Test 3: lab 6 skin Flashcards
Diagnosis:
If the tumor was functional, predict which hormone would be produced, and what clinical features would you expect?
Pituitary adenoma/carcinoma (likely carcinoma due to size and compression/invasion of overlying parenchyma)
Functional pituitary tumors in dogs typically produce ACTH. Associated clinical signs include panting, pendulous abdomen, pol yuria and polydipsia, polyphagia, palpably enlarged liver (steroid hepatopathy), muscle atrophy, alopecia, thin skin, and scaling.
What change would you see in the target organ (adrenal glands) when dog has pituitary tumor?
Bilateral adrenocortical hyperplasia
What specific skin lesion may be present with function pituitary tumor?
Calcinosis cutis
If functional pituitary tumor, what liver enzyme is likely elevated? What would you find if you measured serum cortisol and ACTH?
Increased ALP, cortisol, and ACTH
What clinical signs can be attributed to compression and invasion of the surrounding tissue?
If the tumor was nonfunctional, the dog may have still presented with clinical signs due to the tumor’s compression and invasion into surrounding tissues. These signs could include blindness (compression of optic chiasm or nerves), behavioral changes, or seizures. Furthermore, compression of the hypothalamus and pituitary stalk can lead to decreased ADH and subsequent diabetes insipidus.
Match each pair of adrenal glands with the appropriate clinical history below:
normal
Dog with polyuria and polydipsia, enlarged liver, pendulous abdomen, and increased panting. Bloodwork shows decreased ACTH. The dog is also being treated long-term with high doses of corticosteroids for pemphigus foliaceus.
Dog with polyuria and polydipsia, enlarged liver, pendulous abdomen, and increased panting. Bloodwork shows decreased ACTH.
Dog with polyuria and polydipsia, enlarged liver, pendulous abdomen, and increased panting. Bloodwork shows increased ACTH.
Adrenal glands “a” – normal ratio of cortex to medulla.
Adrenal glands “c” – atrophy of the adrenal cortex bilaterally. This is iatrogenic hyperadrenocorticism.
Adrenal glands “d” – functional adrenocortical tumor. The contralateral adrenal gland has atrophy of the adrenal cortex.
Adrenal glands “b” – adrenocortical hyperplasia (presumably bilaterally). Excessive corticosteroids with bilateral hyperplasia of the adrenal gland and increased ACTH is consistent with a functional pituitary adenoma.
adrenal gland horse
tumor arose from the adrenal medulla.
Diagnosis:
Pheochromocytoma. Potassium dichromate stains the granules within the tumor cells and allows for a quick histochemical diagnosis.
Typical behavior of Pheochromocytoma
Pheochromocytomas may be benign (more commonly) or malignant (more likely to see in dogs than horses). Malignant tumors can infiltrate the vena cava and/or may metastasize widely to other abdominal organs, lungs, brain, etc. Most are small and found as incidental lesions postmortem.
Adrenal gland, kidney, and associated soft tissues from a dog.
Top two differential diagnoses:
Adrenocortical carcinoma or a malignant pheochromocytoma
Name the likely condition and expected clinical signs:
Equine pituitary pars intermedia dysfunction (PPID). Clinical signs include polyuria and polydipsia, muscle weakness, somnolence, intermittent fever, generalized sweating (hyperhidrosis), and hypertrichosis/hirsutism.
pathogenesis of PPID
Decreased dopamine levels in pituitary pars intermedia → loss of inhibition of melanotrophs → excessive production of POMC → increased α-MSH, β-endorphins, and corticotropin-like intermediate peptide (CLIP) → alterations in behavior, insulin resistance, increased ACTH levels (cortisol levels are variable) with Cushing’s-like signs
Skull and pituitary gland from a 16-year-old male castrated cat.
Different cell types of the pituitary gland produce different hormones. If this tumor arose from pituitary corticotroph cells (i.e., those that produce ACTH), what clinical signs would you expect to see in this cat?
Cats with ACTH-producing pituitary adenomas often have diabetes mellitus due to cortisol-induced peripheral insulin resistance and subsequent polyuria and polydipsia (increased urination and thirst). They may also develop severe dermal atrophy and fragile skin. Steroid hepatopathy, which is a feature of this disease in dogs, is NOT seen with this disease in cats.
