Bilharziasis cutanea tarda : a rare manifestation of Schistosomiasis

INTRODUCTION & OBJECTIVES: Bilharziasis (or Schistosomiasis) is a chronic trematode infection endemic in 74 tropical developing countries, and more than 207 million people are infected worldwide. Cutaneous manifestation can occur few hours after skin penetration by cercariae, the swimmer’s itch, approximately 4-8 weeks after initial exposure with urticaria, fever and eosinophilia, and in the late stage of infestation, the so called bilharziasis cutanea tarda. We report a very rare case of late cutaneous manifestation of bilharziasis in a 42-year-old woman with gluteal involvement without visceral symptoms RESULTS: A 42-year-old Brazilian woman presented to our department with a three months history of mildly pruritic papular eruption on the gluteal region resistant to topical steroid therapy. Physical examination showed an erythematous violaceus plaque in the right intergluteal fold and a firm, erythematous brownish papules, some in a linear pattern, in her left gluteus and thigh. There were no systemic symptoms. Histopathologic examination of a skin biopsy taken from an intergluteal plaque revealed several ova of Schistosoma mansoni (S.mansoni) with characteristic lateral specula, distributed in reticular and papillary dermis. These ova were surrounded by a granulomatous cell infiltrate. The patient reported having swum in a lake of Minas Gerais state in Brazil a five years before the outbreak of skin lesions. A diagnosis of bilharziasis cutanea tarda caused by S. mansoni of the gluteal region was performed. Serologic examination for Schistosoma was positive, parasitological examination of urine and stool was negative, and abdominal ultrasound examination and thorax radiography were normal. The woman was treated with praziquantel 20 mg/kg in two doses 4 hours apart. Two months after therapy the patient showed resolution of cutaneous lesions CONCLUSIONS: S. mansoni is a parasite of the inferior mesenteric veins of the colon and produce ova with a prominent lateral spine. It is the only trematode causing schistosomiasis in Brazil. Ectopic schistosomiasis presentation occurs when the parasite eggs or adult form are located far from their normal site. When ectopic schistosomiasis involves the skin is called bilharziasis cutanea tarda. The ectopic deposition of ova of S.mansoni within dermis is extremely rare even in endemic countries. In literature less than 40 cases caused by S. mansoni are reported in Brazil. Beside the rarity of this entity, it is important to underline that bilharziasis cutanea tarda has no specific clinical appearance. Diagnosis of this skin manifestation is difficult and represents a clinical challenge for dermatology, especially in non endemic regions.