Lecture 1: Diagnosis of Skin Disorder 🎯 5 Questions

  • Important Historical Clues: Occupational history (chronic hand eczema), Travel history (Baghdad boils), Drug history (topical/systemic before lesions).
  • Examination Rules: Must be under day light or bright light. Undress patient. Examine hidden areas: oral cavity, hair, nail, palm, soles, and genitalia.
  • Macule vs Patch: Flat, color alteration. Macule (e.g. vitiligo). Large macule = Patch.
  • Papule vs Nodule: Elevated. Papule < 1cm (e.g., viral wart, xanthoma). Nodule > 1cm and deeper (e.g., Baghdad boil).
  • Plaque: Flat, disc-shaped elevated lesion (coalescence of papules) e.g., Psoriasis.
  • Wheal: Transient edematous whitish/pinkish lesion due to dermal fluid. Deeper/painful = Angioedema.
  • Blister: Fluid collection. Vesicle < 1cm (e.g., Dermatitis herpetiformis). Bullae > 1cm (e.g., Pemphigus).
  • Pustule: Visible pus < 1cm. Sterile (Pustular psoriasis) or Non-sterile (Folliculitis).
  • Vascular Lesions: Telangiectasia (permanent vessel dilation, e.g., Rosacea). Petechia (pinpoint bleeding, Vit C deficiency). Purpura (< 1cm, Henoch-Schonlein). Ecchymosis (> 1cm, Hemophilia).
  • Pathognomonic signs: Burrow (curved linear zigzag papule) -> diagnostic for Scabies.
  • Comedon: Primary lesion of Acne (oxidation = black/open, closed = white).
  • Scar types: Atrophic (Acne vulgaris) vs Hypertrophic (Keloid after burns).
  • Lichenification: Increased thickening/skin markings due to frequent scratching (defense mechanism, e.g., Neurodermatitis).
  • Ulcer vs Erosion: Ulcer = total loss of skin, heals with scar (Baghdad boil). Erosion = superficial loss, heals WITHOUT scar (Behcet disease).
  • Wood's Light (365 nm UV) MCQs:
    - Vitiligo = Ivory color (porcelain).
    - Tinea capitis = Greenish blue.
    - Pityriasis versicolor = Golden yellow.
    - Erythrasma = Coral red.
    - Pseudomonas = Green.
  • Diascopy (glass slide press): Urticaria wheal fades, but vasculitic purpura DOES NOT fade. Lupus vulgaris reveals Apple Jelly sign.
  • KOH 10%: Used to microscopically visualize Fungus.
  • Tzank Smear (blister base scraping): Acantholytic cells = Pemphigus. Multinucleated giant cells = Herpes simplex/zoster.
  • Immunofluorescence: Direct Immunofluorescence (DIF) applies dye directly to skin biopsy. Indirect Immunofluorescence (IDIF) applies dye to patient's serum first.

💡 Hints & High-Yield Points (Lecture 1)

  • The first step in skin examination is adequate lighting and undressing the patient.
  • Always differentiate Erosion (No scar) from Ulcer (Leaves a scar).
  • Wood's Light colors are guaranteed MCQs (Vitiligo=Ivory, Erythrasma=Coral Red, Tinea Capitis=Greenish Blue).
  • Diascopy perfectly differentiates Urticaria (Fades) from Purpura/Vasculitis (Does NOT fade).
  • Tzank Smear findings: Acantholytic cells = Pemphigus / Multinucleated giant cells = Herpes.

