Dermatology Treatment

Acne vulgaris

Presentation: Comedones, inflammatory papules/pustules/nodules; face/chest/back. Treatment: Topical retinoids (tretinoin) + benzoyl peroxide; mild: topical antibiotics (clindamycin); moderate: add oral doxycycline/minocycline; severe: isotretinoin.

Cystic acne

Presentation: Large, painful, deep nodules and cysts; scarring common; “nodulocystic acne”. Treatment: Oral isotretinoin (Accutane) – gold standard; intralesional triamcinolone for acute flares; avoid oral antibiotics alone.

Adult female acne

Presentation: Inflammatory papules on lower face, jawline, chin; “hormonal pattern”; flares premenstrually. Treatment: First-line: topical retinoids + benzoyl peroxide; add spironolactone or oral contraceptives (if no contraindications); doxycycline for inflammatory flares.

Steroid acne

Presentation: Monomorphous papules/pustules on trunk/shoulders after systemic/topical steroid use. Treatment: Discontinue steroids if possible; topical retinoids + benzoyl peroxide; oral antibiotics if needed.

Recurrent staphylococcal folliculitis

Presentation: Recurrent crops of pruritic pustular follicles; buttocks/extremities/beard; nasal Staph carrier. Treatment: Mupirocin intranasal (for nasal carriage) + topical clindamycin/benzoyl peroxide; severe: oral doxycycline/TMP-SMX; avoid shaving.

Perioral dermatitis

Presentation: Papules/pustules/erythema around mouth; “spares vermilion border”. Treatment: Stop topical steroids (common trigger); first-line: topical metronidazole or topical erythromycin; oral doxycycline/minocycline for refractory cases.

Acne rosacea

Presentation: Central facial erythema, telangiectasias, papules/pustules; “no comedones”; flushing triggers. Treatment: Avoid triggers (sun, alcohol, spicy food); topical metronidazole, azelaic acid, or ivermectin; oral doxycycline (subantimicrobial dose) for papules/pustules; laser for telangiectasias.

Rhinophyma

Presentation: Lobulated bulbous enlargement of nose; sebaceous gland hyperplasia; “late complication of rosacea”. Treatment: Surgical: CO2 laser, dermabrasion, or scalpel sculpting; isotretinoin may slow progression; no medical reversal.

Hidradenitis suppurativa

Presentation: Painful deep nodules/abscesses/sinus tracts in axillae/groin/inframammary/perianal; chronic recurrent. Treatment: Mild: topical clindamycin; moderate: oral doxycycline ± rifampin; severe: adalimumab (TNF inhibitor); surgery: deroofing, excision; weight loss, smoking cessation.

Acne keloids nuchae

Presentation: Firm pruritic keloidal papules/plaques on posterior neck/occiput; “post-folliculitis”; common in Black males. Treatment: Intralesional triamcinolone (first-line); topical retinoids; laser; surgical excision with post-op radiation (high recurrence).

Epidermal inclusion cyst (EIC)

Presentation: Firm round mobile flesh-colored nodule with central punctum; “cheesy keratin debris” when ruptured. Treatment: Incision and drainage if infected; complete surgical excision (remove entire cyst wall) for definitive treatment.

Pilar cyst (trichilemmal cyst)

Presentation: Firm smooth often multiple nodules on scalp; “no central punctum”; familial. Treatment: Surgical excision (intact removal); often elective.

Steatocystoma multiplex

Presentation: Multiple small yellow-to-flesh-colored dermal nodules on chest/axillae/groin; “central punctum expresses oily fluid”. Treatment: Surgical excision; laser ablation; often for cosmetic concerns.

Pseudofolliculitis barbae

Presentation: Inflamed papules/pustules on beard area; “curved hairs re-enter skin”; curly/coarse hair; shaving exacerbates. Treatment: Stop shaving (grow beard); or shave with single-blade, electric razor, or depilatories; topical clindamycin + benzoyl peroxide; laser hair removal for refractory.

