JPC SYSTEMIC PATHOLOGY
INTEGUMENTARY SYSTEM
November 2025
I-P11
Signalment (JPC# 1685305): An age and breed unspecified chicken
HISTORY: Numerous yellowish nodules up to several millimeters in diameter were noted at slaughter.
HISTOPATHOLOGICAL DESCRIPTION: Feathered skin: Within the subcutis are many variably sized, oval to elongate, cavitations (up to 500 µm) surrounded by dense collagen that contain multiple tangential and cross sections of arthropods. The arthropods are up to 400 µm in diameter and are characterized by a chitinous exoskeleton with spines, jointed appendages, a hemocoel, striated muscle, gastrointestinal organs, and male or female reproductive tracts. There is moderate to marked postmortem degeneration due to scalding and autolysis.
The other tissue sections on this slide are not related to Laminosioptes cysticola.
MORPHOLOGIC DIAGNOSIS: Feathered skin, subcutis: Cysts, multifocal, with multiple arthropod mites, chicken, avian.
ETIOLOGIC DIAGNOSIS: Subcutaneous acariasis
CAUSE: Laminosioptes cysticola
CONDITION: Laminosioptiasis
CONDITION SYNONYMS: Subcutaneous mite
GENERAL DISCUSSION:
- Infection is usually in older, emaciated poultry kept in unsanitary conditions
- Lesions cause carcass condemnation
PATHOGENESIS:
- All stages develop under the skin or in deep tissues of the host
TYPICAL CLINICAL FINDINGS:
- Typically no clinical disease, but heavy burdens may cause retarded growth, reduced egg production, lowered vitality, damaged plumage and even death
TYPICAL GROSS FINDINGS:
- Round to oval, yellowish, caseous and calcareous nodules in subcutaneous tissues, muscle, abdominal viscera, and lungs
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Mites are found in subcutis, peripheral nerves, heart, lungs, air sacs, abdominal viscera, muscle, and reproductive tracts
- There is little or no inflammation associated with intact mites, but degenerate acarids and exoskeletal fragments elicit mild to moderate granulomatous reaction with mineralization
DIFFERENTIAL DIAGNOSIS:
- Tuberculosis: Subcutaneous nodules can be mistaken for tuberculoid lesions (distinguished by the presence of acid‑fast bacilli)
- Cytodites nudus (P-P19): Poultry air‑sac mite; it occurs in respiratory passages, air sacs, and other internal organs of domestic fowl and pheasants
COMPARATIVE PATHOLOGY:
- Rarely seen in pet (non-poultry) birds
OTHER SPECIES OF MITES OF IMPORTANCE TO POULTRY:
- Red mite (Dermanyssus gallinae): Feed on poultry (blood) at night, but hide in environment during day; heavy infestations can result in anemia and death; can transmit Pasturella multocida (Fowl Cholera) and Brachyspira (Avian Spirochetosis); also rarely infect horses, cattle, dogs, and cats
- Northern fowl mite (Ornithonyssus sylviarum): most significant poultry ectoparasite; bloodsuckers that stay on the bird, particularly around the vent; cause dermatitis with scabbing and cracked skin; transmit Fowl Pox, Newcastle disease (paramyxovirus), ornithosis (Chlamydia psittaci), and certain encephalitides; also rarely infect horses
- Depluming mite (Knemidokoptes gallinae): Chickens, pheasants and pigeons; burrow into the basal shaft of feathers, causing pruritus and loss of feathers
- Scaley leg mite (Knemidokoptes mutans [I-P12]): live within unfeathered skin on the legs, feet, and occasionally the comb, wattles, and beak; causes hyperkeratosis with powdery, exfoliating crusts; poultry and pet birds
REFERENCES:
- Fitz-Coy SH. Parasitic diseases. In: Boulianne M, et al, eds. Avian Disease Manual. 8th ed., Jacksonville, FL: American Association of Avian Pathologists, Inc.; 2019:127-128.
- Schmidt RE, Reavill DR, Phalen DN. Pathology of Pet and Aviary Birds. 2nd ed., Ames, IA: John Wiley and Sons, Inc.; 2015:204, 239.