Lecture 2: Disorders of Sebaceous and Apocrine Glands 🎯 5 Questions

  • Sebum: Under androgenic control (NOT neural). Functions: lubricate, weak bactericidal, fungistatic, sunscreen.
  • Seborrhea Causes: Parkinsonism, Epilepsy, Polycystic Ovarian Syndrome (PCOS), Cushing syndrome.
  • Etiology: Increased androgen sensitivity (5-alpha reductase makes 5-dihydrotestosterone, or decreased Sex Hormone Binding Globulin SHBG). Pathogen: Propionibacterium acnes (uses lipase).
  • Clinical: Polymorphic (comedones, papules, pustules, cysts, scars). Primary lesion = Comedone. Usually asymptomatic.
  • Severe Variants:
    - Acne Conglobata: Nodulocystic, upper trunk/face, ugly scars.
    - Acne Fulminans: Conglobata + systemic signs (Fever, arthritis, high Erythrocyte Sedimentation Rate / ESR).
    - Pyoderma Faciale: Large bag of pus on cheeks.
  • Other Variants:
    - Infantile Acne: 1st 3 months due to transplacental maternal androgens. Tx: Systemic Erythromycin.
    - Drug-Induced: Monomorphic red papules. Causes: Corticosteroids, Oral Contraceptive Pills (OCPs), Halogens (iodide/bromide), Isoniazid (INH), Rifampicin, Lithium.
  • Note on Sulphur: Indicated for Acne vulgaris, Rosacea, Scabies, and Seborrheic eczema.
  • Systemic Antibiotics:
    - Tetracycline: 250mg-1.5g/day. Take on empty stomach. SE: gastric upset, photosensitivity, yellow pigmentation of child teeth. Contraindicated in pregnancy & children < 12y.
    - Minocycline: Absorption NOT affected by food.
    - Erythromycin: Safe for pregnant ladies & infants.
  • Hormonal: Cyproterone acetate + ethinyl estradiol (Diane). Only for females (PCOS/hirsutism). NOT for males.
  • Isotretinoin (13-Cis-retinoic acid): Dose 1mg/kg/day for 4 months. SE: Extreme dryness (lips, eyes), Hepatitis, highly Teratogenic (absolute avoidance of pregnancy).
  • Features: Middle 3rd of face (30-50y, usually women). Erythema, telangiectasia, papules, pustules. Exacerbated by sun, hot drinks, spicy food.
  • Parasitic link: Infestation by mite Demodex folliculorum.
  • Complications:
    - Eye: Blepharitis, keratitis.
    - Rhinophyma: Hypertrophy of sebaceous glands of nose (Whisky nose), more common in males.
    - Lymphoedema (lower eyelids).
  • DDx vs Acne: Rosacea lacks comedones.
  • Treatment: Tetracycline (Drug of choice). Topical Metronidazole (Flagyl). Rhinophyma needs cryotherapy.
  • Miliaria (Sweat duct obstruction in hot/humid climate):
    - Miliaria crystallina: Subcorneal block, infants, tiny vesicles.
    - Miliaria rubra: Intraepidermal block, Prickly heat, highly itchy.
    - Miliaria profunda: Dermoepidermal block, non-itchy papules.
    Tx: Vitamin C 500-1000mg, calamine, cooler climate.
  • Suppurative Hidradenitis: Apocrine acne (axillae, groin, perianal). High androgens + Strep/Staph. Associated with acne conglobata. Tx: like acne, incise/drain, Isotretinoin, excision.

💡 Hints & High-Yield Points (Lecture 2)

  • Sebum secretion is controlled by Androgens, not neural mechanisms.
  • The absolute absence of Comedones points towards Rosacea instead of Acne.
  • Tetracycline Rules: Empty stomach, contraindicated in pregnancy & kids < 12y (yellow teeth).
  • Isotretinoin is highly teratogenic; absolute avoidance of pregnancy is required.
  • Rosacea exacerbators: Sun, spicy food, hot drinks, alcohol, Demodex mite. Leads to Rhinophyma.