Dissecting cellulitis of scalp (folliculitis decalvans)

Presentation: Boggy interconnected nodules/abscesses on scalp; sinus tracts, scarring alopecia; “often with acne conglobata”. Treatment: Oral isotretinoin (first-line); oral antibiotics (doxycycline + rifampin); TNF inhibitors (adalimumab) for severe.

Pseudomonas folliculitis (hot tub)

Presentation: Pruritic erythematous papules/pustules “hours to days after hot tub/spa use”; spares palms/soles/face. Treatment: Self-limited (resolves in 7-10 days); no antibiotics typically; for severe: ciprofloxacin.

Pseudomonas cellulitis

Presentation: Erythematous edematous tender plaque; “after nail puncture through shoe”; may have greenish exudate. Treatment: Surgical debridement (remove foreign body); antibiotics: ciprofloxacin or levofloxacin; antipseudomonal beta-lactam (cefepime, piperacillin-tazobactam) for severe.

Pseudomonas toe web infection

Presentation: Maceration, greenish discoloration, malodor in toe webs (3rd-4th); “occlusive footwear, hyperhidrosis”. Treatment: Keep feet dry; topical aluminum chloride (antiperspirant); topical silver sulfadiazine or acetic acid soaks; oral ciprofloxacin if severe.

Beta hemolytic strep skin infection

Presentation: Rapidly spreading erythema, warmth, tenderness; erysipelas or cellulitis; Group A or B; “lymphangitis possible”. Treatment: Erysipelas: oral penicillin or amoxicillin; cellulitis: cephalexin, clindamycin, or doxycycline (if MRSA risk); severe: IV penicillin + IV clindamycin or ceftriaxone.

Impetigo contagiosum (non-bullous)

Presentation: Honey-colored crusted plaques on face/extremities; “often perioral”; highly contagious; children. Treatment: Topical mupirocin (limited disease); oral cephalexin or dicloxacillin (extensive); clindamycin if MRSA suspected.

Bullous impetigo

Presentation: Flaccid thin-walled bullae that rupture leaving collarette of scale; “Staph aureus toxin”; often in infants. Treatment: Similar to non-bullous: topical mupirocin for mild; oral cephalexin, clindamycin, or TMP-SMX for extensive; keep lesions clean.

Erysipelas

Presentation: Raised, sharply demarcated, bright red, indurated plaque; “face or lower leg”; fever, chills; Group A Strep. Treatment: Oral penicillin or amoxicillin (mild); IV penicillin G or ceftriaxone (severe); elevation, cool compresses.

Cellulitis

Presentation: Warm, erythematous, poorly demarcated, edematous area; tender; “no sharp border”; systemic symptoms possible. Treatment: Mild: oral cephalexin, clindamycin (if MRSA), or doxycycline; severe: IV vancomycin + cefazolin or ceftriaxone; elevation, treat underlying tinea pedis.

Blistering distal dactylitis

Presentation: Tense bullae on volar fat pad of finger; Group A Strep or Staph; “often children”. Treatment: Incise and drain bulla; oral antibiotics (cephalexin or amoxicillin-clavulanate); topical mupirocin.

Trichomycosis axillaris

Presentation: Yellow/black/red nodular concretions on axillary/pubic hair; Corynebacterium; “asymptomatic”. Treatment: Shave affected hair; topical clindamycin or erythromycin; topical benzoyl peroxide; aluminum chloride for hyperhidrosis.

Erythrasma

Presentation: Well-demarcated brown-red dry scaly patches in intertriginous areas; “coral-red fluorescence under Wood’s lamp”. Treatment: Topical miconazole, clotrimazole, or erythromycin; oral erythromycin or tetracycline for extensive; keep area dry.

Pitted keratolysis

Presentation: Multiple shallow “punched out” pits on pressure points of soles; foul odor; “occlusive footwear, hyperhidrosis”. Treatment: Topical clindamycin or erythromycin; topical benzoyl peroxide; aluminum chloride for hyperhidrosis; change socks/shoes.

