Spitz Nevus and Granuloma Annulare

Case 1:

This lesion has developed over the past 6 months on a 6-year-old's nose. It measures 3 mm and is reddish brown with a regular border.

Do you have to excise this lesion to determine what it is?

Case 1: This is a Spitz nevus--a benign pigmented lesion. Spitz nevi develop rapidly and commonly occur on the face. They are well circumscribed, smooth, and dome-shaped. They vary in size (from 2 to 20 mm in diameter, with an average of 8 mm) and color (from pink to tan to dark brown).

Spitz nevi were once thought to be a variant of malignant melanoma because of their histologic appearance. The clinical diagnosis is frequently difficult, given the rapid growth and pigmented nature of the lesion.

If the lesion is easily accessible, an excisional biopsy is recommended by many experts. However, if cosmetic issues are of concern, clinical guidelines become very important. A biopsy is essential if the lesion:

• Is larger-than-average size.

• Has an irregular border.

• Has asymmetric pigmentation.

• Is ulcerated.

The histologic appearance is distinct to an experienced dermatopathologist, whose opinion should be sought.

This lesion was excised from the patient's nose. Histologic findings confirmed the diagnosis of a Spitz nevus.

Case 2:

This 16-year-old boy presented to his pediatrician with a 3-month history of an expanding asymptomatic lesion on his wrist.

Do you recognize it?

Case 2: The very first case I saw in the dermatology clinic as a resident was a memorable one. I must have examined 4 potassium hydroxide preparations from a skin lesion just like this one before the attending let me off the hook and described granuloma annulare (GA). As a consultant, I see many cases of GA when the topical and systemic antifungal agents have failed.

The important clue I was missing as a resident was the lack of epidermal change in GA lesions. GA is composed of grouped dermal papules arranged in an annular or ringed configuration. The lesions begin as flesh-colored or red-brown papules without epidermal change, which spread to form rings that slowly expand with central clearing. The lesions show great variability in color. They may be flesh-colored with an erythematous border or a dull violaceous to gray-brown color centrally that pales at the palpable border to a flesh color.

GA has a number of unusual variants: subcutaneous, perforating, and disseminated. The most common variant in childhood is subcutaneous. Think of this diagnosis when subcutaneous nodules develop on the dorsal aspect of a patient's foot and interfere with the fit of his or her shoe.

More than 50% of patients with GA have single lesions. The dorsa of the hands and feet and the elbows and knees are the most common sites of involvement. The histologic appearance is characteristic, with collagen degeneration and pallisading granulomas. A biopsy is rarely required to make the diagnosis.

GA is a common disorder of school-aged children. Girls are affected twice as often as boys. Single lesions resolve within 2 years in half the affected children. However, there is a 40% recurrence rate (80% recur within 2 years).

A weak association between diabetes mellitus and single-lesion GA has been shown in adults. However, there is no conclusive evidence of a similar association in children.

The treatment of isolated lesions of GA is based on anecdotal reports and small case series. Topical corticosteroids of mid to high potency and intralesional corticosteroids are the agents of choice. These should be reserved for lesions of significant cosmetic concern as well as for lesions that are causing discomfort because of their size and/or location. These agents should be used for no more than 2 to 3 weeks (to avoid cutaneous atrophy). Unfortunately, there is very little evidence to suggest that these agents may be effective.