Zoonoses Presenting as Head and Neck Swellings

A two-year-old boy presented with a painless, gradually enlarging swelling on his left cheek.

His swelling was first noticed nearly 10 months back. Initially grape-sized, it grew to the size of a cherry without associated fever, oral pain, or halitosis. There were no systemic abnormalities. Detailed history revealed that the child had been exposed to stray dogs. Antibiotics prescribed for initial skin redness were ineffective. 

Physical examination revealed a smooth, non-tender, cystic swelling (3 x 2 cm) palpable through the buccal mucosa. 

Blood tests indicated eosinophilia (hemoglobin 11.2 g/dL, leukocyte count 10,200/µL, eosinophil count 800/µL, platelet count 204,000/µL). Ultrasonography showed a cystic lesion with internal serpiginous lines, suggestive of filariasis. 

Differential diagnoses included cyst, abscess, lipoma, granuloma, mucocele, and tumors. 

Surgical excision confirmed Dirofilaria worms. Histopathology revealed fibrofatty tissue with eosinophilic inflammation. No further treatment was required post-excision due to the absence of systemic symptoms.

Zoonotic diseases can present with various symptoms, including subcutaneous swellings.Dirofilariasis, also known as "dog heartworm," is caused by filarial worms transmitted to humans through mosquito bites from infected animals. It manifests as subcutaneous, ocular, or pulmonary dirofilariasis. 

In India, D. repens commonly causes subcutaneous swellings. Risk factors include high mosquito density, warm climate, and close contact with dogs. Surgical excision is both diagnostic and therapeutic. Anti-helminthics are unnecessary as human Dirofilaria is reproductively inactive and usually localized.

Children with unexplained fever and subcutaneous swelling should be evaluated for zoonotic diseases using eosinophilia, serology, and ultrasonography. Controlling stray animals and mosquito populations is crucial for prevention.

Source:Eapen EK, Maya R, Sekhar SR, et al. Indian Pediatrics. 2024 Apr 5:S097475591600627-.