Dermatology - Systematic Breakdown To Master Dermatology

Psoriasis presents as silvery, scaly papules and plaques, sharply demarcated and salmon colored, commonly on the knees and elbows, driven by CD8 and CD4 T cells with dendritic cells.

Identify urticaria as an allergic skin condition with itchy hives and edema, and review acute versus chronic forms and triggers such as dermatographism, cold, cholinergic, delayed pressure, and solar urticaria.

Raynaud phenomenon causes distal finger color changes from vasoconstriction, ischemia (white) to hypoxia (blue) and reperfusion (red), triggered by cold or stress, treated with calcium channel blockers or prostacyclin analogs.

Understand autoimmune polio, myositis, and dermatomyositis, driven by antibodies such as tRNA synthetase, SRP, and anti-Mi-2, with CK monitoring, heliotrope rash, cancer links, and treatment with IV steroids and immunosuppressants.

Explore scleroderma as a systemic autoimmune disease causing skin fibrosis and visceral involvement. Recognize esophageal dysmotility, pulmonary hypertension, renal crisis, and diffuse versus limited forms, including crest syndrome.

Learn how dermatologists describe skin lesions by color and shape, using terms like macular, patches, papules, plaques, pustules, physical, Ebola, wheels, scales, and crusts.

Explore how tight junctions, adherens belts, desmosomes, and gap junctions connect epithelial cells to the basement membrane, enabling barrier function and intercellular communication, with Pemphigus vulgaris linked to desmosome autoantibodies.

Explore the skin’s three layers—the epidermis, dermis, and subcutaneous fat—with a focus on epidermal strata from basale to corneum, including keratin, melanin, and cell junctions.

Corticosteroids remain the first-line dermatology treatment, given topically, orally, or by injection, with step up/down dosing and occlusion to modulate b and t lymphocytes in acute inflammation and eczema.

Isotretinoin reduces sebum production to treat severe acne. It shrinks sebaceous glands, is highly teratogenic, and requires liver and lipid monitoring.

Minoxidil opens potassium channels to induce vasodilation, supporting its use for alopecia. Synchronizing hair follicle life cycles aligns growth and shedding.

Explore methotrexate's anti-inflammatory and immunomodulatory actions, including T-cell and cytokine effects and folate antagonism, benefiting atopic dermatitis and chronic spontaneous urticaria, with pregnancy and liver safety considerations.

Apply calcineurin inhibitors to suppress t-cell activation in severe psoriasis or atopic dermatitis. Cyclosporine binds cyclophilin, tacrolimus binds FKBP; both reduce t-cell proliferation but pose neurotoxicity and renal risks.

Penicillin inhibits peptidoglycan cross-linking by binding to penicillin binding proteins, serving as a beta-lactam antibiotic used in dermatology against gram-positive and some gram-negative infections. Counter beta-lactamase-mediated resistance with beta-lactamase inhibitors.

Tetracyclines including doxycycline, tetracycline, and minocycline are dermatology-useful bacteriostatic antibiotics; doxycycline treats MRSA and is renally safe. Avoid calcium, iron, and expired meds to prevent reduced absorption and resistance.

Trace acne pathophysiology from sebaceous unit plug to inflammation driven by Propionibacterium acnes and free fatty acids. Androgens increase sebum, with mild to severe forms, treated by isotretinoin or alternatives.

Stevens-Johnson syndrome, often triggered by anti-epileptic medications and other drugs, causes dermal-epidermal separation with mucosal involvement; stop the offending drug promptly.

Identify bullous pemphigoid as a type II hypersensitivity autoimmune disease with autoantibodies against the basement membrane, causing tense blisters that spare mucosa and show linear immunofluorescence with Nikolsky sign negative.

Pemphigus vulgaris results from type II hypersensitivity autoantibodies against desmoglein 1 and 3, causing intraepidermal bullae, mucosal involvement, and a positive Nikolsky sign, with reticular immunofluorescence and acantholysis.

Explore dermatitis herpetiformis, a skin manifestation linked to active celiac disease, with vesicular lesions on elbows, knees, and buttocks, IgA deposits, and treatment through a gluten-free diet.

Erythema multiforme forms blisters and red to purple lesions in various shapes, most commonly target lesions, and arises from infections or drugs; treatment removes the trigger and reassesses for resolution.

Sunburns arise from UV radiation from the sun, with two types: UVA and UVB. DNA breakage and mutations trigger apoptosis and inflammation, and excessive damage can lead to cancer.

