Chronic Cutaneous Lesion on the Left Lower Abdominal Wall

A 33-year-old previously healthy man presented with a 6-month history of a pruritic skin lesion on his left lower abdominal wall. Originally from Cape Town, South Africa, he immigrated to Canada 10 years ago. His travel history included a 1-month trip in Malawi 12 years prior, where he frequently swam in Lake Malawi. The skin lesion started with pruritic papules on his left lower abdomen that slowly progressed in size and developed a crust (Figure 1). He had multiple courses of antibiotics, valacyclovir, terbinafine, and over-the-counter steroid/antifungal creams, with no relief. A biopsy of the lesion is provided in Figure 1 below. Skin lesion on left lower abdominal wall. What is your diagnosis? Diagnosis: Ectopic cutaneous schistosomiasis. The biopsy demonstrated epidermal spongiosis with dermal granulomatous inflammation, eosinophils, and dermal fibrosis, associated with numerous ovoid structures in the dermis measuring approximately 120 × 50 μm (Figure 2). A rare terminal spine was observed on 1 structure (Figure 3), consistent with Schistosoma haematobium. Hematoxylin and eosin stain at ×4 power. Periodic acid-Schiff stain at ×20 power. The pathogen in question, located in the center of the picture, measures approximately 120 × 50 μm. Serology for schistosomiasis (enzyme-linked immunosorbent assay using antigens from S. haematobium and Schistosoma mansoni) was positive. Strongyloides, human immunodeficiency virus, hepatitis B, and hepatitis C serologies were negative. Stool ova and parasites examination (O&P) was negative. Unfortunately, urine O&P was not performed. An ultrasound of his abdomen was normal. The patient was treated with praziquantel 1800 mg (20 mg/kg) orally twice daily for 1 day with resolution of his skin lesion. Chronic schistosomiasis can cause significant morbidity among exposed individuals. Adult S. haematobium trematodes live in the pelvic venous plexus, depositing eggs into the urine. Manifestations of chronic S. haematobium infection are caused from the inflammatory response to egg deposition within tissues, with the most serious complication being squamous cell carcinoma of the bladder. Rarer manifestations of chronic S. haematobium infection can be observed within other organs including the lungs, skin, and central nervous system [1]. Most cases of ectopic cutaneous schistosomiasis occur predominately within the anogenital region, followed by the lower thorax and periumbilical areas [2–4]. The mechanism of ectopic migration of S. haematobium causing cutaneous involvement is not fully understood. Some authors hypothesize that migration of adult female worms from anastomosis connecting the pelvic venous plexus to spinal veins leads to the deposition of eggs in a zosteriform distribution [5–7]. Delayed presentation of cutaneous schistosomiasis from time of exposure has been observed in prior cases (up to 3 years), though our case is the longest described (12 years) [2, 8]. Ectopic cutaneous schistosomiasis is a rare manifestation of chronic schistosomiasis. Biopsy is required to confirm the diagnosis. Potential conflicts of interest. The authors: No potential conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

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