purpura)
white: lowered melanin, e.g. vitiligo
brown: increased melanin
|Urticate (wheal)||Volatile protrusion of the skin, through exit of the serum||Urticaria, mosquito bite|
|Papule (nodules)||Increase of the substance higher than the skin level, the diameter is smaller than 0,5 cm||Lichen ruber|
|Nodes (knot)||Increase of the substance higher than the skin level, the diameter is bigger than 0,5 cm||Skin tumor|
|Plaque||Flat sublimed increase of substance of the skin||Eczema, psoriasis|
|Bulla (blister) vesicle (bubbles)||Cavity filled with liquid (e.g. serum, blood), possible in every layer of the three layers of the skin||Pemphigus vulgaris, herpes simplex|
|Pustule (pustule)||Cavity filled with pus, possible in every layer of the skin||Folliculitis, acne, Psoriasis pustulosa|
While the primary efflorescences occur on healthy skin, secondary efflorescences follow already present primary efflorescences.
|Squama (scale)||Thickening of the horny layer (stratum corneum) of the epidermis, whitish sheds||Psoriasis, tinea|
|Erosio (erosion)||Superficial defect of the substance of the epidermis, healing without scars||Pemphigus vulgaris|
|Excoriation (artefact of scratching)||Defect of the substance, which goes right through to the upper dermis. Scars are possible in case of healing of the defect||Abrasions, itching illness of the skin|
|Crust (crust)||Bearing of dried up secrete||Serum, blood or pus out of smaller wound|
|Ulcer (ulceration)||Defect of the substance which at least goes to the lower dermis, bad healing, scarring obligatory||Ulcer cruris|
|Rhagade||Crack shaped tears of brittle skin, in natural skin folds like the corner of the mouth and hands||Hyperceratotic-rhagadiforme eczema of the hand, crack of the corner of the mouth|
|Cicatrix (scar)||Wound closure with collagenous connective tissue after a deep defect of the substance. Possibly hypo- or hyper pigmented, caved-in, sublimed or the level of the skin||Scar after ulcer or trauma|
|Atrophy (skin thinning)||Tissue loss in the area of multiple skin layers. Thinning of the epidermis and dermis||atrophy because of steroids or age|
|Lichenification||Thickening of the skin with oversimplifying lichenification||Atopic eczema|
Description of the findings
The preparation of the dermatological finding should also always assess the overall clinical picture. A step by step approach can be helpful.
First, start with the description of the localization (area of the body) as well as the number of efflorescences (solitary, several or numerous herds). Based on this description it can be judged, whether it is a localized or a generalized phenomenon.
These terms can be helpful for closer description:
- disseminated (sowed)
- diffuse (fuzzy limited, extended)
- generalized (disseminated over the whole body)
- grouped (identical skin changes, lying directly next to each other)
- confluent (passing into each other)
- solitary (individually standing)
Subsequently the separate herds need to be described morphologically. This includes the size and form, limitation, color, consistency and quality of the efflorescences. The expansion is measured if necessary and specified in length or by comparison.
In general, an efflorescence that is located more deeply has a sharper limitation. The color of inflammatory efflorescences can reveal its localization: In the upper dermis, the efflorescences are mostly sharply limited and bright red, in deeper layers the limitation is blurred and the color purple. With a spatula, made of glass, the reaction to pressure can be tested: Is the efflorescence movable? Does the color change under pressure?
The description of attendant symptoms like signs of inflammation (erythema, overheating), pain, pruritus (itching), exudation and burning completes the skin findings.
The anamnesis is used to clarify the development of the disease and is supposed to lead to a diagnosis, supported by previous findings and other data. The anamnesis is also the first important contact to the patients before they undress in order to be examined. It is important to proceed gently and to turn from open, general questions to more “intimate” topics. Ask in a specific, unaggressive way. When in doubt, the relationship of trust between doctor and patient should not be compromised for the sake of a single question.
Important questions for the anamnesis
- When exactly did the symptoms/skin changes start?
- Where exactly did the skin changes start to appear?
- Do the skin changes lead to subjective physical complaints? (pain, itching, hot/cold feeling)
- What did the skin changes look like at first, did they change? How did they spread?
- What did you do so far to treat your skin changes?
Questions towards the family’s anamnesis as well as journeys abroad can supply important insights. Las but not least the psychosocial situation of the patient as well as the personal impairments caused by the skin changes should be questioned.