Compare pemphigus vulgaris and bullous pemphigoid to show autoantibody targets: desmosomes versus basement membrane, type two hypersensitivity, mucosal involvement in pemphigus, and linear versus intercellular immunofluorescence patterns.

Explore albinism, where normal melanocyte numbers mask reduced melanin from impaired tyrosine activity, producing white skin and hair, with UV cancer risk, ocular effects, and autosomal recessive or X-linked inheritance.

Identify vitiligo as an autoimmune attack on melanocytes causing well-demarcated patches, with biopsies showing fewer melanocytes and screening for other autoimmune disorders; treat with camouflage, corticosteroids, tacrolimus, and light therapy.

Identify melanocytic nevi, common benign moles 6 mm or less, usually harmless but with malignant potential in congenital or atypical-shaped lesions, observed unless malignancy is suspected.

Acanthosis nigricans appears as symmetrical, thickened, hyperpigmented patches in skin folds like the axilla and neck. It signals insulin resistance and obesity, with links to type 2 diabetes and PCOS.

Basal cell carcinoma, the most common skin cancer in sun-exposed areas like the face, presents with a central ulcer and rolled borders and is treated mainly by surgical excision.

Squamous cell carcinoma, second most common skin cancer after basal cell carcinoma, links to sun exposure and immunosuppressive drugs, presenting as lesions with nodal involvement; actinic keratosis is a precursor.

Identify melanoma as a high-risk skin cancer linked to sun exposure, ultraviolet light, tanning beds, and fair skin. Apply ABCDE criteria and depth-driven prognosis, noting BRAF mutations treated by vemurafenib.

Identify actinic keratosis as small, rough, pre malignant lesions in sun-exposed areas; treat by avoiding the irritant, using skin creams and gels, moisturizing, cryotherapy, excision or scraping, and photodynamic therapy.

Understand keratoacanthoma as a rapid-growing, keratin-filled lesion that forms horn-like projections, may spontaneously regress, and carries cancer potential with possible transformation to squamous cell carcinoma.

Kaposi sarcoma is a malignant endothelial cell cancer caused by HIV or human herpesvirus, presenting reddish raised lesions anywhere, with lymphocyte infiltrates on biopsy and HIV treatment can resolve them.

Angiosarcoma is a malignant vascular cancer often presenting late, treated with surgery, radiation, and chemotherapy, and linked to prior radiation, mastectomy with lymphedema, sun-exposed skin, or liver metastasis.

Bacillary angiomatosis, caused by Bartonella after cat scratches, affects immunocompromised individuals, causing red pedunculated vascular lesions in skin and organs, treatable with antibiotics.

Identify cherry hemangiomas as common benign 2–4 mm reddish papules often on aging skin. Diagnosis is clinical; removal via electrodissection, liquid nitrogen, or laser is possible, though recurrence is high.

Glomus tumors are painful under-nail lesions formed by glomus bodies, benign with rare malignant variant; pain is triggered by temperature or touch, diagnosed by biopsy, and surgery cures.

Identify pyogenic granuloma as a red, vascular lesion that resembles a granuloma but is not granulomatous tissue. Bleed easily after trauma or pregnancy, and treat with excision or laser therapy.

Growing rapidly in infancy and appearing reddish due to capillary tissue, strawberry hemangiomas are benign vascular lesions that spontaneously regress over years and may occur in any organ.

Allergic contact dermatitis is eczema triggered by direct contact with an allergen or irritant, causing red, itchy, and blistered skin confined to the touched area, via type four hypersensitivity.

Identify atopic dermatitis as eczema, a type one hypersensitivity with IgE, facial onset in infancy, axillary involvement later, and links to asthma, allergic rhinitis, and flowering gene–related skin barrier dysfunction.

Identify arterial ulcers from peripheral artery disease and atherosclerosis, punched-out on distal toes or shin with severe pain and signs of arterial insufficiency; screen for abdominal aorta and coronary arteries.

Identify neurogenic ulcers from peripheral sensory loss, especially on heels, metatarsal heads, or sacral areas; ulcers are deep with inward edges, no pain, and show claw toes or Charcot joints.

Identify venous ulcers as the result of venous insufficiency with slow flow, ankle to mid-calf, presenting shallow, irregular borders with exudate, mild to moderate pain, and varicose veins, edema, dermatitis.