Diagnostic Algorithm

I. No apparent lesions (symptoms only)

 

    Pruritus

1. Pruritus

    Pain

2. Pain, paresthesia, anesthesia

 

 

II. Skin-colored lesions

 

     A. Epidermis intact and attached

 

          Scale absent

3. Smooth skin-colored lesions

          Scale present

4. Scaling skin-colored lesions

     B. Epidermis lifted (blisters)

 

          Blister fluid clear

5. Vesiculobullous lesions

          Blister fluid white or yellow-white

6. Pustular lesions

     C. Epidermis missing

 

          Defect shallow (epidermis)

7. Erosions

          Defect deep (dermis)

8. Ulcers

 

 

III. Non-blanchable, abnormally-colored lesions                         

 

     A. Melanin pigment

 

          Hypopigmentation

9. White lesions

          Hyperpigmentation

10. Brown or black lesions

     B. Heme pigment

 

           Non-palpable

11. Non-palpable purpuras

           Palpable

12. Palpable purpuras

     C. Other pigments

 

           Blue-gray

13. Blue-gray lesions

           Yellow

14. Yellow lesions

 

 

IV. Blanchable, red (Inflammatory) lesions

 

     A. Non-scaling red lesions

 

         Flat and flat-topped lesions

15. Vascular reactions

         Rounded and slope-shouldered lesions

16. Red papules and nodules

     B. Scaling, red lesions

 

          Epithelium intact

17. Papulosquamous lesions

          Epithelium disrupted

18. Eczematous lesions

functional origin

anxiety (especially OCD), depression (esp. elderly)

systemic disorders

hepatic d. (biliary cirrhosis, obstructive d.), iron deficiency,lymphoma (Hodgkin’s), polycythemia vera, pregnancy, renal d., thyroid d.

unapparent skin conditions

AIDS, fiberglass dermatitis, mastocytosis, pediculosis (pubic, head, body), scabies, sweat retention (esp. atopics), xerosis (atopy, ichthyosis, excess bathing)

absent lesions

localized chronic pain s. (glossodynia, vulvodynia, anodynia), neuralgia, post-herpetic neuralgia, reflex sympathetic dystrophy, trigeminal neuralgia

absent pain

congenital absence, leprosy, peripheral neuropathy (esp. diabetes), syringomyelia

lesion-associated

angioleiomyoma, angiolipoma, eccrine spiradenoma, glomus tumor, leiomyoma, neurilemmoma, neuroma

paresthesia

formication (“crawling” sensation in skin) in true infestation & delusions

cysts

epidermoid, mucinous, pilar, synovial

edema & pseudo-edema

angioedema, chronic genital edema, eosinophilic fasciitis, lymphedema, Melkersson-Rosenthal s., scleredema, scleromyxedema

flat & atrophic lesions

lipoatrophy, lipodystrophy, pitted keratolysis, striae

papules, nodules

BCC, chondrodermatitis nodularis, closed comedones, lipomas, molluscum contagiosum, neurofibroma, nevi (intradermal, neural), pearly penile papules, rhinophyma, scars (hypertrophic, keloid), SCC, sebaceous hyperplasia, skin tags (achrocordons), warts

rare lesions

accessory tragus, acrodermatitis chronica atrophicans, anetoderma, arsenical keratoses, basal cell nevus s., calcinosis cutis, connective tissue nevus, Cowden’s s., cylindroma, dermoid cyst, Dupuytren’s contracture, erythropoietic protoporphyria, fibroma, follicular mucinosis, knuckle pads, lipoidproteinosis, neuroma, nevus sebaceus, osteoma cutis, palmar crease keratoses, palmar/plantar keratoderma, sarcoma, syringoma, thyroglossal cyst, tophi, trichoepithelioma

papules & nodules

actinic keratosis, callous, corn, keratoacanthoma, SCC, seborrheic keratosis, verruca

plaques & disseminated disease

epidermal nevus, ichthyosis, nevus sebaceus, porokeratosis of Mibelli, post-inflammatory desquamation & exfoliation, tinea manum, tinea pedis, xerosis

uncommon, rare

acrokeratoelastoidosis, acrokeratosis verruciformis, Cowden’s s., disseminated actinic porokeratosis, elastosis perforans serpiginosum, elephantiasis nostra verrucosa, epidermodysplasia verruciformis, hyperkeratosis lenticularis perstans, knuckle pads, Kyrle’s d., perforating folliculitis, stucco keratoses, surfer’s nodule

