September 2017

P-M04 (NP)


Slide A

Signalment (AFIP 2086741):  11-year-old male Boston terrier

HISTORY:  The dog has a history of tricuspid and mitral valve insufficiency.


Lung:  Affecting up to 60% of the distal margins of examined lung sections, alveoli are filled and expanded by accumulations of an amorphous, homogeneous, amphophilic, anisotropic, hyaline material up to 200um in diameter that are often surrounded by granulomatous inflammation characterized by macrophages that occasionally contain phagocitized material, rare multinucleate giant cell macrophages, and lamellar bands of reactive fibroblasts and collagen (fibrosis), admixed with low numbers of plasma cells and lymphocytes.  Multifocally there is moderate type II pneumocyte hyperplasia.  The perivascular and peribronchiolar adventitia is expanded by clear space with ectatic lymphatics (edema) and low numbers of lymphocytes and plasma cells.  Multifocally there are small clusters of macrophages containing brown to black granular pigment (anthracosilicosis).

MORPHOLOGIC DIAGNOSIS:  Lung:  Pneumonia, granulomatous, multifocal, moderate, with abundant intra- and extracellular, homogenous, amphophilic, hyaline material, Boston terrier, canine.

CONDITION:  Pulmonary hyalinosis

Slide B

Signalment (AFIP 2695446):  18-week-old C57BL/6L viable moth-eaten male mouse (Mus musculus)

HISTORY:  This mouse was from a mutant colony maintained at the Jackson laboratory.


Lung:  Multifocally affecting 60% of this section, alveoli are filled and expanded by abundant acicular to rhomboid-shaped, intensely eosinophilic crystals which are often packed within macrophages and rare multinucleate giant cell macrophages.  Multifocally, bronchiolar epithelium is expanded by similar eosinophilic crystalline material.  In more severely affected areas, alveolar septa are thickened by moderate type II pneumocyte hyperplasia and a mild increase in fibrous connective tissue (fibrosis).  Multifocally, macrophages also contain a light brown granular to globular pigment (hemosiderin). The perivascular and peribronchiolar adventitia is expanded by clear space with ectatic lymphatics (edema) and low numbers of lymphocytes and plasma cells.

MORPHOLOGIC DIAGNOSIS:  Lung: Alveolitis, granulomatous, multifocal, moderate, with abundant intrahistiocytic eosinophilic crystalline material and hemosiderosis, C57BL/6L viable moth-eaten mouse (Mus musculus), rodent.

CONDITION:  Acidophilic macrophage pneumonia (eosinophilic crystalline pneumonia)

CAUSE:  Unknown


Pulmonary hyalinosis

Acidophilic Macrophage Pneumonia (AMP, eosinophilic crystalline pneumonia)

PATHOGENESIS:  Unknown, suspected response to chronic lung injury (e.g. pneumoconiosis or experimental radiation pneumonitis)

TYPICAL CLINICAL FINDINGS:  None; often incidental finding



Pulmonary hyalinosis

Acidophilic Macrophage Pneumonia




Epithelial Hyalinosis


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  3. Caswell JL, Williams KJ. Respiratory system. In: Maxie ME, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. 6th ed. Vol 2. Philadelphia, PA: Elsevier; 2016:517.
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  5. Hoenerhoff MJ, Starost MF, Ward JM. Eosinophilic crystalline pneumonia as a major cause of death in 129S4/SvJae mice. Vet Pathol. 2006:682-688.
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  7. Sokol SA, Agnew DW, Lewis AD, et al. Pulmonary hyalinosis in captive sugar gliders (Petaurus breviceps). J Vet Diagn Invest. 2017 Apr 1:1040638717703683. [Epub ahead of print]
  8. Ward JM, Yoon M, Anver MR, et al. Hyalinosis and Ym1/Ym2 gene expression in the stomach and respiratory tract of 129S4/SvJae and wild-type and CYP1A2-null B6, 129 mice. Am J Pathol. 2001 Jan;158(1):323-32.

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