Lecture 3: Parasitic Skin Infections 🎯 4 Questions

  • Life Cycle (Rule of 8.8.8): 8 eggs/day, hatch after 8 days, mature after 8 days.
  • Nit vs Scale (Important MCQ!):
    Nit = Firmly attached, regular shape, Click sign POSITIVE, Wood's light white shiny, contains embryo.
    Scale = Easily slipped off, irregular, negative click, not shiny.
  • Pediculosis Capitis: Occipital/postauricular area. Secondary bacterial infection causes foul smell. Rule: Any pyoderma of the scalp is pediculosis until proven otherwise.
  • Pediculosis Corporis: Body louse lays eggs in seams of clothing. Causes Vagabond's disease (excoriation + hyper/hypo pigmentation in chronic bad hygiene).
  • Pediculosis Pubis: Crab louse. Sexually Transmitted Disease (STD). Look for Maculae caeruleae (bluish macules on skin).
  • Pediculosis of Eyelashes: Non-sexual transmission (infants). Misdiagnosed as seborrheic dermatitis. Tx: Vaseline or chloramphenicol to cause death by suffocation.
  • General Tx: Permethrin, Lindane. Repeat after 8 days to kill hatching nymphs.
  • Pathogen: Sarcoptes scabiei var. hominis.
  • Life Cycle (Rule of 3.3.3.3): Penetrate 3mm/day, 3 ova/day, hatch in 3 days, mature in 3 weeks.
  • Clinical Features: Intense generalized nocturnal itching. Primary lesion = Burrow (pathognomonic, grayish curved line).
  • Sites: Finger-webs, axillae, umbilicus, genitalia. Pathognomonic sign: rubbery papules in genitalia.
    *In infants*: affects palms, soles, scalp.
    *Sparing*: The back is NOT affected.
  • Treatment: Permethrin 5% (3 days). Treat all family members. Disinfect clothes.
    *Toxicity*: Lindane and Benzyl Benzoate are neurotoxic (AVOID in pregnancy, infants, epileptics). Use Sulphur 3-10% instead for them.
  • Types:
    - Leishmania tropica minor: Dry ulcer, urban, man-to-man, small scar, slow heal (1 year).
    - Leishmania major: Wet ulcer, rural, animal reservoir (rats, dogs) to man, fast heal (2-6m) but large ugly scar.
  • Vector: Sandfly (Phlebotomus papatasi).
  • Life Cycle: Amastigote (no flagellum, found in human macrophages/histiocytes). Promastigote (flagellated, found in Sandfly gut and culture).
  • Diagnosis: Giemsa stain of biopsy edges (sees Amastigotes). N-N-N (Nicolle-Navy-MacNeal) Media culture (sees Promastigotes). Leishmanin test (positive in 98%, valueless in endemic areas).
  • Treatment: Pentostam (Sodium Stibogluconate) intralesional or systemic (10mg/kg/d). Zinc sulfate. Systemic indicated for multiple, diffuse, or sensitive areas (eyelids).
  • Presentation: Wingless insect hiding in wall crevices. Night biter. Causes grouped wheals with central punctum in each lesion on exposed areas.

💡 Hints & High-Yield Points (Lecture 3)

  • Rule of 8.8.8 (Pediculosis): 8 eggs/day, hatch in 8 days, mature in 8 days.
  • Rule of 3.3.3.3 (Scabies): 3mm/day penetration, 3 ova/day, hatch in 3 days, mature in 3 weeks.
  • Scabies intensely spares the back but targets finger-webs and genitalia (rubbery papules).
  • Leishmania minor = Dry / Urban / Slow healing / Small scar.
    Leishmania major = Wet / Rural / Fast healing / Large ugly scar.
  • Amastigote = Human Macrophages, No flagellum. Promastigote = Sandfly gut / N-N-N Media, Flagellated.

