Significance of Gram's stain smear, potassium hydroxide mount, culture, and microscopic pathology in the diagnosis of acrodermatitis continua of Hallopeau.

A 21-year-old housewife presented to the authors' clinic in 2009 with recurrent papulovesicular and pustular eruptions on the index an ring fingers of the left hand accompanied by throbbing pain that had been active for the past 10 years. The condition did not respond to topical and/or systemic treatment. There was neither a personal/family history of psoriasis nor any other systemic disease. The sk surface of the patient's left hand was marked by the presence of multiple pustules located over an erythematous background, affecting th ring and adjoining middle fingers, with crusting prominent in places along the tips (Figure 1). Gram-stained smears prepared from th purulent specimen revealed Gram-positive cocci in clusters. Potassium hydroxide (KOH) examination of the pustules did not show a fungal elements. In vitro culture of the same specimen yielded growth of Staphylococcus aureus, which was found to be sensitive to almo all conventional antibiotics on aerobic culture. Sections prepared from the skin of the tip of the patient's finger showed marked epithelial hyperplasia with uniform elongation of rete ridges and supra-papillary thinning of the epidermis. There was hyperkeratosis with foci of mounds of parakeratosis. Spongiosis with neutrophilic infiltration and microabscess formation were prominent. The dermis showed perivascular lymphohistiocytic infiltrate (Figure 2A and 2B). No organism was identified on special stains. Results from hemography and liver and renal function tests were within normal limits. The diagnosis of acrodermatitis continua of Hallopeau (ACH) was made, in keeping with the findings. The patient received ceftriaxone 1.0 g and tazobactam 125 mg by slow intravenous infusion for 3 consecutive days, following which there was complete regression of the lesions. After cessation of therapy, there was complete recurrence.