Anaphylaxis after surgical excision of subcutaneous infection with parasiticDirofilaria

• Published in: Hong Kong medical journal = Xianggang yi xue za zhi 2021-08, Vol.27 (4), p.297
• Main Authors: Brian WC Luk, Cheung, C N, Chan, Y F
• Format: Article
• Language: chi ; eng
• Subjects: Allergens; Allergies; Anaphylaxis; Asymptomatic; Blood tests; Cysts; Cytochrome; Dissection; Erythema; Histamine; Hypotension; Infections; Inflammation; Parasites; Skin; Zoonoses
• ISSN: 1024-2708; 2226-8707
• DOI: 10.12809/hkmj208675

Clinical photograph of a 21-year-old patient with dirofilariasis showing the development of skin swelling on theleft proximal volar forearm after the onset of erythema Microscopy of the nodule revealed a piece of fibro-fatty tissue with mixed inflammatory cell infiltrate and dense eosinophilic infiltrate (Fig 2a), and a 0.72 mm [x] 0.29 mm fragment of degenerated parasite rimmed by foamy histiocytes (Fig 2b). The surgical margin measured from the edge of the surrounding granulomatous inflammation to the closest edge of the excised specimen was 0.82 mm. Further molecular study by polymerase chain reaction and DNA sequencing based on Filarioidea cytochrome oxidase subunit I (cox1) and specific 12S ribosomal RNA (12S rRNA) gene revealed the parasite to beDirofilaria hongkongensis.1 Figure 2. Histopathological results from the same patient showing (a) degenerated parasite with ghost outline of themuscular layer and tubular structure, measuring 0.72 mm [x]0.29 mm (haematoxylin and eosin, [x]100) and (b) mixedinflammatory cell infiltrate with dense eosinophilic infiltrate(haematoxylin and eosin, [x]400) The patient remained symptom-free and differential WBC and C-reactive protein were normal at 6 months after surgery. Dirofilaria hongkongensis was first proposed as a distinct species in 2012, following three cases of human infection.2 In stray dogs in Hong Kong, the seroprevalence of D hongkongensis is 3%,2 and that ofD immitis is 10%.6 Molecular study in nucleotide sequencing of cytochrome oxidase subunit 1 (cox1) gene and the 12S ribosomal RNA (12S rRNA) gene is useful in the identification of Dirofilaria species, taking reference from GenBank data.