Measles (rubeola)

Presentation: Prodrome of cough, coryza, conjunctivitis (3 Cs); Koplik spots; erythematous maculopapular rash face→downward. Treatment: Supportive (hydration, antipyretics); vitamin A (reduces morbidity/mortality); isolation; post-exposure vaccine or IG within 72 hours.

Mumps

Presentation: Parotitis (unilateral or bilateral); tender swelling of parotid glands; “may have orchitis, aseptic meningitis”. Treatment: Supportive (analgesics, antipyretics, ice packs); isolation; avoid acidic foods; IV fluids if unable to swallow.

Rubella (German measles)

Presentation: Lymphadenopathy (postauricular, suboccipital); pink maculopapular rash face→down, resolves in 3 days; “arthralgia in adults”. Treatment: Supportive; isolation (avoid pregnant women); congenital rubella syndrome prevention via vaccination.

Roseola (HHV-6/7)

Presentation: High fever 3-5 days, then defervescence with abrupt onset of pink maculopapular rash on trunk/neck; “infants/toddlers”. Treatment: Supportive (fever control, hydration); seizures (febrile) – benzodiazepines; benign self-limited.

Parvovirus B19 (fifth disease)

Presentation: “Slapped cheek” facial rash, then lacy reticular rash on extremities; “arthralgia”; aplastic crisis in hemolytic anemias. Treatment: Supportive (antihistamines for pruritus, NSAIDs for arthralgia); IVIG for chronic infection (immunocompromised); transfusion for aplastic crisis.

Coxsackie virus (hand-foot-mouth)

Presentation: Vesicles on palms, soles, oral mucosa (ulcers); fever; “often children”; also herpangina. Treatment: Supportive (fever/pain control, hydration); topical oral anesthetics (viscous lidocaine for older children, not infants); avoid dehydration.

Varicella zoster (chickenpox)

Presentation: Pruritic vesicles on erythematous base; “dew drop on a rose petal”; crops over 3-5 days; all stages present. Treatment: Supportive (calamine lotion, antihistamines, acetaminophen, NOT aspirin); acyclovir (if severe, adult, or immunocompromised); varicella vaccine post-exposure.

Herpes zoster (shingles)

Presentation: Unilateral dermatomal grouped vesicles on erythematous base; “pain, burning, paresthesia before rash”; postherpetic neuralgia. Treatment: Antiviral (acyclovir, valacyclovir, famciclovir) within 72 hours; analgesics (gabapentin, pregabalin, opioids for PHN); zoster vaccine.

Verruca vulgaris (common wart)

Presentation: Hyperkeratotic rough papule with thrombosed capillaries (“black dots”); fingers/hands/knees. Treatment: Salicylic acid (OTC); cryotherapy (liquid nitrogen); cantharidin; laser; bleomycin; (often self-limited in children).

Filiform wart

Presentation: Thin, finger-like projections; “face (eyelids, nose, lips)”; same HPV type as common wart. Treatment: Shave excision, curettage, cryotherapy, or laser (avoid scarring on face); topical retinoids.

Flat warts (verruca plana)

Presentation: Small smooth flat-topped flesh-colored papules; “face, dorsa hands, shins”; linear spread (Koebner phenomenon). Treatment: Topical tretinoin; topical imiquimod; cryotherapy; laser; often resolve spontaneously.

Plantar wart

Presentation: Endophytic painful “mosaic” pattern; “interrupts skin lines”; tender with lateral compression. Treatment: Salicylic acid plaster; cryotherapy; laser; surgical excision (last resort due to scarring); duct tape (weak evidence).

Periungual wart

Presentation: Hyperkeratotic fissured papules around nail plate; “may disrupt cuticle and nail growth”. Treatment: Cryotherapy; salicylic acid; laser; intralesional bleomycin or Candida antigen; protect nail matrix.

Condyloma acuminata (genital warts)

Presentation: Fleshy cauliflower-like exophytic papules/plaques in anogenital region; HPV 6, 11. Treatment: Patient-applied: podofilox, imiquimod, sinecatechins; provider-applied: cryotherapy, TCA, surgical excision; HPV vaccine prevents.