Simple clinical tests can be conducted during the examination and can contribute important information for making a diagnosis. One of these simple tests, the aforementioned palpation provides information about consistency, mobility, painfulness, heat or cold of the skin, pulsation and other characteristics of the efflorescence.
Crusts can be removed to assess the wound and the expansion of the wound. In case secrete is abstracted, it can also be assessed.
Furthermore there are specific clinical signs, which can give hints for certain characteristics of the skin or other illnesses.
Here the skin is irritated with a blunt object (e.g. a spatula made of wood) and the reaction is evaluated. The resulting reddish weals normally disappear quite quickly. A red dermographism in contrast occurs after 15 seconds and is a sign of local vasodilatation, which leads to a significant redness. A reflective vasodilatation can produce a reflex erythema.
A dermographism with an urticarial origin can occur a few minutes after the red dermographism and possibly last for minutes. Because of a local release of histamine, it leads to swelling of the stretched patterns and itching.
The white dermographism (dermograhism albus), noticeable as a white stripe on the skin, is a sign of local vasoconstriction and is a hint for an atopic tendency, i.e. a tendency towards hypersensitive reactions like atopic dermatitis (neurodermatitis, atopic eczema).
Also known as the phenomenon of the bloody rope, serves the Auspitz-phenomenon, the diagnostic of a psoriasis. If you scratch the scales of a psoriasis plaque with a spatula made of wood, the inflammatory dermis will appear underneath. If you scratch the exact same spot again with a wooden spatula, the dermis will be opened and a punctual bleeding, coming from the blood vessels of the papillary top will occur.
To examine the skin various, sometimes simple tools are used in the field of dermatology. Besides the wooden spatula (which e.g. is used for triggering a dermographism), a spatula made of glass, magnifying glass and a dermatoscope are used. Additionally, the Wood-light (UVA-light), sonography, and histological procedures are used during the diagnostic.
Spatula made of glass (diascopy)
The glass spatula (or transparent plastic) can be used for measuring the efflorescences. Through pressure on the efflorescence, bleedings (erythema, which cannot be pushed away) can be distinguished from vascular dilations (which can be pushed away).
Incident light microscope (dermatoscope)
The dermatoscopy is a non-invasive procedure, which helps to assess the superficial skin layers by courtesy of a dermatoscope with a 10 – 100 times magnification. An important area where the dermatoscope is used is the classification of skin tumors (pigmented and non-pigmented).
The medium frequency sonography (7.5 – 10 MHz) can present deep skin layers, veins, and lymphatic nodes. It is important e.g. for a basic diagnostic of malignant tumours: The primary tumor and regional lymphatic nodes are examined. The search for suspicious lymphatic nodes is conducted in the phase of planning and diagnostics as well as during follow-ups and therapy monitoring.
Sonography with a high frequency (20 – 50 MHz) is used for the examination of the epidermis, dermis and subcutis, e.g. for preoperative measuring of the thickness of a malignant melanoma.
The UVA-radiation (365 nm) of the wood-light can produce a colored fluorescence of hair and skin in case of present specific skin changes. A green fluorescence in case of microspore, red fluorescence in case of erythrism, white in case of onychomycosis and vitiligo.
In case of an unclarified diagnosis or to confirm a diagnosis a biopsy of the skin can be performed. In this procedure, parts of the skin changes are excised as a punching cylinder or a small spindle of the skin. After the fixation of the tissue sample, it can be histological examined.
Besides the evaluation of the epidermis, dermis and subcutis, it is possible to evaluate tumorous processes or autoimmunological illnesses by courtesy of immune histochemical procedures (antigen-antibodies-reaction) as well as immunofluorescence.
Popular Exam Questions on Dermatological Diagnostics
The answers are below the references.
1. The phenomenon of lichenification is defined in the field of dermatology as…
- …intraepidermal blistering.
- …loss of tissue in the area of multiple skin layers.
- …crack formed tears of brittle skin.
- …defect of substance, which goes up to the upper dermis.
- …thickening of the skin with coarsened lichenification.
2. An erosion of the skin…
- …heals without scars.
- …is a defect of substance, which goes up to the upper dermis.
- …never reaches the epidermis.
- …is defined as a cavity, filled with pus.
- …heals always with scarring.
3. A white dermographism is a diagnostic hint for…
- …lichen ruber.
- …psoriasis pustulosa.
- …atopic diathesis.
- …atrophy of the skin, because of the age.
- …tinea corporis.