Lecture 4: Papulosquamous Diseases 🎯 11 Questions

  • Definition: Non-pruritic well-defined pink plaques with silvery scales on extensor surfaces (elbows, knees, scalp, sacrum).
  • Genetics/Pathogenesis: HLA-Cw6. HLA-B27 associated with arthropathic, generalized pustular, Reiter's disease. Epidermal turnover drastically reduced to 10 days (normally 60). Decrease in cAMP, increase in polyamines.
  • Provocating Factors:
    - Trauma: Koebner's phenomenon (new lesion at scratch site).
    - Infection: Streptococcal tonsillitis triggers Guttate psoriasis.
    - Drugs: Beta-blockers, Lithium, Antimalarials, Steroid withdrawal.
    - Sunlight: 90% improve, 10% worsen. (Improves in pregnancy).
  • Clinical Signs: Auspitz's sign is positive (pinpoint bleeding when scratched).
  • Variants:
    - Guttate: best prognosis, post-tonsillitis in kids.
    - Nail: Pitting, onycholysis, subungual hyperkeratosis (70% cases).
    - Generalized Pustular (Zumbusch): Emergency! High fever, hypovolemia, high output heart failure.
    - Arthropathic: Negative Rheumatoid Factor. Affects Distal Interphalangeal (DIP) joints.
  • Histopathology: Parakeratosis (retention of nuclei in stratum corneum). Test tube elongation of dermal papillae. Munro microabscesses (Polymorphonuclear leukocytes in epidermis).
  • Treatment:
    - Topical: Coal tar, Dithranol (highly irritant, avoid face/flexures), Calcipotriol (Vitamin D3 analog - immunomodulator, odorless/colorless).
    - Systemic: Psoralen + Ultraviolet A (PUVA) (320-400 nm). SE: aging, cataract, malignancy. Contraindicated in pregnancy, kids <12, Systemic Lupus Erythematosus (SLE).
    - Methotrexate (Folic acid antagonist). SE: liver tox, bone marrow suppression. Wait till family complete.
  • Etiology: Viral? Suspected Herpes simplex type 7 (HHV-7). Give life-long immunity.
  • Clinical Features: Starts with Herald patch (large 2-5cm, solitary). 5-10 days later, secondary lesions in Christmas tree distribution on trunk lines. Lesions have collarette scales. Self-limiting (6-8 weeks).
  • Definition (The 5 Ps): Pruritic, Purple (violaceous), Polygonal, Plane (flat-topped), Papules/Plaques.
  • Signs: Wickham's striae (white reticular lines on surface). Koebner's positive. Oral mucosa involved in 30-70%. Nail changes include pterygium.
  • Clinical Variants:
    - Actinic LP: Common in Iraq/Egypt on sun-exposed areas. Asymptomatic dark purple patch surrounded by hypopigmented halo.
    - Graham Little syndrome: Scalp LP (scarring alopecia) + follicular keratosis on extremities + loss of axillary/pubic hair.
  • Histopathology: Degeneration of basal cells, Saw teeth appearance of dermoepidermal junction, Colloid bodies in dermal papillae, band-like lymphocyte infiltrate.
  • Treatment: Systemic Antihistamines, Topical/Intralesional/Systemic Steroids (used for extensive, oral ulcerative, scalp to prevent hair loss, nail to prevent destruction).

💡 Hints & High-Yield Points (Lecture 4)

  • Psoriasis triggers: Trauma (Koebner's), Beta-blockers, Lithium, Antimalarials, Steroid withdrawal, Strep tonsillitis (Guttate).
  • Psoriasis Histology buzzwords: Parakeratosis, Test-tube elongation, Munro microabscesses. Epidermal turnover = 10 days.
  • Pityriasis Rosea: Herald patch initially, then Christmas tree distribution with "Collarette scales". HHV-7 suspected.
  • Lichen Planus 5 Ps: Pruritic, Purple, Polygonal, Plane, Papules. Look for Wickham's striae.
  • Lichen Planus Histology buzzwords: Saw teeth DE junction, Colloid bodies, Basal cell degeneration.