vesicular, common

dyshidrosis (pompholyx), herpes simplex, herpes zoster, id reaction, molluscum contagiosum, scabies, tinea pedis (vesicular), vesicular insect bites

vesicular, uncommon & rare

chronic bullous disease of childhood, dermatitis herpetiformis, eczema herpeticum & vaccinatum, Grover’s d., hand foot & mouth d., herpes gestationis, hidrocystoma, incontinentia pigmenti, intraepidermal IgA disease, linear IgA d., lymphangioma circumscriptum, pityriasis lichenoides

bullous, common

burns, bullous impetigo, contact dermatitis, friction blisters

bullous, uncommon

bullous disease of dialysis, bullous hemorrhagic pyoderma gangrenosum, chronic bullous disease of children, coma blisters, diabetic bullous d., epidermolysis bullosa, epidermolysis bullosa acquisita, erysipeloid, erythema multiforme, fixed drug eruption, linear IgA disease, milker’s nodule, necrotizing fasciitis, orf, pemphigoid, pemphigus, porphyria

common

acne vulgaris, acne conglobata, candidiasis, erythema toxicum neonatorum, folliculitis, keratosis pilaris, perioral dermatitis, pyoderma faciale, rosacea, stye

uncommon

acne keloidalis, acne necrotica miliaris, acrodermatitis continua, Behçet’s d., bowel bypass s., chloracne, chronic gonococcemia, Crohn’s d., dissecting cellulitis, eosinophilic folliculitis, folliculitis decalvans, hidradenitis suppurativa, impetigo herpetiformis, infantile acral pustulosis, intraepidermal neutrophilic IgA dermatosis, myeloma, pityrosporum folliculitis, psoriasis, pustular dyshidrosis, pustular psoriasis, pustulosis palmaris et plantaris, steroid acne, subcorneal pustular dermatosis, transient neonatal pustular melanosis, ulcerative colitis

common

candidiasis, excoriation, impetigo, unroofed vesiculobullous & pustular lesions

uncommon

acrodermatitis enteropathica, glucagonoma s., SSSS, TEN

common

aphthous ulcers, arteriosclerotic, BCC, chondrodermatitis nodularis, decubitus, gangrenous ulcers, neuropathic, SCC, stasis, traumatic

uncommon

actinomycosis, amebiasis, anthrax, aplasia cutis congenita, Bart’s s., chancroid, Churg & Strauss d., Crohn’s d. of skin, dental sinus, ecthyma, factitial, focal dermal hypoplasia, fungal infection, hemoglobinopathies, herpes infection, chronic (immunosuppressed), congenital sinus, granuloma inguinale, keratoacanthoma, leishmaniasis, lymphoma, lymphomatoid papulosis, mycobacterial infection, nocardiosis, panniculitis, polyarteritis nodosum, pyoderma (blastomycosis-like), pyoderma (malignant), pyoderma gangrenosum, septicemic ulcers, spider bite, syphilis (primary), temporal arteritis, tularemia, Wegener’s d.

papules

acne vulgaris, calcinosis cutis, hair casts, keratosis pilaris, lichen nitidus, milia, molluscum contagiosum, nits, scars, sebaceous gland hyperplasia, tophus, white piedra

patches, plaques

albinism, atrophie blanche, chemically induced hypomelanosis, Degos’ d., halo nevus, hypomelanosis of Ito, hypopigmentation, idiopathic guttate hypomelanosis, leprosy, lichen sclerosis et atrophicus, morphea, piebaldism, pinta, pityriasis alba, poliosis, post-inflammatory sarcoid, scleroderma, tinea versicolor, tuberous sclerosis, vitiligo, yaws

mucous membrane

biting trauma, candidiasis, leukoplakia, lichen planus, lupus erythematosus, secondary syphilis, white hairy leukoplakia

generalized

Addison’s disease, cancer chemotherapeutic agents, dyskeratosis congenita, exfoliative erythrodermatitis, heavy metals, hemochromatosis, ichthyosis, MSH-related pigmentation in endocrine & malignant d., phenothiazines, porphyria, progeria, Rothmund-Thomson s., scleroderma, Whipple’s d., Wilson’s d.

