Ddx Chart Part 4

1 Anthropods SCABIES

PEDICULOSIS CAPITIS (head lice) eggs and their casings (nits) attach to the hair shaft and eggs hatch in approx 10 days

Distribution

fingerwebs, wrists, groin, sides of hands and feet, torso, breasts

scalp, especially at lateral and posterior aspects

Lesions

Linear or waxy ridges 0.5 -1.0 mm long (where mite has burrowed) with pustules, vesicles and nodules ( not always readily seen)

primary papules with secondary excoriations, erythema, crust

Presentation

PEDICULOSIS PUBIS (crabs/pubic/body lice)

can occur anywhere on the body

papules or macules with secondary blue grey macules (bite sites)

usually expands to more than 5 cm diameter flu-like symptoms often accompany skin lesion for a few days to 6 weeks after tick bite

cervical lymph nodes may be enlarged

Symptom

Intense Pruritis→(hallmark of scabies) d/t hypersensitivity rxn to mite & its feces

severe pruritis usually of sides and back of scalp

severe itching in pubic area less often axillary area or eyelashes, with eczematization and possible secondary infection

Dx

scabies preparation -find a burrow on hands or feet; burrow is scraped at its base

based on careful observation of the scalp

nits usually seen attached to hair shafts

lice may be seen but more common to see nits attached to the hair shaft

lice may appear as small moving freckles, and brown specks on underwear are mite feces

nits can be distinguished from hair debris: nit has an intact shell casing totally surrounding it, allowing to slide up and down along the hair shaft when combed

magnifying glass helpful

material is on glass slide and covered with KOH, mineral oil -demonstrate mites, mite eggs or mite feces

characterized by an expanding erythematous macule or patch with central clearing at the site of a tick bite Erythema Migrans is initial skin manifestation; seen in 60 - 80 % of people with Lyme disease

Secondary erythema, crust and excoriation due to scratching Sign

LYME DISEASE

understand early manifestations as to prevent serious sequelae of Lyme disease (ie neurological – Bell’s palsy, encephalitis; cardiac: heart block; arthritis)

2 History

Duration DDx

Transmission: skin to skin contact;

or examined ie well attached Transmission: head to head contact or sharing infested combs, hats etc

Sexual activity

endemic area/activities ie camping, hiking, hunting

mites live only a few hours on fomites (bedding or clothing)

erythema migrans within 1 -2 months of tick bite

other family members often have similar symptoms

flu-like symptoms during summer months

Symptoms usually occur 3-6 weeks after the primary infestation 1.Insect Bites → confined to an area →itching dissipates

several weeks and resolves spontaneously 1.Normal tick bites → lesions aren’t bigger than 5 cm diameter and last less than 7 days

2. Eczema →flexor surfaces →family not affected

1.Seborrheic Dermatitis →won’t stick → scales are easily scraped, but nits are firmly attached to hair shaft and not easily removed

2. Folliculitis → pustules and crusting are scattered throughout the scalp, no nits

2.Cellulitis →localized heat & tenderness →no central clearing 3.Contact Dermatitis → pruritis predominates, along with progression to vesiculation → no systemic complaints 4.Tinea Corporis →also central clearing, but scaling 5.Spider Bite → pain and ulceration at site of bite are acute; central clearing not seen 6.Pityriasis Rosea → herald patch may resemble erythema migrans initially but no history of endemic exposure 7.Erythema Multiforme → target lesions → hands, feet, mucous membranes →hx of drug use or recent illness

Image

3 Hair

Presentation

ALOPECIA AREATA

Telogen effluvium

ANDROGENIC ALOPECIA

Hirsutism

Produces an area of smooth, discrete hair loss

hair that flows out

increasing scalp visibility in a typical distribution

male pattern overgrowth of androgen-dependent terminal hairs in female patients

m/c cause of diffuse scalp hair loss

causes: androgen excess due to familial, idiopathic, drug induced

reversible loss of mature, terminal hairs usually secondary to significant stress→ crash diet, emotional stress, medications, postpartum, post surgery, nutritional def/excess Distribution

usually the scalp but can occur on any hair bearing area

often occurs in women with endocrine disorders: polycystic ovarian disorder, adrenal hyperplasia, or pituitary disorder

women: more diffuse and rarely complete; increases at menopause men: M-shaped pattern in frontal hair-line

Lesions

alopecia in smooth circular discrete areas patches may coalesce into bizarre patterns Exclamation hairs (black dots of hair broken off close to scalp) are found at expanding edges

Sign

areas of regrowth: initially have fine hypopigmented (white) vellus hairs Severe emotional stress can be contributing factor nail involvement: fine pitting of the proximal nail plates

50% of hair is lost before becomes noticeable → clinician should not discount complaints of hair loss in someone who still has a full head

male-pattern: beard, chest, upper shoulders and groin

4 of hair Symptom Dx

presentation and presence of exclamation points hair root (plucked hair) is narrower and less pigmented than normal