Lecture 5: Pigmentary Disorders 🎯 4 Questions

  • Aetiology: Autoimmune disease (loss of melanocytes, assoc. with Addison's, Hashimoto's, Diabetes Mellitus (DM)). Neurogenic theory (toxic thiols/catechols destroy melanocytes).
  • Clinical: Depigmented macules/patches, heals via hair follicles forming brown macules. Koebner's phenomenon (KP) is POSITIVE.
  • Special Types:
    - Halo naevus: White area around melanocytic naevus.
    - Chemical: Due to phenol/thiol in rubber industry.
    - Vogt's Koyanagi syndrome: Vitiligo + deafness + uveitis + blindness (middle age viral infection).
  • Bad Prognostic Signs: KP positive, involvement of hands/feet, segmental type, childhood onset, white hair, associated autoimmune disease.
  • Treatment: Potent topical steroids, Psoralen + UVA (PUVA). If extensive/universal, use MonoBenzyl Ether of Hydroquinone (MBEH / Benoquin) to destroy remaining normal melanocytes permanently.
  • Albinism: Autosomal Recessive (AR). Deficiency of tyrosinase enzyme. Melanocyte *number* is normal but non-functioning. Hair bulb test separates Tyrosinase Positive (partial) from Negative (total, severe, blindness/photophobia).
  • Pityriasis Alba: Minor endogenous eczema. White scaly patches on faces of children (3-16y). Tx: Emollient (Vaseline), mild steroid.
  • Piebaldism: Autosomal Dominant (AD). White patch + white forelock present at birth (failure of neural crest melanocyte migration).
  • Tuberous Sclerosis: Ash leaf macule seen easily by Wood's light in infants with epilepsy.
  • Steroid Leukoderma: Linear hypopigmentation spreading along lymphatics post-intralesional injection.
  • Melasma: Face hyperpigmentation in young females. Precipitated by Oral Contraceptive Pills (OCPs), pregnancy, sun light.
    - Wood's light classification: Epidermal (shows contrast, easily treated), Dermal (no contrast), Mixed.
    - Tx: Bleaching (Hydroquinone 1-4%), sunscreens. Persistent after pregnancy (30% don't change).
  • Freckles vs Lentigo (MCQ focus!):
    - Freckles: Due to increased melanin production. Fade in winter.
    - Lentigo (Lentigines): Due to increased NUMBER of melanocytes. Do NOT fade in winter, not affected by sunlight.
  • Café au lait patch: >1.5cm brown patch. Seen in Neurofibromatosis and Albright's syndrome.
  • Becker Naevus: Upper trunk brown patch with coarse hair, onset 15-20 years old.
  • Berloque Dermatitis: Due to Psoralen in perfume + sun exposure.
  • Xeroderma Pigmentosa: Autosomal Recessive. Sun exposure causes extreme freckles and malignant tumors on face.
  • Endocrine: Addison's disease characteristically involves oral cavity pigmentation.
  • UVA (320-400 nm): Long wave. Causes tan and aging. Penetrates window glass. Causes immediate tanning.
  • UVB (290-320 nm): Middle wave. Main cause of Sun Burn. Absorbed by window glass. Causes delayed tanning.
  • UVC (200-290 nm): Short wave. Causes cell damage/malignancy. Prevented by ozone layer.
  • Skin Types:
    - Type I: Always burn, never tan (Blond/albino).
    - Type II: Always burn, sometimes tan.
    - Type III: Sometimes burn, always tan (Most Iraqis).
    - Type IV: Never burn, always tan (Most Iraqis).
    - Type V: Negro people.

💡 Hints & High-Yield Points (Lecture 5)

  • MonoBenzyl Ether of Hydroquinone (MBEH) is used strictly for universal Vitiligo to permanently destroy normal melanocytes.
  • Albinism vs Vitiligo: Albinism = normal number of melanocytes but absent Tyrosinase. Vitiligo = Autoimmune destruction of melanocytes.
  • Freckles fade in winter. Lentigo does NOT fade.
  • UVA Penetrates glass -> Causes Aging and immediate Tanning.
  • UVB is Blocked by glass -> Causes Sunburn and delayed tanning.
  • Xeroderma Pigmentosa causes deadly malignant skin tumors upon sun exposure.

📋 Comprehensive Comparisons (High-Yield)

