What is your diagnosis? Pituitary mass in a dog

Abstract

A 7-year-old male neutered Boston Terrier, previously diagnosed with hyperadrenocorticism, was presented to the University of Missouri Veterinary Medical Teaching Hospital Neurology service for evaluation of a large pituitary mass revealed on computer tomography (CT) and progressively worsening clinical signs despite treatment. Upon arrival, the dog's vital parameters, including heart and respiratory rate and temperature, were within normal limits. The mucous membranes were dry. The neurologic examination revealed an inappropriate mentation, characterized by drowsiness, absent menace response bilaterally, postural reaction deficits limited to delayed hopping and proprioceptive positioning in the left pelvic limb, while gait was unremarkable and with no obvious ataxia, weakness or lameness, spinal reflexes were intact, and no hyperesthesia could be elicited upon paraspinal palpation. The dog's neuroanatomic diagnosis was bilateral forebrain lesion due to a pituitary macroadenoma and associated peritumoral edema. The CBC (Sysmex XT-2000iV; Sysmex America, Inc, Mundelein, IL, USA) was normal, except for a mild lymphopenia. The chemistry profile (Olympus AU400e; Beckman Coulter, Brea, CA, USA) revealed changes associated with hyperadrenocortism, including mildly increased GGT, ALT, and ALP activities. Additionally, marked hypernatremia, hyperchloridemia, and a mildly decreased corrected chloride concentration were found. Hypernatremia and hyperchloridemia were attributed to marked dehydration due to an altered mental state. The mildly decreased corrected chloride (corrected Cl = measured Cl 9 147/measured Na) suggesting a disproportionate decrease of chloride relative to sodium has been reported with hyperadrenocortism. 1 The increased endogenous ACTH concentration was supporting pituitary-dependent hyperadrenocortism. A transsphenoidal approach for hypophysectomy was taken to remove the mass. Intraoperative imprints were submitted for evaluation ( Figure 1). Figure 1. Imprints of an enlarged pituitary gland in a dog. Wright-Giemsa. 950 objective. A B

Cytologic features of canine melanotroph and corticotroph pituitary adenomas

“…7,[18][19][20] Pituitary neoplasms typically exhibit distinct cytologic features commonly associated with neuroendocrine tumors, including naked or free nuclei within pale cytoplasm lacking distinct borders. 11,12 However, other neoplasms or alterations described in the sellar or suprasellar regions differ significantly from those observed in pituitary adenomas within the scope of this study.…”

“…In one study, 12 postmortem cytology of a pituitary mass in a dog with hypercortisolism revealed features consistent with a neuroendocrine tumor. Subsequent histologic examination confirmed the presence of an invasive pituitary macroadenoma.…”

“…Although pituitary adenomas are relatively common in dogs, there are few reports in the literature describing their cytologic features. In one study, 12 postmortem cytology of a pituitary mass in a dog with hypercortisolism revealed features consistent with a neuroendocrine tumor. Subsequent histologic examination confirmed the presence of an invasive pituitary macroadenoma.…”

“…Cytology does not distinguish among the types of pituitary adenoma, but is still a valuable diagnostic tool 1 to differentiate adenomas from other types of sellar masses such as lymphoma, meningioma, craniopharyngiomas, germ cell tumor, metastatic neoplasms, hypophysitis, and degeneration, both in human and veterinary medicine 7,18–20 . Pituitary neoplasms typically exhibit distinct cytologic features commonly associated with neuroendocrine tumors, including naked or free nuclei within pale cytoplasm lacking distinct borders 11,12 . However, other neoplasms or alterations described in the sellar or suprasellar regions differ significantly from those observed in pituitary adenomas within the scope of this study.…”

“…7 While previous studies provided insights into the histologic and immunohistochemical features of canine and feline pituitary adenomas, 8-10 detailed cytologic descriptions have been reported infrequently in the veterinary literature. 11,12 Hypophysectomy is becoming a more available treatment option and also enables a definitive diagnosis via histopathology and immunohistochemistry (IHC) and allows a more rapid preliminary diagnosis via cytologic evaluation. 8,[13][14][15][16][17] The aim of this study was to describe the cytologic features of pituitary adenomas in 12 dogs that underwent hypophysectomy.…”