Bowenoid papulosis

Presentation: Multiple brown-to-violaceous papules in genital area; “histology like Bowen’s disease (SCC in situ)”; HPV 16. Treatment: Excision (monitor margins); laser ablation; topical 5-FU or imiquimod; follow-up due to malignant potential.

Molluscum contagiosum

Presentation: Dome-shaped pearly umbilicated papules with central keratotic plug; “children or sexually active adults”. Treatment: Often self-limited (months-years); cantharidin, cryotherapy, curettage, topical tretinoin or imiquimod.

Thrush (oral candidiasis)

Presentation: White curd-like plaques on buccal mucosa/tongue/palate; “scrapes off leaving raw erythematous base”. Treatment: Nystatin suspension (swish & swallow) or clotrimazole troches; fluconazole (single or 7-14 days); treat underlying immunodeficiency.

Angular cheilitis

Presentation: Erythema, fissuring, scaling at corners of mouth; “Candida + Staph”; associated with drooling, dentures, nutritional deficits. Treatment: Topical clotrimazole + hydrocortisone; topical mupirocin if bacterial; correct nutritional deficiencies (B vitamins, iron); denture adjustment.

Vulvovaginal candidiasis

Presentation: Vaginal itching, burning, thick white “cottage cheese” discharge; “dysuria, dyspareunia”. Treatment: Topical azoles (miconazole, clotrimazole) OTC; oral fluconazole (150 mg single dose); treat partner if recurrent.

Candida balanitis

Presentation: Erythema, white patches, small pustules on glans penis; “pruritic”; uncircumcised men, poorly controlled diabetes. Treatment: Topical clotrimazole or miconazole; oral fluconazole if severe; circumcision for recurrent; glucose control.

Diaper dermatitis (candida)

Presentation: Bright red confluent erythema in diaper area; “satellite pustules”; spares skin folds; after antibiotics. Treatment: Topical nystatin or clotrimazole; barrier cream (zinc oxide); frequent diaper changes; avoid occlusive plastic pants.

Erosio interdigitalis blastomycetica

Presentation: Weeping erythematous macerated lesions in interdigital webs (3rd-4th fingers); “Candida”; wet workers. Treatment: Topical clotrimazole or miconazole; keep hands dry; topical drying agent (aluminum chloride).

Tinea corporis (ringworm)

Presentation: Annular scaly plaque with central clearing and active raised border; “pruritic”; glabrous skin. Treatment: Topical allylamines (terbinafine) or azoles (clotrimazole) for 1-2 weeks; oral terbinafine or griseofulvin for extensive or immunocompromised.

Tinea pedis (athlete’s foot)

Presentation: Interdigital maceration, scaling, fissuring; “moccasin-type” dry scaling on soles; pruritic. Treatment: Topical terbinafine or clotrimazole (2-4 weeks); severe: oral terbinafine; keep feet dry, change socks, antifungal powder.

Tinea manus

Presentation: Unilateral dry scaling on palm and dorsal hand; “often with tinea pedis” (two feet-one hand syndrome). Treatment: Same as tinea pedis; oral terbinafine often required (thick skin on palm).

Tinea faciale

Presentation: Annular scaly erythematous plaque on face; “less distinct border than tinea corporis”; worsened by topical steroids. Treatment: Topical antifungal (terbinafine, clotrimazole) – avoid corticosteroids; oral antifungal if extensive or refractory.

Tinea cruris (jock itch)

Presentation: Erythematous scaly half-moon plaques in groin/inner thighs; “spares scrotum”; itchy, bilateral. Treatment: Topical terbinafine or clotrimazole (1-2 weeks); keep dry; avoid tight clothing; oral antifungal for severe.

Tinea capitis

Presentation: Scalp scaling, patchy alopecia with broken hairs (“black dots”); ± kerion. Treatment: Oral antifungal (terbinafine for Trichophyton, griseofulvin for Microsporum) for 4-8 weeks; selenium sulfide shampoo (reduce shedding); no topical monotherapy.

