Publication

Abstract : A boy in his teens on long-term treatment with mycophenolate mofetil and steroids presented with a nodular swelling on the volar aspect of the right forearm. During the previous 2 months, he had experienced creeping eruptions of the right arm. The patient had never travelled outside India. Physical examination found a tender, well-defined 1 × 1-cm, mobile swelling in the subcutaneous plane with fixing of the skin. Ultrasound scan of the swelling revealed a 1.3 × 0.9 cm hyperechoic lesion suggestive of a live worm (Fig. 1, and see Supplementary material, video S1). Laboratory investigations showed a normal blood leucocyte count without eosinophilia. The excised cystic lesion on sectioning revealed a white thread-like, live worm in a coiled state (see Supplementary material, videos S2, S3). Scanning electron microscopy of the worm surface showed longitudinal ridges and transverse striations (Fig. 2A,B) ruling out Dirofilaria immitis. The worm was subjected to multiplex PCR, which identified it as Dirofilaria repens; however, sequencing of the cyclo-oxygenase type 1 gene identified it as Candidatus Dirofilaria hongkongensis.