The document provides information on differentiating primary and secondary skin lesions and describes common dermatological terms and diagnostic techniques. It discusses the key steps in examining a dermatology patient, including assessing the distribution, type, shape and arrangement of lesions before taking a focused history. The history should explore the evolution, symptoms, medications, associated issues and risk factors. Diagnostic techniques mentioned include skin biopsy, KOH preparation, Tzanck smear, diascopy, Wood's light and patch testing.

1. Dr Subhasish Deb
Dept. General Medicine
Burdwan Medical College

2.  Skin is the largest organ in the body
 Advantage: no special instrumentation required
 Disadvantage: minor differences in shape and
colour
 Imp to differentiate PRIMARY from
SECONDARY lesions
 Ex: if an examiner focuses on a linear erosion
overlying an area of erythema and scaling, he may
incorrectly assume that the erosion is the primary
lesion while redness and the scales are secondary.
The correct interpretation would be that the pt has
a pruritic eczematous dermatitis with erosions
caused by scratching

3. Primary Skin Lesions
1. MACULE
 Flat – not raised above suface of
surrounding skin
 < 2 cm
 Coloured
 A Freckle or ephelid is a prototype
pigmented macule

5. 2. PATCH
 Flat lesion
 Large, > 2cm
 Colour different from surrounding skin
3. PAPULE
 Small solid lesion, < 0.5cm diameter
 Raised above surface (palpable)
4. NODULE
 Larger in size, 0.5-5cm
 raised

6. Paplue: acne

7. Nodule: Dermal melanocytic nevus

8. 5. TUMOUR
 > 5cm
 Solid, raised growth
6. PLAQUE
 Large, > 1cm
 Flat topped
 Raised lesion
 Edges may be distinct (psoriasis) or blend with
surrounding skin (eczematous dermatitis)

9. PLAQUE
Psoriasis
A
B
Exzematous dermatitis
1 2
3

10. 7. VESICLE
 Small, < 0.5cm diameter
 Fluid filled
 Raised above plane of skin
8. PUSTULE
 Vesicle filled with leukocytes
9. BULLA
 Fluid filled
 Raised
 Often translucent, > 0.5cm diam

11. Vesicle
Pustule
Bulla

12. 10. WHEAL
 Erythematous
 Raised
 Papule or plaque
 Usually representing short lived vasodilatation and
vasopermeability
11. TELANGIECTASIA
 Dilated, superficial blood vessel

13. Wheal
Telangiectasia

15. Secondary skin lesions
1. Lichenification : thickening of skin
characterized by accentuated skin fold
markings
2. Scale : Excessive accumulation of stratum
corneum
3. Crust : Dried exudate of body fluids that
may be yellow (serous crust) or red
(hemorrhagic crust)

16. Lichenification

17. Scales, ex: icthyosis Crust

18. 4. Erosions : loss of epidermis without loss of
dermis
5. Ulcer : loss of epidermis and at least a
portion of the underlying dermis
6. Excoriation : linear, angular erosions that
may be covered by crust and are caused by
scratching

19. Erosion
Excoriation
Ulcer

20. 7. Atrophy : An acquired loss of substance. In
the skin, this may appear as a depression
with intact epidermis (i.e loss of dermal or
subcut tissue) or as sites of shiny, delicate,
wrinkled lesion (i.e epidermal atrophy)
8. Scar : a change in skin secondary to trauma
or inflammation. May be hypo or
hyperpigmented

21. Atrophy Scar

23. Common Dermatological
Terms
1. Alopecia – Hair loss, may be partial or
complete
2. Annular – Ring shaped lesion
3. Cyst – soft, raised, encapsulated lesion filled
with semisolid or liquid contents
4. Herpetiform – Grouped lesions
5. Lechenoid – Violaceous to purpule, polygonal
lesions that resemble those seen in lichen
plannus

24. 6. Milia – Small, firm, white papules filled with
keratin
7. Morbiliform – Generalized, small
erythematous macules and/or papules
resemble those seen in measles
8. Nummular – coin shaped
9. Poikiloderma – skin that displays variegated
pigmentation, atrophy and telangiectases
10. Polycyclic – formed from coalescing rings or
incomplete rings
11. Pruritis – sensation that elicits desire to
scratch

25. Lichenoid
Milia

26. Poikiloderma
Polycyclic skin lesion:
Erythema multiforme

27. Approach to the pt
 Advisable to asses the pt before taking
extensive history
 This way objective finding can be integrated
with relevant history
 4 basic features must be noted:
1. Distribution of eruption
2. The types of primary & secondary lesions
3. Shape of individual lesions
4. Arrangement of lesions

28.  Examine skin, hair, nails, mucous
membranes of mouth, eyes, nose,
nasopharynx and anogenital region.
 1st view pt from 4-6 ft for general character of
skin and distribution of lesions.

29. Example
 When lesions are distributed on elbows,
knees & scalp, the most likely possibility
based solely on distribution is psoriasis or
dermatitis herpetiformis.
 The primary lesion in psoriasis is a scaly
papule that soon forms erythematous plaques
covered with white scale, whereas that of
dermatitis herpetiformis is an urticarial papule
that quickly becomes a small vesicle.

30. History taking
Emphasis on the following:
1. Evolution of lesions
a) Site of onset
b) Manner in which the eruption spread
c) Duration
d) Periods of resolution or improvement in
chronic eruptions

31. 2. Symptoms associated with the eruption
a) Itching, burning, pain, numbness
b) Anything relieved the symptoms
c) Time of day when symptoms most severe
3. Recent medications (prescribed + over the
counter)
4. Associated systemic symptoms (malaise,
fever, arthlagia)
5. Ongoing or previous illness
6. h/o allergies
7. Presence of photosensitivity
8. Review of systems

32. 9. Family history (melanoma, atopy, psoriasis,
acne)
10. Social, sexual and travel history

33. Diagnostic techniques
1. Skin Biopsy
2. KOH preparation
 KOH dissolves keratin
 Easy visualization of fungal elements
 Hyphae in dermatophye infection, pseudohyphae
and budding yeast in Candida
3. Tzanck smear
 For herpes virus infection (HSV or VZV)
 An early vesicle unroofed & the base scraped –
stain with Giemsa – mutinucleated epithelial cells
seen

34. 4. Diascopy
 Designed to asses whether skin lesion will blanch
on pressure
 To differentiate if a red lesion is hemorrhagic or
simply blood filled
 Urticaria will blanch on pressure while necrotising
vasculitis will not
 Performed by pressing a slide or a magnifying
lens against lesion
5. Wood’s light
 360 nm UV light by wood lamp
1. Erythrasma (by Corynebacterium minutissimum)
looks coral pink
2. Psudomonas colonisation apperas pale blue

35. 3. Tinea capitis (by Microsporum cnis or M. audouni)
exhibits yellow fluorescence
4. Freckles are accentuated bur postinflammatory
hyperpigmentation fades
5. Vitiligo appears totally white
6. Aslo aids in recognition of ash leaf spot in T.
sclerosis
6. Patch Test
 Testing sensitivity to specefic antigen
 Examined after a contact of 48hrs

36. Erythrasma
Tinea Capitis

37. Thank you