Dermatology Lecture 12 PDF

# Dermatology ## Lecture 12: Erythema Multiforme & nodosum & Drug reactions & Epidermal necrolysis & Pemphigus vulgaris ### Erythema Multiforme (E.M.) **Def:** - Acute self-limited skin disease characterized by target or iris lesion. **Etiology:** - Immune mediated common reaction pattern to...

# Dermatology ## Lecture 12: Erythema Multiforme & nodosum & Drug reactions & Epidermal necrolysis & Pemphigus vulgaris ### Erythema Multiforme (E.M.) **Def:** - Acute self-limited skin disease characterized by target or iris lesion. **Etiology:** - Immune mediated common reaction pattern to various antigenic stimuli such as: - **Infections:** - **Viral:** herpes simplex (The most common precipitating factor) - **Mycoplasma infection**. - **Drugs** - **Idiopathic** **E.M. has two subtypes: E.M. minor & E.M. major.** ### Erythema Multiforme (E.M.) **E.M. minor:** **Prodroma:** - Is absent or mild. **Skin lesions:** - **without** mucous membrane involvement. **Clinical Picture:** **Skin lesions:** - **Distribution:** - Bilateral & symmetrical distribution on the extensor surface of extremities (hands, feet, forearm). - Face, neck and trunk are less commonly affected. - **Shape:** - Polymorphic - The most characteristic is the target or iris lesion. **Target or Iris Lesion:** - Is circular with three zones (alternating dark and light): - **Central:** cyanotic or purpuric, Vesicle or bulla may occur in the centre - **Pale Ring** - **Periphery:** erythematous & Edematous area surrounding the pale ring - **Asymptomatic but** there may be itching or burning sensation. ### Erythema Multiforme (E.M.) **E.M. major:** - **Skin lesions** with involvement of mucous membrane - **Systemic symptoms** are always present - (Fever, occasionally arthralgia (constitutional +ve) or pneumonia) - **Skin lesions:** as E.M minor or severe wide-spread Vesiculo-bullous eruption - **Mucous membrane lesions:** - **Oral:** erosions, vesicles and bullae - **Lips:** haemorrhagic crusts - **Eyes:** conjunctivitis, corneal ulcer - **Nasal** - **uretheral and anal mucosa** may be inflammed and eroded ### Erythema Nodosum **Def:** - Inflammation of subcutaneous fat (panniculitis) presents as an acute self-limited painful nodular erythematous eruption. - It is an allergic reaction to: - **Infections:** - **Bacteria:** streptococci - **Viruses:** hepatitis, infectious mononucleosis, upper respiratory tract infection - **Mycobacteria:** leprosy - **Drugs:** sulfa, contraceptive pill.. - **Others:** Sarcoidosis, malignancy, (enteropathies) IBD. - **Idiopathic:** 30-50% **Prodroma:** URT infections **General:** - Fever, malaise, arthritis, or arthralgia **Skin lesion:** - Painful tender, bilateral, Shiny red nodules - Healing: Bruise colour changes. - **site:** Chin of tibia (commonest), occasionally forearm and thigh - Show bruise-like colour changes during regression. ### Course: - E.M. usually fades within 2-4 weeks - E.M. tends to recur (in 30 % of cases ) - Spontaneous resolution in about 2-6 weeks without residual scarring, - However, recurrence may occur ### Treatment:: - **Elimination of cause** - **Symptomatic and supportive** - **Prevention (Recurrent cases):** - Oral acyclovir (400 mg twice daily for 6 months) to prevent recurrence of herpes associated E.M - **Treatment of the cause.** - **Bed rest and supportive bandages.** - **Non-steroidal anti-inflammatory drugs (NSAIDs)** - **potassium iodide for 2 weeks in severe cases** # Drug Reactions **Definition:** Drug reaction is harmful, unintended, response to drug in therapeutic dose. **Mechanism:** allergic or non-allergic **Clinical picture:** - **Severe life –threatening drug reactions:** - **Anaphylactic shock:** pallor, hypotension, bronchospasm, angioedema - **Erythroderma** - **Epidermal necrolysis:** Stevens-Johnson Syndrome & Toxic epidermal necrolysis (TEN) *Page 7* - **Drug reaction with eosinophilia and systemic symptoms (DRESS):** skin rash, facial oedema, eosinophilia, lymphadenopathy and organ affection (liver, kidney,..) **Other forms of drug reaction:** 1. **Urticaria (Penicillin, aspirin)** 2. **Exanthematous rash:** - Red maculopapular rash (like measles) 3. **Photosensitivity (Psoralen, Tetracycline).** 4. **Vascular eruption or purpuric lesion** 5. **Lichenoid eruption** 6. **Bullous eruption** 7. **Acne-form eruption:** inflammatory papules or pustules that have a follicular pattern - (corticosteroids, ACTH, Bromide, lodide, Isoniazide) 8. **Pigmentation:** antimalarial, phenothiazine, gold 9. **Alopecia (following chemotherapy)** 10. **Fixed drug eruption:** - It characterisitically recurs in the same sites each time the drug is administered. - Common drugs causing fixed eruption are: Sulfonamides, NSAIDs - **Clinical picture:** - Well-defined round or oval plaque of erythema & oedema. Bulla may develop on the top - Healed lesion is hyperpigmented (dark brown to violet) - **Common sites involved are:** lips, anogenital area (glans penis), but can occur anywhere. ### Diagnosis of drug reactions: 1. **abrupt onset Symmetric cutaneous eruption** 2. **History of drug intake.