Slides 5 and 6: Right Shoulder and Left Epaxial Skin respectively

Sections are similar to that described in Slide 4.  In addition, left Epaxial skin reveals sections of vacuolated and degenerated erector pili muscle in the adnexae.  The apnniculus has a deep thin band of fibrous connective tissue which multifocally to extensively has small to moderately has small to moderate amounts of deeply basophilic granular material (mineralization) (calcinosis cutis).

Slide 7: Brain: Basal Ganglia

Within normal limits (WNL)

Slides 8-10: Brain

Focally, in and around the pituitary area (extensively within the hypothalamus) is an unencapsulated, well-demaroated invasive neoplasm composed of polyhedral to pleomorphic cells arranged as pseudorosettes, perivascular pseudorosettes, irregular disorganized cords and few variably sized tubules within a fine well-vascularized connective tissue stroma.  The cells have variably distinct borders, moderate to large amounts of pale finely granular eosinophilic cytoplasm, and oval nuclei with finely to coarsely stripped chromatin and occasionally 1-2 nucleoii.  Cells in pseudorosettes tend to have basally located nuclei.  In deep (dorsal) areas, the cell poluation tends to be more disorganized and anaplastic, with severe anisocytosis and anisokaryosis (especially evident in Slide 8) and occasional karyomegalic cells with pleomorphic nuclei containing coarsely-stippled chromatin and 1-3 prominent nucleoi.  Mitoses are rare (0-1 PHF- 400x).  Occasionally, deeply basophilic fragmented foci of mineralization are noted.  The mass Multifocally has abundant central necrosis replete with eosinophili cellular and karyorrhectic debris, and acicular clefts, occasionally bordered by few macrophages with contain yellow granular pigment (ceroid).  Surrounding parenchyma is markedly compressed.

Slides 9 and 10:  Midbrain and cerebellum

WNL

HISTOPATH DX

1. Pituitary (chromophobe) adenocarcinoma
2. Bilateral adrenocortical hyperplasia, diffuse, chronic, marked, adrenal glands
3. Endocrine dermatophathy, diffuse, chronic, severe, skin
4. Steroid hepatopathy, diffuse, chronic, marked, liver
5. Multiple renal cysts; mild multifocal chronic interstitial nephritis

HISTO COMMENT

Histopathologic findings confirm a pituitary adenocarcinoma.  With prominent secondary changes of adrenocortical hyperplasia, endocrine dermatopathy (including calcinosis cutis), and steroid hepatopathy, this tumor was presumably a functioning corticotropic neoplasm and the cause of the hyperadrenocorticism (Cushing’s disease) in this dog.  Neurologic signs were due to compression and replacement of structures in the brain by the mass.