Lesion Category Lesion Name Description & Key Features Clinical Example
Flat (Color Change) Macule Circumscribed alteration in skin color, NOT elevated, few mm. Vitiligo (small)
Patch Large macule, flat color alteration. Vitiligo (large)
Elevated (Solid) Papule Elevated solid lesion < 1cm (hyperplasia, edema, infiltrate). Viral wart, Lichen Planus
Nodule Elevated solid lesion > 1cm, deeper in the dermis. Baghdad boil
Plaque Flat, disc-shaped elevated lesion (coalescence of papules). Psoriasis
Fluid-Filled Blister (Vesicle) Well-circumscribed fluid collection < 1cm. Dermatitis herpetiformis
Blister (Bullae) Well-circumscribed fluid collection > 1cm. Pemphigus
Pus-Filled Pustule Visible free pus < 1cm (sterile or non-sterile). Folliculitis, Pustular psoriasis
Abscess Visible collection of pus > 1cm. Bacterial infection
Vascular / Blood Telangiectasia Permanent visible dilation of blood vessels. Rosacea
Petechia Pinpoint bleeding (extravasation). Vitamin C deficiency
Purpura Blood extravasation < 1cm (Does NOT fade on diascopy). Henoch-Schonlein purpura
Ecchymosis Blood extravasation > 1cm, no texture change. Hemophilia
Hematoma Hemorrhage under skin with elevation. Post-traumatic
Special Lesions Wheal Transient edematous whitish/pinkish lesion, itchy (dermal fluid). Urticaria
Comedon Keratin accumulation in hair follicle (open=black, closed=white). Acne Vulgaris
Poikiloderma Combination of atrophy, pigmentation, and telangiectasia. Sezary syndrome
Burrow Curved linear zigzag papule. Pathognomonic! Scabies
Lesion Name Description & Key Features Clinical Example
Scale Shedding of squamous cells (dry or greasy). Psoriasis, Pityriasis rosea
Crust Masses of dry exudates from fluid, pus, or blood. Inflammatory reactions
Scar (Atrophic/Hypertrophic) Replacement of normal tissue by fibrous tissue after healing. Acne vulgaris (Atrophic), Keloid (Hypertrophic)
Keratosis Thickened area of skin. Eczema
Lichenification Increased thickening and skin markings + hyperpigmentation due to rubbing. Neurodermatitis
Excoriation Removal of epidermis caused by severe scratching. Dermatitis herpetiformis
Erosion Superficial loss of skin, heals WITHOUT scarring. Behcet disease
Ulcer Total loss of skin, heals WITH scarring. Baghdad boils
Fissure Longitudinal cutting/slit in the skin. House wife dermatitis
Atrophy Thinning of the skin. Steroid misuse
Striae Trophic linear pink streak caused by teared collagen. Stria distencia
Pigmentation Area of altered skin color (hypo or hyper). Post-inflammatory
Feature Nit (Louse Egg) Scale (Dandruff/Flake)
Attachment Firmly cemented to hair shaft Easily slipped off
Shape Regular (oval capsule) Irregular
Click Sign Positive Negative
Wood's Light Test White shiny color Not shiny
Microscopy Contains light embryo No embryo
Feature Leishmania Tropica (Minor) Leishmania Major
Ulcer Type Dry ulcer Wet ulcer
Location/Setting Urban area Rural area
Transmission Cycle Man-to-Man (via Sandfly) Animal reservoir (Rats, Gerbils, Dogs) to Man
Healing Time Slow (takes 1 year) Fast (2 to 6 months)
Scar Appearance Minimal / Small scar Large ugly scar
Feature UVA (Long Wave) UVB (Middle Wave) UVC (Short Wave)
Wavelength 320 - 400 nm 290 - 320 nm 200 - 290 nm
Glass Penetration Penetrates window glass Absorbed by window glass Prevented by Ozone layer
Primary Clinical Effect Skin aging and immediate tanning Sun Burn and delayed tanning Cell damage, Malignancy
Tanning Mechanism Oxidation of already existing melanin (appears in hours) Production of NEW melanin (takes 2-3 days, lasts weeks) None (lethal to cells)
Abundance in Sunlight 100 100 0 (Blocked)
Feature Freckles Lentigo (Lentigines)
Pathogenesis Increase in Melanin production (Normal melanocyte number) Increase in NUMBER of Melanocytes
Winter Behavior Fades in winter Persistent (Does NOT fade in winter)
Relation to Sunlight Strongly affected (Appears on sun-exposed nose/cheeks) Not affected by sunlight (Appears on hidden areas too)
Appearance Multiple small oval brown macules < 5mm Irregular large brown macules and patches
Demographics Blond and red-haired people Simplex (Children) / Senile (Elderly on back of hands/face)