If this tumor arose from acidophils of the pars distalis, what hormone would be produced by a functional tumor?
Growth hormone
Endocrinopathy and clinical signs caused by excess amounts of hormone from tumor that arose from acidophils of the pars distalis,
tumor makes GH
Feline acromegaly. Clinical signs include increased body size with enlargement of multiple organs, including the heart, kidneys, liver, and parathyroid glands. There is also excessive bone deposition, notably on the skull. Excessive growth hormone can also lead to severe insulin resistance and diabetes mellitus.
thyroid glands
Morphologic diagnosis for the larger thyroid gland:
Associated endocrinopathy:
Severe thyroid adenomatous hyperplasia
Hyperthyroidism
The other thyroid gland is atrophied. What is necessary to diagnose the endocrinopathy?
Hyperthyroidism is a clinical diagnosis and requires measurement of serum thyroxine levels (which will be elevated in hyperthyroidism).
with hyperthyroidism
How would TSH change?
TSH would decline due to feedback inhibition.
thyroid of cat
Based on the changes to the thyroid glands, predict the age of the cat and clinical presentation:
hyperthyroidism
Thyroid adenomatous hyperplasia and hyperthyroidism are associated with older cats with weight loss despite a ravenous appetite, as well as nervousness, tachycardia, heat intolerance, and general weakness.
dog
Name the endocrinopathy and describe the expected clinical signs:
Hypothyroidism. Clinical signs include lethargy, exercise intolerance, heat-seeking, dull mentation, weight gain, and bradycardia. Associated skin changes include scaling, alopecia, myxedema, and regional alopecia of the tail (i.e., “rat tail”).
What changes do you expect in the T4 and TSH levels in this dog?
T4 would be low, and TSH would be high. Note: free T4 is a more reliable measurement for diagnosis than total T4.
hypothyroidism
This cat was euthanized for severe ketoacidosis.
What endocrinopathy does this cat have?
Diabetes mellitus
What antemortem findings would confirm your suspicion of diabetes mellitus?
Hyperglycemia and glycosuria
How is the diabetes mellitus related to the liver changes?
The lack of insulin or inability to uptake insulin at the cellular level results in lipids and proteins being used for energy rather than glucose. With a higher than usual demand for lipids, the body’s fat stores are broken down, and excess amounts of lipid are presented to the liver. The amount of lipid being brought to the liver can overwhelm the liver’s capacity to process it, and lipid accumulates within the cytoplasm of hepatocytes.
Refractory diabetes mellitus in cats can be associated with what other endocrine disorders?
Hyperadrenocorticism
Hypersomatototropism (GH-acromegaly)
Name the skin condition
Hepatocutaneous syndrome/ superficial necrolytic dermatitis (SND)
Severe liver disease (severe idiopathic vacuolar hepatopathy, or vacuolar hepatopathy associated with chronic phenobarbital administration) is one cause for these skin lesions, and the pathogenesis is thought to involve derangements in amino acid production/metabolism. Similar skin lesions have been associated with glucagonoma (neoplasm from alpha cells in the pancreatic islets).
What are the three main histologic features you would expect to see in the skin?
pet has SND (superficial necrolytic dermatitis)
Severe diffuse parakeratotic hyperkeratosis (RED), spongiosis of the stratum spinosum (WHITE), and basal cell hyperplasia (BLUE)
These lesions are bilaterally symmetrical, affecting all four paws as well as the nasal planum and haired skin of muzzle.
This is an example of pemphigus foliaceus, an autoimmune disease. In this disease, autoantibodies are directed against what protein?
Desmocollin-1
Histologically, what would you see in these pustules of animal with pemphigus foliaceus?
Healthy neutrophils and acantholytic cells. Bacteria are not present.
What are THREE major infectious causes of this lesion?
The three top differential diagnoses for folliculitis include
bacteria (usually Staphylococcus pseudintermedius)
demodex mites
dermatophytes- ringworm (fungi)
This case is an example of demodicosis.
