Long-term management and postmortem examination in a diabetic cat with acromegaly treated with two courses of radiation therapy

Abstract

A 12-year-old, castrated male cat with diabetes mellitus was diagnosed with acromegaly and examined with magnetic resonance imaging (enlarged pituitary gland, 8 mm); serum hormone concentrations were measured. After the first course of radiation therapy (4 Gy, 12 fractions), insulin administration was not required from day 420 after diagnosis. Enlarged pituitary tumor (8 mm) recurred, and insulin dosage amount of the cat was increased on day 1,065. The second course of radiation therapy (6 Gy, 4 fractions) was performed on day 1,201 and insulin administration was again discontinued. However, the cat died from lymphoma on day 1,397. Postmortem examination revealed pituitary adenoma. Most tumor cells were positive for chromogranin A, synaptophysin, and growth hormone immunohistochemistry. The pancreatic islet cells revealed diffuse hyperplasia. We achieved long-term successful management of an acromegalic cat with two courses of RT. However, a protocol for a second course of RT for feline recurrent pituitary tumor should be further discussed.

Evaluation of hypophysectomy for treatment of hypersomatotropism in 25 cats

“…1,2,10 Described treatment modalities for hypersomatotropism include medical treatment, radiation therapy, cryotherapy, and surgery. 2,[11][12][13][14][15][16][17][18][19][20][21] In humans, surgery is the definitive treatment of choice for hypersomatotropism. 22 In 2010, successful treatment by transsphenoidal hypophysectomy of a cat with hypersomatotropism and insulin-resistant DM was reported.…”

“…Treatment of DM by exogenous insulin is often unrewarding as long as the primary hypersomatotropism remains untreated; insulin resistance is common and high doses of insulin may be required 1,2,10 . Described treatment modalities for hypersomatotropism include medical treatment, radiation therapy, cryotherapy, and surgery 2,11‐21 . In humans, surgery is the definitive treatment of choice for hypersomatotropism 22 .…”

Successful treatment of feline hyperadrenocorticism with pituitary macroadenoma using radiation therapy: a case study

“…The major cause of feline pituitary tumors is acromegaly secondary to an increased growth hormone-inducing tumor. Treatment for feline acromegaly has been widely reported, and RT is known to be effective [2,7,9,13]. Another type of pituitary tumor is secondary to an increased ACTH-producing tumor.…”

Relationship between anti-insulin antibody production and severe insulin resistance in a diabetic cat

“…Abdominal ultrasound examination revealed normal-sized adrenal glands (left, 3.3 mm; right, 4.6 mm). Thyroxine levels (1.46 μg/dl; reference interval: 0.5-4.0 μg/dl) and insulin-like growth factor-1 (IGF-1) levels (98 ng/ml; reference interval: mean = 365.9, SD = 192; n = 15) were normal [16]. This led to the exclusion of concurrent hyperadrenocorticism, hyperthyroidism, and acromegaly.…”