Microscopically, the primary differential diagnosis is EED, insect bite reaction, cutaneous lymphoma, or leukocytoclastic vasculitis. The exact pathogenesis is unclear, but some consider it a variant of leukocytoclastic vasculitis. Immunoglobulins, fibrin, and complement can be found at the dermal-epidermal junction and around blood vessels on direct immunofluorescence.28-30
GF usually lacks systemic symptoms or laboratory findings other than rare peripheral eosinophilia.31 Immunohistochemical analysis revealed the majority of lymphocytes to be helper T-cell lymphocytes. The cells stained strongly with antibodies against IL-2 receptor and with antibodies to lymphocyte functional antigen-1 α. Overlying keratinocytes did not stain with intracellular adhesion molecule-1 or HLA-DR, which may account for the presence of the grenz zone in GF. These findings suggest that a γ–interferon-mediated process may play some role in the pathogenesis of this disorder.32
GF is known to be resistant to therapy. Numerous physical modalities and medical therapeutics have been tried. Laser therapy, including the CO2,33 argon,34 pulsed dye, and long-pulsed tunable dye lasers,35-38 all have been attempted with varying success. A study showed that lesions treated with a CO2 laser and dermabrasion had a more even texture compared with lesions treated with electrosurgery alone. Healing times were similar between lesions treated with electrosurgery and CO2 laser; however, lesions treated with dermabrasion healed more quickly.39 Studies of patients treated with an argon laser resulted in total resolution of plaques of GF but had a remaining white collagenous scar.34
A case report by Elston37 showed complete resolution of 3 lesions of GF when treated with a pulsed dye laser after the patient failed topical corticosteroids and oral dapsone. A case report by Ammirati et al35 of a patient treated with the 585-nm pulsed dye laser showed clinical eradication of the lesion at 6-year follow-up. Another report by Welsh et al36 showed good results when GF was treated with the pulsed dye laser. Recently, the long-pulsed tunable dye laser was used successfully with no scarring.38 Other modalities that have been used include surgical excision,7,10 dermabrasion, superficial ionizing radiation,6,10 topical psoralen plus UV light,40 cryosurgery,41 intralesional corticosteroids,42 combined cryosurgery and intralesional steroid injection,43 and electrodesiccation.10,39
Medical treatment has included intralesional gold, colchicine, isoniazid, corticosteroids, potassium arsenite, testosterone, antimalarials, dapsone, and clofazimine.9,10,25,27,34,39,44-46 Most medical therapies have shown varying success. No controlled trials are available because of the rarity of the condition.
In our review, most patients were treated with topical and intralesional steroids with varying results that ranged from mild improvement to complete resolution. Because there is a lack of scarring with steroid therapy, we recommend this as a good first-line therapy. Although none of the patients were treated with pulsed dye laser therapy, review of the literature demonstrates favorable results with this treatment modality. Pulsed dye laser should be considered as an alternative therapy.