Danger lurks in the Mediterranean

Abstract

In February, 2009, a 52-year-old woman presented to us with a 2-month history of progressive swelling of the right cheek, which did not aff ect the eyelid or the lips. She had no previous medical history, recent trauma, surgery, medication (particularly no ACE inhibitors, which can cause facial swelling) and no history of skin tumours or autoimmune diseases. She was otherwise well, with no dyspnoea, dysphagia, xerostomia, pain, or itching. At another hospital, dental radiography and CT of the head showed right cheek soft tissue swelling. Histological examination of a biopsy sample of the buccal mucosa showed non-specifi c infl ammation. No exact diagnosis was established. The patient was prescribed amoxicillin with clavulanic acid for 3 weeks, followed by corticosteroids for 1 week, without clinical improvement. She was then admitted to our department for further investigations. On examination, she had distinct, soft swelling of her right cheek without infl ammation or scaling of the overlying skin. A subcutaneous mobile nodule was palpable enorally in the centre of the swelling. Saliva could be expressed from the salivary gland. Possible causes of unilateral cheek swelling (surgery, trauma, congenital disorders, drugs, dental disorders, salivary gland disorders, tumours, vasculitis, allergy, infections, and chronic infl ammatory disorders) were considered. ESR, blood count, aspartate and alanine aminotransferases, glomerular fi ltration rate, creatinine concentrations, and creatine kinase were normal. Serum tests for viruses, stool tests for parasites, and antinuclear antibodies were all negative. MRI showed diff use lymphoedema of the right cheek with a central distinct infl ammatory process. A deep incisional biopsy was done enorally at the centre of the right cheek swelling. Histology showed a chronic infl ammatory process with epitheloid granulomas. In the centre of one granuloma, we found an eosinophilic sickle-shaped fi gure, which was a section of a nematode identifi ed as Dirofi laria repens (fi gure). PCR confi rmed the diagnosis. Our patient was started on albendazole 400 mg twice daily for 3 weeks. The cheek swelling resolved within 4 weeks. On questioning about travel history, our patient recalled an insect bite 6 months previously, in Florence, Italy. At follow-up in June, 2010, the swelling had not recurred. D repens, a nematode of dogs and other domestic and wild carnivores, is endemic in southern and eastern Europe, south and central Asia, and Africa. It is transmitted by mosquitoes. People are only accidental hosts, and the parasites may be destroyed by the immune response. Pre-adult worms migrate subcutaneously and cause non-specifi c infl ammatory symptoms such as subcutaneous oedema due to obstructed lymph vessels. Subcutaneous nodules are a result of foreign-body granulomas around the worm. Infection is most common in the upper body, especially the face. The epidemiology of human dirofi lariasis is related to the prevalence of infected dogs, the presence of mosquitoes, suitable climate, humidity, and human activities that lead to exposure. The incidence in Europe has grown substantially in the past 50 years. Diagnosis is made on morphological examination of the worm, after surgical excision. Eosinophilia or raised IgE concentrations are rare. Ultrasonography and MRI can diff erentiate subcutaneous dirofi larial lesions from those of other aetiologies. Treatment of cutaneous dirofi lariasis consists of total excision of the nodule. The goal of anthelmintic therapy (ivermectin or albendazole) is to eradicate the infection if secondary lesions or incomplete excision are suspected. With global warming, fi larial infection might spread into previously infection-free areas. Dirofi lariasis must be considered in particular in cases with chronic progressive swelling.