Photoinduced Classic Sweet Syndrome Presenting as Hemorrhagic Bullae

^{Figure 3. Polymorphonuclear neutrophilic infiltrate with multilobulated nucleus without leukocytoclasia (H&E, original magnification ×100).}

Bullous-type SS has been reported, but all the known cases were secondary to malignancy or were drug induced^8,10; they did not present in a classic or idiopathic variant. Our case is unique in that it is a report of the classic SS variant with lesions including bullae over photoexposed areas, possibly indicating a causal association of sun exposure and the development of SS.

^{Figure 4. Intravenous dexamethasone resulted in improvement within 4 to 5 days of treatment.}

The diagnostic histopathologic features of SS include a dense, predominantly neutrophilic infiltrate located in the superficial dermis as well as prominent papillary dermal edema, which occasionally may lead to subepidermal vesiculation.^11,12 The epidermis often is normal but spongiosis may be present, and rarely neutrophils may extend into the epidermis to form subcorneal pustules.¹³ Severe edema in the papillary dermis may cause subepidermal blistering and bullous lesions.¹⁰ Systemic steroids are the therapeutic mainstay in SS. Other treatment options include methylprednisolone, potassium iodide, colchicine, indomethacin, cyclosporine, and dapsone.