macules, papules, nodules

acanthosis nigricans, acrochordon (skin tag), angiokeratoma, black piedra, Bowenoid papulosis, dermatofibroma, dermatosis papulosis nigra, freckles, lentigo, lentigo maligna, lentigo maligna melanoma, nevus (compound, junctional, intradermal), nevus (dysplastic), open comedone, pigmented BCC, seborrheic keratosis, urticaria pigmentosa

patches & plaques

acanthosis nigricans, acral lentiginous melanoma, Albright’s s., alkaptonuria, atrophoderma of Pasini & Pierini, Becker’s nevus, Berloque (furocoumarin) dermatitis, café-au-lait macules, café-au-lait like birthmarks, chloasma (melasma), confluent & reticulated papillomatosis, congenital pigmented nevus, Dowling-Degos’ disease, erythema ab igne, erythrasma, fixed drug eruption, incontinentia pigmenti (late), lentigo maligna, lentigo maligna melanoma, linear nevoid hypermelanosis, morphea, pigmentary demarcation lines (Futcher’s line), poikilodermatous pigmentation, postinflammatory hyperpigmentation, tinea nigra palmaris, tinea versicolor

ecchymotic

actinic purpura, amyloidosis, angioimmunoblastic lymphadenopathy, anticoagulant therapy, calciphylaxis, DIC, Gardner-Diamond s., intravascular coagulation defects (platelets, erythrocytes, coagulation proteins), necrotizing fasciitis, scurvy, steroid purpura, superficial hemorrhagic pyoderma gangrenosum, trauma, vasculitis (polyarteritis nodosa, lymphomatoid granulomatosis)

petechial (primarily)

bacteremia (staphylococcal, meningococcal, bacteria endocarditis), benign pigmented purpuras, black-dot toes & heels, dysproteinemia (cryoglobulinemia), histiocytosis X, hydrostatic petechiae (stasis), intravascular coagulation defects, medication (thiazides)

bacteremia

bacteria endocarditis, meningococcal, staphylococcal

non-vasculitic

angiokeratoma, cherry angioma, Kaposi’s sarcoma, pyogenic granuloma

rickettsia

RMSF, typhus

venulitis, arteritis

dysproteinemia, Henoch-Schönlein purpura, leukocytoclastic vasculitis, (hypersensitivity vasculitis, rheumatoid vasculitis)

macules, patches

atrophoderma of Pasini & Pierini, erythema dyschromicum perstans, fixed drug eruption, heliotrope eyelids (dermatomyositis), hemochromatosis, medication (antimalarials, gold, metals, minocycline, phenothiazines, silver), Mongolian spot, Nevus of Ito & Ota, osteoma cutis, tattoo (asphalt, foreign body, graphite, lead), venous lake

papules, nodules

acroangiodermatitis (arteriovenous fistula, pseudo-Kaposi’s disease), angiosarcoma, angiolymphoid hyperplasia, blue nevus, collagen vascular d., Glomus tumor, granuloma annulare, hemangioma (esp. cavernous & verrucous), hidrocystoma, Kaposi’s sarcoma (esp. classic), leukemia cutis, lichen planus, lymphoma cutis (esp. B-cell), pyogenic granuloma

macules, patches

amyloidosis, carotenemia, Fordyce condition (mucous membranes), jaundice, keratoderma of palms & soles, necrobiosis lipoidica diabeticorum, pseudoxanthoma elasticum, solar elastosis, xanthomas (palmar, plantar)

papules, plaques, nodules

amyloidosis, colloid milium, cyst, histiocytic lesion, juvenile xanthogranuloma, mastocytoma, nevus sebaceus, sebaceous hyperplasia, solar elastosis, tophus, xanthelasma, xanthoma (tendinous, tuberous)

diffuse, morbilliform

GVH, Kawasaki d., scarlet fever, SSSS, TEN (early erythema chronic migrans,), toxic shock s., viral exanthem (erythema infectiosum, roseola, rubella, rubeola)

gyrate, serpiginous, annular

creeping eruption elastosis perforans serpiginosum, erythema annulare centrifugum, erythema gyratum repens, erythema multiforme, granuloma annulare, sarcoid, SCLE

