By Gary M. White, MD
Erosive Pustular Dermatosis of the Scalp (EPDS). Crusted plaques, often with green pus underlying are typical of EPDS. It most commonly affects the bald areas of elderly men. Rarely, kerion can mimic this condition [Cutis 2013;91;73].
Bacterial Folliculitis of the crown in a young male is not uncommon.
Cutis Verticis Gyrata
The most common cause of scalp itch is seborrheic dermatitis (SD). Any patient with scalp itch should have a careful examination looking for the redness and scale of SD. Examination behind the ear and ear canal may also show scale, etc., helping to confirm the diagnosis. Again, the vast majority of patients who present with itching of the scalp have something along the spectrum of dandruff/seborrheic dermatitis/psoriasis.
If redness and scale are not found, look for pustules anywhere (acne necrotica, dissecting cellulitis, etc.) or hyperkeratotic lesions in patients, usually men, with thinning hair (sun damage and actinic keratosis). Finally, inquire about any recent hair loss. In addition, the patient should be asked if s/he has noticed any recent hair loss as pruritus is often associated with hair loss of a variety of causes. If there is no hair loss and no primary lesion is found, then a potent topical steroid should be prescribed, e.g., clobetasol solution. If that does not help, then the diagnosis of scalp dysesthesia syndrome may be entertained. In that, diffuse itching, burning, numbness or tingling of the scalp without any primary lesion is seen.
Metastatic Disease. Here lung cancer.
Epidermal Inclusion Cyst
Spreading Pigmented Actinic Keratosis
Melanoma. If there is plenty of hair, melanoma is uncommon in the scalp. Once the hair thins and UV does its damage, melanoma may occur. See also melanoma scalp.
Dissecting Cellulitis of the Scalp
Eosinophilic Pustular Folliculitis. This occurs in infants.
Erosive Pustular Dermatosis of the Scalp (see above).
Seborrheic Dermatitis. The difference between seborrheic dermatitis (SD) and psoriasis is a matter of degree. SD is milder than psoriasis. Lesions on the body imply psoriasis. Still, overlap occurs and some patients fall in the middle.
Allergic Contact Dermatitis. Rarely, patients may be allergic to a component of their shampoo or to black hair dye, etc.
Angiosarcoma of the Head and Neck
Neonatal Lupus Erythematosus
Pityriasis Amiantacea. Most common in children.
Langerhans Cell Histiocytosis
Several features should make the clinician consider that a scalp nodule may be more than just a pilar cyst or epidermal inclusion cyst. Those lesions arising in the midline or along suture lines, arising after trauma or cranial surgery, congenital lesions, pulsatile, nonmobile, and those with bruits deserve preoperative radiologic evaluation. Surgery on hemangiomas or temporal artery aneurysms which are thought to be cysts can lead to significant operative complications [JAAD 1993;29;260].
Heterotopic Brain Tissue
Hair Collar Sign. Courtesy O. Dale Collins, MD
Scalp Electrode Laceration
AEC Syndrome. Denuded skin at birth and chronic scalp erosions, complicated by infection are characteristic of this syndrome.
Nevus Sebaceous (see above).
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