Urticaria and Drug Reactions Quiz

Urticaria

• Types include spontaneous, cold, solar, delayed pressure, and dermographism
• Acute urticaria lasts less than six weeks
• Chronic urticaria lasts more than six weeks
• 50% of cases are idiopathic (no known cause) and do not need further investigation
• 40-50% of cases are autoimmune, potentially associated with thyroid issues or H. Pylori infection
• Treatment options include antihistamines (first-line, daily; second-line, four times daily), Dupixent, doxycycline, or cyclosporine
• If a trigger is known, removing it is important
• If only angioedema is present, a work-up is necessary
• Generally, no constitutional symptoms, but if present, a work-up is recommended

Common Drug Reactions

• Penicillin is a common culprit
• Bactrim is a severe reaction

Morbilliform Rashes/Exanthematous

• Typically appear 7-14 days after drug exposure
• Often associated with penicillin and Bactrim use
• Red man syndrome is a particular reaction to vancomycin
• Symptoms include macular erythema that spreads from the back of the neck to the trunk, face, and arms
• Pruritus (itching) and sometimes hypotension may occur
• Treatment options include antihistamines, topical steroids, slow-infusion

Fixed Drug Eruption

• Characterized by round or oval patches that remain fixed to one spot
• Usually appears 1-2 weeks after the first exposure to the trigger drug
• NSAIDs, particularly naproxen, are a common cause
• More lesions might appear with continued exposure

Photosensitivity

• Phototoxic reactions appear as a severe sunburn-like rash
• This is not related to prior sensitization and is often caused by NSAIDs, doxycycline/tetracycline, hydrocortisone
• Photoallergic reactions require prior sensitization and can resemble lichen planus and are often caused by topical sulfa medications

Erythema Multiforme

• Minor cases are associated with HSV (Herpes Simplex Virus) but may not have systemic symptoms or mucosal involvement
• Major cases associated with Mycoplasma but can also be HSV
• Associated with systemic symptoms and significant mucosal involvement
• Treatment includes valacyclovir (antiviral), topical steroids, and oral steroids (if severe)

Stevens-Johnson Syndrome & Toxic Epidermal Necrolysis (TEN)

• Drug-induced eruptions occurring 7-21 days after drug use
• Includes mucosal involvement, organ damage, and skin peeling
• Frequent culprits include allopurinol, sulfa medications, and anticonvulsants
• Body surface area involvement helps distinguish Stevens-Johnson Syndrome (less than 10% body surface area) from Toxic Epidermal Necrolysis (over 30% body surface area)
• Prognosis is significantly affected by how quickly the drug is discontinued
• SCORTEN (a scoring system) helps predict mortality risk on days 1 and 3

Pemphigus Vulgaris

• Autoimmune blistering disease affecting the spinosum layer of the epidermis

Bullous Pemphigoid

• Autoimmune subdermal blistering disease at the dermal-epidermal junction
• Blisters are tense and cannot tear
• Associated with neurological disorders like multiple sclerosis, stroke, bipolar disorder, dementia, and Parkinson's disease
• Treatment options vary from topical steroids and doxycycline in mild cases to topical steroids, oral steroids, and rituximab in moderate-severe cases

Actinic Keratosis

• Small, dry, rough, erythematous, flaky lesions that are often felt before seen
• Precancerous lesions caused by sun exposure
• Ten percent of these lesions progress to squamous cell carcinoma
• Treatments include cryotherapy (for smaller lesions) and 5-fluorouracil (5FU) for multiple lesions

Basal Cell Carcinoma

• Most common, rarely metastatic skin cancer
• Increased risk with sun exposure and genetic factors
• Superficial BCC affects the epidermis; treatment includes electrodessication and curettage, 5-fluorouracil (5-FU), or surgery.
• Nodular BCC is red, raised, scaly, exhibits telangiectasias, bleeds easily, and presents with a pearly shiny appearance; excision, Mohs micrographic surgery, or topical 5-FU are indicated for treatment.

Squamous Cell Carcinoma

• Second most common skin cancer
• Can be red, scaly, or plaque-like
• Most dangerous form with a high likelihood of metastasis
• Risk factors include sun exposure, HPV, smoking, immunocompromised status, lichen sclerosis/planus, and chemical exposure
• Treatment options include topical 5-fluorouracil (5-FU), surgical excision (in situ), and MOHS surgery (invasive)

Melanoma

• Most common type is superficial
• Follow-up with dermatologist for 2 years after diagnosis is critical
• Dysplastic nevi (atypical moles) can be associated with increased risk
• Mild/moderate risk, reassurance is recommended; severe cases may require intervention (MIS)

Merkel Cell Carcinoma

• Very aggressive and rare skin cancer
• Characterized by a large nodule arising unexpectedly
• Treatments include punch or shave biopsies and referral to oncology

Kaposi Sarcoma

• Rare cancer affecting blood vessels and lymph vessels of the skin
• Associated with HHV8
• More common in people with a history of immunocompromised or organ transplant

Melasma

• Symmetric hyperpigmented patches on sun-exposed areas of the body (e.g., face, cheeks, forehead, and neck)
• Often a light to dark brown color
• Risk factors include female gender, pregnancy, and oral contraceptives.
• Treatment options include hydroquinone, topical steroids, and long-term sun protection.

Post-Inflammatory Hyperpigmentation

• Hyperpigmented macules or patches following skin trauma or injury
• Typically resolves within 6-12 months
• Treatment includes sunscreen and topical treatments (hydroquinone, corticosteroids, azelaic acid)

Acanthosis Nigricans

• Hyperpigmented, velvety patches or plaques
• Frequently seen on the neck and folds
• Associated with insulin resistance, obesity, and metabolic disorders
• Treatment options include topical retinoids, keratolytics (e.g., lactic acid, salicylic acid), and microdermabrasion

Vitiligo

• Depigmented (loss of pigment) macules and patches
• Destruction of melanocytes
• Risk factors include thyroid disease and family history
• Treatment includes sunscreen, topical steroids, tacrolimus ointment, and biologics (like opzelura cream)

Lichen Sclerosus

• Ivory white, itchy atrophic papules with a pink rim
• Risk factors include autoimmune dysfunction, prior skin diseases, and family history of thyroid disease/anemia/areata.

Pressure Wounds (Decubitus Ulcers)

• Bed sores due to prolonged pressure on bony prominences
• Common in patients with limited mobility
• Risk factors include sensory deficits, age, poor nutrition, and immobility
• Stages range from intact skin to full-thickness tissue loss
• Treatment focuses on prevention and management of infection and pressure

Arterial and Venous Ulcers

• Arterial ulcers present as punched-out lesions with severe pain (especially with movement)
• Venous ulcers are associated with a history of venous insufficiency with symptoms like pain, heaviness, and/or discoloration
• Diagnosis can include evaluation of the ankle-brachial index, while venous ulcers are diagnosed with venous duplex ultrasonography
• Common risk factors include smoking, diabetes, prior DVT/VTE, obesity, immobility.

Stasis Dermatitis

• Dry, pruritic (itchy), scaly, hyperpigmented rash on the lower extremities caused by venous insufficiency