Kerion

Presentation: Boggy tender pustular scalp mass with alopecia; “severe inflammatory reaction to tinea capitis”; may scar. Treatment: Oral antifungal (same as tinea capitis) plus prednisone (for severe inflammation) to reduce scarring; avoid incision.

Onychomycosis

Presentation: Thickened yellow-brown crumbly opaque nail plate; subungual debris; “distal lateral onycholysis”. Treatment: Oral terbinafine (12 weeks fingernails, 12-16 weeks toenails) – most effective; topical ciclopirox or efinaconazole (less effective); laser (limited evidence).

Tinea versicolor

Presentation: Hypopigmented or hyperpigmented fine scaly macules on trunk/upper arms; “no pruritus”; KOH: “spaghetti and meatballs”. Treatment: Selenium sulfide shampoo (apply 10 min daily); topical ketoconazole or terbinafine; oral fluconazole (once weekly for 2 weeks) for extensive; recurrence common.

Sporotrichosis

Presentation: Subcutaneous nodules along lymphatics (lymphocutaneous); “after thorn/plant puncture”; “rose gardener’s disease”. Treatment: Oral itraconazole (first-line, 3-6 months); severe or disseminated: amphotericin B; topical heat (adjunct).

Erythema multiforme

Presentation: Target (iris) lesions with concentric rings; hands/feet/elbows/knees; “may have oral mucosa”; post-herpes or drug-induced. Treatment: Treat underlying cause (acyclovir for HSV); supportive care; oral antihistamines; topical steroids; severe: systemic steroids controversial.

Erythema nodosum

Presentation: Tender erythematous warm subcutaneous nodules on shins; “no ulceration”; associated with strep, sarcoid, IBD, drugs. Treatment: Treat underlying cause (e.g., antibiotics for strep); NSAIDs; potassium iodide; colchicine; rest, leg elevation.

Rickettsial illness (e.g., RMSF)

Presentation: Fever, headache, myalgia; rash starts on wrists/ankles, becomes petechial; “history of tick bite”. Treatment: Doxycycline (even in children, even before rash); treatment should NOT be delayed for lab confirmation.

Drug eruption (generalized)

Presentation: Morbilliform (measles-like) rash starting on trunk, spreading to extremities; “pruritic”; 1-2 weeks after drug start. Treatment: Stop offending drug (if possible); antihistamines; topical steroids; severe or persistent: oral steroids; monitor for SJS/TEN.

Seborrheic keratosis

Presentation: “Stuck-on” appearance, waxy brown-to-black plaque with verrucous surface; “common on trunk/face of older adults”. Treatment: No treatment required; removal: cryotherapy, curettage, shave excision, laser (cosmetic).

Dermatosis papulosa nigra

Presentation: Multiple small smooth dark brown to black papules on cheeks/periorbital; “common in Black individuals”; variant of seborrheic keratosis. Treatment: Electrodessication, curettage, or laser (cosmetic); no treatment needed.

Stucco keratosis

Presentation: Small dry rough white-to-gray papules on lower legs/ankles/dorsal feet; “stuck-on appearance”. Treatment: Usually observation; cryotherapy or curettage if bothersome.

Skin tag (acrochordon)

Presentation: Soft flesh-colored or hyperpigmented pedunculated papule; “neck, axillae, groin”; obesity, diabetes. Treatment: Snip excision, cryotherapy, or electrodessication.

Dermatofibroma

Presentation: Firm hyperpigmented papule with “dimple sign” (central depression when pinched); most common on legs. Treatment: Observation (benign); surgical excision if symptomatic (pain, itching) – recurrence rate low.

Sebaceous hyperplasia

Presentation: Yellowish soft umbilicated papule with central dell; “forehead, cheeks”; middle-aged/older adults. Treatment: Observation; cryotherapy, electrodessication, laser (CO2, pulsed dye), or topical retinoids for cosmetic.

Lipoma

Presentation: Soft mobile subcutaneous nodule; “painless”; most common on trunk and proximal extremities. Treatment: Observation; surgical excision if large, painful, or cosmetic.

