Condition

Clinical Presentation

Differentiating Factors

Scabies

Contagious skin infection caused by mites. Pruritic rash that may worsen at night.

Tiny papules can arrange in a line as the mites burrow under the skin.

Common locations are in-between fingers and toes, under jewelry, and in skin folds.

Seborrheic Dermatitis

An inflammatory skin disorder that is chronic and relapsing with preferential development in areas with sebaceous glands.

Poorly defined erythematous patches with scaling.

Scalp and face (nasolabial folds, eyebrows, ears, postauricular areas, and beard areas) are most often affected.

More common and severe in patients with HIV or neurologic

disorders.

Contact Dermatitis (Irritant/Allergic)

Caused by contact with chemicals which patients are exposed to.

Typical distribution on hands, feet, face, or eyelids.

Can present unilaterally.

Patch testing is utilized to diagnose by replicating the allergic reaction to the offending chemical.

Clinical history of eruption following exposure.

Ichthyoses

Phenotypic results of gene mutations leading to skin barrier failure.

Extensive and chronic scaling of the skin that is often

combined with xerosis, fissures, erythema, and sometimes pruritus.

Genetically inherited disorder.

Multiple variations.

Psoriasis

Clearly demarcated erythematous plaques combined with silvery scales.

Extensor and scalp surface involvement.

Can involve nail changes (pitting, onycholysis, and subungual hyperkeratosis)

Cutaneous T-cell Lymphoma (Mycosis Fungoides)

Fixed asymptomatic patches in sun-protected areas.

Failure of resolution with topical steroids.

Photosensitivity Dermatitis

Clinically eczematous morphology, but occurring primarily in sun-exposed skin.

Distribution on sun-exposed skin: face, neck, upper chest, forearms, hands.

Immunodeficiency Disorders (e.g. Hyper-IgE syndrome, SCID)

Eczematous dermatitis is a common finding in immunodeficiency disorders. These skin findings may be the presenting clinical manifestation to a dermatologist

Recognition of additional immunodeficiency features can help facilitate diagnosis.

Erythroderma of Other Causes (*)

Widespread erythroderma which may be due to psoriasis, AD, CTCL, seborrhea.

Biopsy may be helpful to distinguish between diseases in the differential.