Abstract:

A 43-year-old female patient from Yushu, Qinghai, presented to the respiratory department of the Affiliated Hospital of Qinghai University due to “intermittent chest and back pain discomfort for more than 4 months” In September 2022. Physical examination upon admission revealed subcutaneous nodules approximately 1 cm × 0.5 cm in size, palpable on the anterior chest, above the right upper limb elbow joint, and on the left lower limb knee joint, with significant tenderness. Blood test showed an eosinophil count of 15.58 × 10⁹/L, an eosinophil percentage of 67.4% and an erythrocyte sedimentation rate of 17.00 mm/h. Bone marrow examination results indicated active hematopoietic tissue proliferation in the bone marrow, with a significant increase in eosinophils, accounting for approximately 62% of nucleated cells. Skin biopsy pathology revealed focal lymphocyte, plasma cell, and eosinophil infiltration around blood vessels and between adipose lobules. Treatment with oral prednisone acetate tablets (60 mg/d) for one month did not alleviate the pain in the subcutaneous nodules. In November 2022, a total of 5 fly larvae emerged successively from subcutaneous sites on the patient’s left ear, right lower limb, left upper limb, neck and anterior chest. Morphological identification confirmed them as Hypoderma bovis larvae. The patient is a herdsman residing in a plateau pastoral area for a long time, with a history of sleeping on grass and drying clothes on the grass during summer. Based on the epidemiological investigation, clinical manifestations, and relevant examination results, the final diagnosis was secondary eosinophilia due to cutaneous myiasis caused by H. bovis larvae. After confirmation of the diagnosis, the patient was treated with oral albendazole (0.4 g/d) and loratadine tablets (10 mg/d) for 13 days. A follow-up blood test showed that the eosinophil count returned to normal, and the patient’s symptoms improved. During a one-year telephone follow-up, the patient did not report any recurrence of skin pain or other discomfort.

Key words: Skin fly maggot disease, Eosinophilia, Subcutaneous migratory nodule