** 3. **De-challenge test:** The eruption improves when the suspected drug is stopped. (clear in 2 weeks on withdrawal) 4. **Re-challenge (oral provocation test))** ### Treatment of drug reactions: - **Elimination of the offending drug** - **Symptomatic treatment:** - **Antihistamines.** - **Topical steroid.** - **Systemic steroids in severe cases.** # Epidermal Necrolysis ### (Stevens-Johnson Syndrome & Toxic epidermal necrolysis) **Definition:** - Acute, drug induced, life-threatening mucocutaneous reactions - Characterized by extensive necrosis and detachment of the epidermis. - The two conditions differ only in the percentage of body surface area affected: - **Stevens-Johnson Syndrome (SJS):** less than 10% - **SJS-TEN overlaps:** 10-30% - **Toxic epidermal necrolysis (TEN):** more than 30% **Prodroma:** - Of URT symptoms; High fever, painful skin and weakness. **Clinical features:** - **Skin:** - Erythematous and purpuric macules on trunk and proximal limbs → flaccid blisters → epidermal detachment and large confluent oozing erosions - Nikolsky sign is positive (firm sliding pressure on normal appearing skin → detachment of intact superficial epidermis) - **Sites:** mainly localized to face,upper trunk, and hands - **Mucous membrane:** - Involvement in 90% of cases ( always at least two sites) - Erythema and painful erosions of buccal, ocular, and genital mucosa - **Visceral involvement:** - Is possible (pulmonary, GIT, renal) **Prognosis:** - Mortality rate is up 25%. - Death may be due to sepsis, electrolyte imbalance or organ failure. **Ttt:** - Early (immediate) withdrawal of suspected drugs. - Rapid initiation of supportive care in intensive care burn unit. # Pemphigus vulgaris **Definition:** - Autoimmune disease in which autoantibodies are formed against intercellular bridges of the prickle cell layer. - This results in acantholysis and formation of intraepidermal bullae. - Incidence: Rare chronic disease, usually affects adults. (4-5th decades) **Clinical picture:** - **Lesion:** - Characterized by flaccid bullae arising upon normal skin and mucous membranes. - The bullae rupture easily leaving painful erosions & crusts. - Painful erosions on mucous membrane. - **Complication:** Infection, fluid & electrolyte imbalance may result in death. - **Nikolsky sign is positive** - **Sites:** commonly involved are scalp, intertriginous area and umbilicus, but in severe cases any site can be involved. **Treatment:** - Refer to dermatologist - Systemic steroids & immunosuppressive (cytotoxic) drugs. # Case Scenarios - **Case 1 scenario** - Mona is a 40-year-old lady with erythematous asymptomatic skin lesions on hands and feet of two weeks duration. - One week before the appearance of these lesions she had common cold and developed sores and crusts on lips. - **Skin exam:** - MONA was diagnosed to have erythema multiforme after herpes simplex infection - **Case 2 scenario** - Ola is a 29-year- old lady presented to emergency room with a painful,expanding and sloughing rash. - She was recently diagnosed to have a urinary tract infection, on treatment with Bactr. - **skin examination** - Erythematous erosions, mainly localized on the face, upper trunk and hands - Lesions began as flaccid blisters - **Answer:** - Ola was diagnosed to have severe drug reaction of Epidermal Necrolysis spectrum. - This spectrum includes Stevens Johnson Syndrome and toxic epidermal necrolysis. # Questions **Q: What is the characteristic lesion of erythema multiform?** - **A:** target lesion **Q:What is the characterestic lesion of erythema nodosum?** - **A:** nodules **Q:Mention two life threatening drug reactions.** - **A:** DRESS - **SIS and TEN Spectrum** **Q: What is the primary lesion of pemphigus vulgaris?** - **A:** flacid bullae **What is the difference between a vesicle and a bulla?** - **a)** Depth (distinguishes erosion and ulcer) - **b)** diameter - **c)** Etiology (morphologic terms, not etiologic) - **d)** Location (both can occur anywhere) - **e)** Presence of hemorrhage (either vesicles or bullae may be filled with blood) - **Answer:** B **1- bullae are expected finding in:** - **a)** psoriasis - **b)** pityriasis rosea. - **c)** pityriasis alba. - **d)** lupus vulgaris. - **e)** pemphigus. - **ANS: 1-e** **2- Target lesion occurs in:** - **a)** Pemphigus vulgaris. - **b)** Acne vulgaris. - **c)** Erythema a multiforme. - **d)** Lichen planus - **e)** Acne vulgaris - **A:** c **3- Erythema multiforme is characterized by:** - **a)** Shins of the tibiae are the most common sites - **b)** Could be precipitated by herpes simplex infection - **c)** Painful subcutaneous nodular erythematous eruption - **d)** Regress with bruise like colour changes. - **e)** Infectious disease - **ANS: 3-b**