Suspected Laminosioptes cysticola (fowl cyst mite) lesions in backyard chickens in southern England

Postmortem examination of poultry from several backyard flocks in the south of England revealed five chickens (Gallus gallus) from one backyard flock with lesions compatible with the fowl cyst mite (Laminosioptes cysticola). All affected birds were mature hens and had subcutaneous and fascial, randomly scattered, 1–5 mm, calcareous nodules. Histological findings included a thin fibrous capsule, embedding glassy, pale basophilic acellular material that stained positive with von Kossa histochemistry consistent with mineralization. There were also some granulomatous lesions, detected in two of five birds, that were biconvex and made of an accumulation of amorphous eosinophilic material, collagen-like fibrillary material and fibroblasts, embedding some yellow to brown, refractile flakes and fragments of foreign bodies (suspected acarid exoskeletal remnants). Fresh and formalin-fixed tissues were examined by PCR for mite DNA with no positive results. Laminosioptes mites may be present in British backyard poultry.