Syringoma

Presentation: Multiple small flesh-colored firm dermal papules; “lower eyelids, cheeks”; more common in women; benign eccrine duct tumor. Treatment: Observation; laser (CO2, erbium) or electrodessication for cosmetic; high recurrence.

Neurofibroma

Presentation: Soft flesh-colored papule or pedunculated lesion; “buttonhole invagination”; neurofibromatosis type 1. Treatment: Observation; surgical excision if painful, growing, or malignant transformation suspected (rare).

Hypertrophic scar / keloid

Presentation: Raised erythematous pruritic scar within original wound borders (hypertrophic) or beyond (keloid); “more common in dark skin”. Treatment: Intralesional triamcinolone (first-line); silicone gel/sheeting; cryotherapy; laser; surgical excision (keloids often recur, need post-op radiation).

Keratoacanthoma

Presentation: Rapidly growing dome-shaped nodule with central keratotic crater; “resolves spontaneously”; mimics SCC. Treatment: Surgical excision (preferred, to rule out SCC); intralesional methotrexate or 5-FU; observation (controversial).

Pustular psoriasis (generalized)

Presentation: Sterile pustules on erythematous base; fever, malaise; “triggered by steroids or infection”; medical emergency. Treatment: Hospitalize; withdraw systemic steroids (slowly); acitretin, cyclosporine, or infliximab; supportive care.

Asteatotic eczema

Presentation: Dry cracked “crazy paving” appearance on lower legs; “low humidity, winter, over-washing”. Treatment: Topical emollients (petrolatum, ceramides); topical mid-potency steroid for inflammation; avoid hot water, harsh soaps.

Lichen simplex chronicus

Presentation: Thick lichenified plaques with accentuated skin lines; “intense pruritus from chronic scratching”; neck/ankles/scalp. Treatment: Break scratch-itch cycle: high-potency topical steroids with occlusion; oral antihistamines (sedating at night); behavioral modification.

Prurigo nodularis

Presentation: Multiple firm hyperpigmented excoriated nodules on extensor extremities; “intense pruritus”; chronic scratching. Treatment: High-potency topical steroids with occlusion; intralesional triamcinolone; oral antihistamines; phototherapy (NB-UVB); off-label: dupilumab, naltrexone.

Irritant dermatitis

Presentation: Sharply demarcated erythematous chapped painful rash at exposure site; “chemical/irritant” (e.g., hand sanitizers). Treatment: Avoid irritant; barrier creams (petrolatum); topical steroids for inflammation; moisturizers.

Epidermolysis bullosa (simplex)

Presentation: Blisters after minor friction/trauma; hands/feet; “healing without scarring”; autosomal dominant. Treatment: Supportive: protect skin, avoid trauma, lancing blisters (sterile), non-adherent dressings; genetic counseling.

Bowen’s disease (SCC in situ)

Presentation: Well-demarcated erythematous scaly plaque; “slow-growing”; any skin or mucosa. Treatment: Surgical excision (gold standard); cryotherapy; topical 5-FU or imiquimod; photodynamic therapy; curettage.

Linear epidermal nevus

Presentation: Streaky warty skin-colored or brown papules along Blaschko’s lines; “present at birth or early childhood”. Treatment: Observation; surgical excision or laser for cosmetic or symptomatic; monitor for secondary tumors (rare).

Becker’s nevus

Presentation: Unilateral hyperpigmented hairy patch on shoulder/chest/back; “appears in adolescence”; smooth muscle hamartoma. Treatment: Observation; laser for hyperpigmentation or hair (difficult to treat).

Nevus sebaceous

Presentation: Yellow-orange waxy hairless plaque on scalp or face; “linear or oval”; present at birth; may develop secondary tumors. Treatment: Prophylactic surgical excision (controversial; some recommend pre-pubertal due to low tumor risk); observe with annual skin exam.

Mongolian spot

Presentation: Large blue-gray ill-defined macule in lumbosacral area; “present at birth”; fades by childhood; dark-skinned infants. Treatment: None (benign, resolves spontaneously); reassurance.