livedo pattern

antiphospholipid s. (lupus anticoagulant, Sneddon’s s.), cholesterol emboli, cutis marmorata telangiectatica, erythema ab igne, erythema infectiosum, large vessel vasculitis, poikiloderma (Civatte, collagen vascular disease, cutaneous lymphoma), polyarteritis

macular localized

acrocyanosis, BCC, Bowen’s d., face (lupus erythematosus, dermatomyositis, seborrheic dermatitis, photosensitivity reaction), fixed drug eruption, groin (intertrigo, erythrasma, tinea cruris, seborrheic dermatitis), hand (erythromelalgia, liver d., hereditary redness of the palm, chemotherapy), pernio, tinea versicolor

plaques

arthropod assault, cellulitis, erysipelas, erysipeloid, erythema elevatum diutinum, erythema multiforme, erythema nodosum, fixed drug eruption, granuloma faciale, hypocomplementemic vasculitis, juvenile rheumatoid arthritis, nodular vasculitis, panniculitis, PUPPP, relapsing polychondritis, Sweet’s s., Well’s cellulitis

telangiectatic

angioma serpiginosum, ataxia telangiectasia, erythema ab igne, essential telangiectasia, poikilodermatous conditions, radiodermatitis, telangiectasia of collagen vascular disease (CREST s.), TMEP, unilateral nevoid telangiectasia

transient erythema

anaphylactic reaction, contact urticaria, cutis marmorata, dermographism, erythema marginatum urticaria, flushing (carcinoid, emotional, mastocytosis, medications, pheochromocytoma), physical urticaria

papules

arthropod assault, cherry angioma, CNCH, coral & marine animal contact, diaper granuloma, elastosis perforans serpiginosum, eosinophilic folliculitis, eruptive xanthoma, foreign body granuloma, Gianotti-Crosti s., Gottron’s papules, granuloma annulare, Grover’s d., Kaposi’s sarcoma, lymphomatoid papulosis, mites, multicentric reticulohistiocytosis, papular urticaria, pityriasis lichenoides, pityriasis rosea, pityrosporum folliculitis, pyogenic granuloma, sarcoid, scabies, secondary stye & hordeolum, syphilis

nodules, plaques

acne conglobata, acne cyst, angiolymphoid hyperplasia with eosinophilia, angiosarcoma, arthropod assault, carbuncle, cylindroma, dissecting cellulitis, erythema elevatum diutinum, erythema nodosum, furuncle, granuloma annulare, hemangioma, hidradenitis suppurativa, inflamed cyst, Kaposi’s sarcoma, lupus erythematosus, lymphocytic infiltrate of Jessner, lymphoma & leukemia cutis, milker’s nodule, mycobacterial infection, myiasis, nodular vasculitis (erythema induratum), orf, panniculitis, polymorphous light eruption, pseudolymphoma, pyoderma faciale, rheumatoid nodules, sarcoma, sporotrichosis, Sweet’s s., vasculitis (esp. polyarteritis nodosum)

papules

lichen planus, pityriasis lichenoides, pityriasis rosea, psoriasis, secondary syphilis, viral exanthem

plaques

actinic reticuloid, Basex s., Bowen’s d., Darier’s d., ichthyosis, ILVEN, keratosis lichenoides chronica, lichen striatus, lupus erythematosus, mycosis fungoides, Pagetoid reticulosis, parapsoriasis, pellagra, photosensitivity eruptions, pityriasis rubra pilaris, psoriasis, Reiter’s s., superficial BCC, tinea (capitis, corporis, cruris, pedis)

prominent excoriation

atopic dermatitis, dermatitis herpetiformis, dyshidrotic eczema, exfoliative erythrodermatitis, lichen simplex chronicus, neurodermatitis, scabies, stasis dermatitis

minimal excoriation

acrodermatitis enteropathica, actinic reticuloid, allergic contact dermatitis, asteatotic eczema, autoeczematization, Darier’s d., external otitis, glucagonoma s., Hailey-Hailey d., histiocytosis X, ILVEN, impetigo, infectious eczematoid dermatitis, irritant contact dermatitis, juvenile palmar-plantar dermatitis, Leiner’s d., lichen striatus, nummular eczema, Paget’s d., perioral dermatitis, photosensitivity s., seborrheic dermatitis, winter itch, xerotic eczema