1. Pull test: pull gently on 2-3 dozen hairs at same time more than 5 telogen (club) hairs is abnormal 2. Patients should count hair loss each day peak of disease: hundreds of hair lost daily - telogen hairs

family history in females is especially important examine scalp for other signs of hair disease ie follicular plugging women: menstrual pattern, acne, hirsutism

3. History of inciting event History

20% of individuals have a family Hx

--> diffuse hair loss that peaks around 3-4 months after initial event

Duration Pathophysiology

A stress triggers more hairs into telogen phase (resting)

there is a shortening of the anagen hair cycle with subsequent production of shorter, thinner hair shaft called follicular minimization causes often involve hormones

DDx

1. Tinea Capitis →Scaling 2.Nervous Hair Pulling (trichotillomania) →bizarre pattern of broken hairs of various lengths as

1.Anagen effluvium: →loss of growing (anagen) hair; because majority of hair is in this phase, acute loss involves 80-90% of hair →disease results from

1.Androgen excess in women: → history: fertility, menstrual, new onset of acne, signs of hirsutism 2.Telogen effluvium: →usually associated with

1. Hypertrichosis: →excessive hair growth in non-androgen dependent areas

5 compared with smooth hair loss of alopecia areata 3.Androgenetic alopecia →onset of hair loss is gradual and with a typical distribution pattern no exclamation point hairs found

chemotherapeutic agents 10-14 days after treatment

an acute event

2. Androgenetic alopecia: involves gradual, not acute hair loss from the frontal hairline or vertex

→history of precipitating event or drug

can be difficult to differentiate in women

3.Diffuse alopecia areata: →hair loss occurs on other body sites

]

→hair pull results +

→ biopsy may be necessary to distinguish

→more acute in onset and doesn’t follow a classic distribution Image Nails

Distribution

Paronychia an inflammation involving the lateral and posterior fingernail folds proximal and lateral nail folds

Lesions

acute: pustules

Presentation

Onychomycosis Fungal infection of the nail

Psoriasis vulgaris: nails 25% of psoriasis px’s

Feet m/c especially → great toe nail

fingernails and toenails especially with concomitant arthritis Piting Yellow oil spots Subungal hyperkaeratosis debris

secondary: erythema, edema, maceration, scale Sign

separation of nail plate distally and laterally from the nail bed nail dystrophy is caused by fungal involvement which accounts for the subungual hyperkeratotic scale and debris thickening & crumbling

Symptom

acute: pain & erythema of posterior or lateral nail folds followed by development of a superficial abscess chronic: abnormal seperation of proximal

6 Dx

nail fold from nail plate allows for colonization Clinical Findings

based on clinical findings of subungual hyperkeratotic debris, friable nail and coexisting tinea pedis KOH test -let sit 10 minutes positive in 50%

History

Duration DDx

predisposing factors: diabetes, mellitus, over manicuring, occupations that require individuals hands soaked in water

Predisposing factors: family history, underlying systemic disease ie psoriasis, immune suppression, poor circulation often disappears spontaneously

1.Herpetic whitlow: • exposure to HSV • lab test → tzanck smear 2. Subungal onychomycosis: • nail plate is friable and nail folds not predominantly involved 3. Pseudomonal nail infection: nail plate has a blue green tint

1. Psoriasis: • nail piting may coexist

2. Nail dystrophy secondary to eczema: No crumbling/debris may coexist

Image Drug Eruption Presentation

Distribution Lesions

Morbilliform Drug Eruption diffuse eruptions characterized by blanching, erythematous papules and macules in response to a drug

Fixed Drug Eruption Occurs in an asymmetric pattern at same sites with each challenge of drug

Phototoxic Drug Eruption occur as result of drug’s ability to enhance the skin’s reaction to ordinary light

extremities, glans penis, mucous membranes →macules, papules, bullae with secondary erythema, purplish hue, erosion and hyperpigmentation

eczematous; similar to contact dermatitis Confined to light exposed areas resemble sunburn that occurs within 24 hours after UV exposure

Photoallergic Drug Eruption May spread to areas not exposed to sun eczematous; similar to contact dermatitis

→ round and discrete and range from small, localized to large bullae

7 → erosions occur if bullae have erupted → heal as persistent, hyperpigmented macule Sign Symptom Dx

based on clinical appearance and history

characteristic skin lesions w/ hx of recurrent lesions at same site each time drug is taken

History Duration

DDx

these eruptions typically occur 7 –10 days after drug started and continue until 2 weeks after drug has been stopped 1. Viral Exantham →much shorter duration → no history of drug use 2. Pityrasis Rosea → herald patch → centripital scale

Image

1. Erythema multiforme: • Target lesions and lesions don’t occur in same location 2.Herpes simplex: • lesions occur as grouped blisters on an erythematous base and confined to one site • Tzanck smear positive

Occurs 24 hrs after sun exposure

48hrs after sun exposure

1. Allergic contact dermatitis: →involvement of shaded areas and history of exposure to contact allergens

1. Allergic contact dermatitis: →involvement of shaded areas and history of exposure to contact allergens

2. Lupus erythematous light eruption: →systemic findings often present

2. Lupus erythematous light eruption: →systemic findings often present