Bullous cutaneous larva migrans: case series and review of atypical clinical presentations.

Hookworm-related cutaneous larva migrans (HRCLM) is caused by the penetration and migration in the epidermis of larvae of Ancylostoma braziliense and Ancylostoma caninum. It is characterized by slightly raised and erythematous tracks, located especially on the feet. These tracks may be single or multiple, serpiginous or linear, ramified and intertwined, accompanied by pruritus. Atypical clinical presentations of HRCLM are currently more frequent than in the past. We present six patients with bullous HRCLM and discuss the possible pathogenetic factors. Furthermore, we present a review of atypical clinical presentations of HRCLM. From 1998 to 2013 we observed approximately 180 patients with HRCLM. In all patients race, nationality, sex, age, country of infestation, location of the disease, clinical picture, laboratory and instrumental examinations and therapy were collected. In six patients (4 males and 2 females), we made a diagnosis, based on the history and clinical picture, of bullous HRCLM. The infestation was characterized by single or multiple blisters, round or oval in shape, of different size, with a clear serous fluid. Some tracks were also visible. All patients complained of pruritus. General physical examination and laboratory and instrumental examinations were normal or negative. Cytological examinations of the blisters showed the presence of lymphocytes and neutrophils, with numerous eosinophils. All patients were successfully treated with oral albendazole. Blisters appear because of the release by the larvae of lytic enzymes (metalloproteases and hyaluronidases). Furthermore, blisters might be the final clinical result of a delayed hypersensitivity reaction due to the release by larvae of unknown antigens. Finally, only in some patients, bullous HRCLM might represent an acute irritant/allergic contact dermatitis caused by topical drugs applied on the lesions. This hypothesis has been excluded in our patients because no topical treatment was made before our observation.