Nevus of Ota

Presentation: Blue-gray hyperpigmentation in trigeminal nerve distribution (periorbital, cheek, sclera); “more common in Asian females”. Treatment: Observation; laser (Q-switched ruby/nedymium) for cosmetic; monitor for glaucoma (eye exam) and rare melanoma.

Blue nevus

Presentation: Small blue-to-black dome-shaped papule; “dorsal hands and feet”; benign dermal melanocytic nevus. Treatment: Observation; excise if changes, atypical features, or cosmetic.

Nevus depigmentosus

Presentation: Stable well-defined hypopigmented patch present at birth/early childhood; “does not repigment”; no preceding inflammation. Treatment: Observation; no effective repigmentation; cosmetic camouflage; avoid sun.

Nevus spilus (speckled lentiginous nevus)

Presentation: Tan background macule with darker brown macules/papules within; “congenital or acquired”. Treatment: Observation; excise if atypical change or melanoma suspected.

Halo nevus

Presentation: Nevus surrounded by depigmented halo; “often regresses spontaneously”; multiple halos → vitiligo or melanoma risk. Treatment: Observation (benign, involution over years); dermatology follow-up if multiple, adult onset, or asymmetric/irregular nevus.

Pellagra

Presentation: Niacin deficiency: dermatitis (photosensitive, Casal necklace), diarrhea, dementia; “roughened hyperpigmented skin on sun-exposed areas”. Treatment: Niacin (nicotinamide) supplementation; treat underlying cause (alcoholism, malnutrition, carcinoid); sun protection.

Melasma

Presentation: Symmetrical brown to gray-brown patches on cheeks/forehead/upper lip; “pregnancy mask”; sun, OCPs, pregnancy. Treatment: Sunscreen (broad spectrum, tinted with iron oxide); topical hydroquinone, tretinoin, azelaic acid; chemical peels, laser; discontinue OCPs.

Polymorphic light eruption

Presentation: Itchy papules/vesicles/plaques on sun-exposed skin hours to days after UV exposure; “resolves without scarring”. Treatment: Sun protection; topical corticosteroids; oral antihistamines; phototherapy (hardening); severe: hydroxychloroquine, prednisone.

Actinic prurigo

Presentation: Papules, nodules, excoriations on sun-exposed skin; “with cheilitis”; Native American populations. Treatment: Sun protection; topical steroids; oral thalidomide (refractory); phototherapy; avoid UV.

Chronic actinic dermatitis

Presentation: Persistent eczematous lichenified plaques on sun-exposed areas; “older men”; photoallergic to UV or visible light. Treatment: Sun protection (physical blockers); topical steroids; oral prednisone for flares; immunosuppressants (azathioprine, mycophenolate) for severe; phototherapy.

Phototoxic drug eruption

Presentation: Exaggerated sunburn in sun-exposed areas within hours of medication (doxycycline, thiazides, amiodarone); “no immune reaction”. Treatment: Stop offending drug; sun protection; topical corticosteroids; oral antihistamines; cool compresses.

Phytophotodermatitis

Presentation: Linear blistering then hyperpigmented streaks after plant contact (lime, celery) + UV; “pain before itch”. Treatment: Cool compresses; topical corticosteroids; avoid sun; hyperpigmentation fades spontaneously (months).

Poikiloderma of Civatte

Presentation: Reticulated hyperpigmented atrophic telangiectatic skin on lateral neck/chest; “chronic sun damage in fair-skinned women”. Treatment: Sun protection; laser (IPL, pulsed dye) for telangiectasias; topical retinoids; cosmetic camouflage.

Solar lentigo (age spot)

Presentation: Well-defined brown flat macule on sun-exposed skin (face, hands); “no malignant potential”; increases with age. Treatment: None (benign); cosmetic: cryotherapy, laser, topical hydroquinone, tretinoin; sun protection prevents new ones.

Idiopathic guttate hypomelanosis

Presentation: Small (2-5mm) porcelain-white well-defined macules on sun-exposed shins/forearms; “common in older adults”. Treatment: None (benign); no effective repigmentation; sun protection; cosmetic camouflage.