Table 2.

Differential diagnosis of seborrheic dermatitis and dandruff.

Diagnosis		Diagnostic Clues
Psoriasis		Usually involves extensor, palmar, plantar, nails and extensor areas. Thick plaques sharply limited with silvery white scales. Positive family history. Arthritis present in 10% of patients. Uncommon in children.
Atopic Dermatitis		First appearance after 3 months of age, pruritus and restlessness are common. Frequently involves scalp, cheeks and extensor areas. Flexures involvement is more frequent in older ages. Family history of atopy such as eczema, allergic rhinitis and asthma. Self resolved by age 12.
Tinea Capitis		Commonly seen in children, frequently accompanied by hair loss patches with “black dots” (broken hair). Highly contagious. KOH examination of the hair shaft and fungal culture confirm the diagnosis. Household members of patient should be examined.
Rosacea		Usually targets the face. Papulopustules and telangiectasias on the malar, nose and perioral regions with slight desquamation. Recurrent edema and flushing.
Systemic Lupus Erythematous (SLE)		In acute stage, butterfly rash on face that spares the nose bridge or nasolabial folds. Photosensitivity is common. Skin lesions are generally associated with other clinical signs of SLE. Histology and serologic tests such as antinuclear autoantibodies confirm the diagnosis.
Others	Pemphigus Foliaceous	Erythema, scaling and crusting that first present on the scalp and face can expand to chest and back. Histology, direct immunofluorescence with anti-desmoglein antibodies confirm diagnosis.
	Pityriasis Rosea	Abrupt onset, appearance of herald patch and resolution within weeks.
	Secondary syphilis	Peripheral lymph-adenopathy, mucosal lesions and palmoplantar macula-papules. Serology tests such as VDRL/ RPR, FTA-ABS* confirm diagnosis.
	Diaper Dermatitis	Occurs on convex skin surfaces in contact with diaper, such as lower abdomen, genitalia, buttocks and upper thighs. Spares skin folds. Pustules are common.
	Langerhans cell histiocytosis	Multisystem disease. Brown to purplish papules prone to coalesce on the scalp, retro-auricular areas, axillae and inguinal folds. Possible lytic bone lesions, liver, spleen and lung involvement. Histology confirms diagnosis.

^*VDRL: Venereal Disease Research Laboratory; RPR: Rapid Plasma Regain; FTA-ABS: Fluorescent Treponemal Antibody-Absorption.