Infundibuloma

From Dog

Infundibuloma are an extremely rare, usually benign, adnexal pituitary neoplasia of older dogs[1].

Infundibulomas are tumors of the ependymal prolongation of the infundibulum (ventral hypothalamus) and involve the third ventricle, infundibulum and neurophypophysis. They may also arise from ependymal cells of the third ventricle.

These tumors are associated with diabetes insipidus and secondary thalamic Frohlich's adiposogenital syndrome.

Clinically affected dogs present with non-neurological symptoms of weight loss, polyuria, polydipsia and lethargy.

Diagnosis is difficult as imaging with CT or MRI may not reveal a mass within the sella turcica, requiring hypophyseal biopsy or exploratory craniotomy.

Definitive diagnosis usually requires intraoperative or postmortem biopsy, verifying infundibular involvement with neoplastic changes. These tumors have the histological appearance of neurhypophyseal tissue, characterized by fusiform cells with long tapering processes occupying a highly vascular stroma. They resemble papillomas of the choroid plexus and hemangiomas and consist of cuboid epithelium either gathered into broad sheets or thrown into papillary projections[2].

A differential diagnosis would include lymphoma, hypothalamic-pituitary trauma[3], dorsally expanding cysts, inflammatory granuloma, lymphocytic hypophysitis[4], congenital malformations such as empty sella syndrome and neoplasms such as xanthogranuloma, craniopharyngioma, pituitary adenocarcinoma[5] and metastatic tumors such as metastatic mammary carcinoma, lymphoma[6], malignant melanoma and pancreatic carcinoma.

Treatment has not been reported with this disease, although hypophysectomy would empirically be effective.

References

  1. Saunders LZ et al (1951) Diabetes insipidus and adiposogenital syndrome in a dog due to an infundibuloma. Cornell Vet 41(4):445-458
  2. Moulton, JE (2002) Tumors in domestic animals. 4th edn. Iowa State Press, Iowa
  3. Foley C et al (2009) Hypothalamic-pituitary axis deficiency following traumatic brain injury in a dog. J Vet Emerg Crit Care (San Antonio) 19(3):269-274
  4. Meij BP et al (2012) Lymphocytic hypophysitis in a dog with diabetes insipidus. J Comp Pathol 147(4):503-507
  5. Goossens MM (1994) Diabetes insipidus in a dog with an αMSH-producing pituitary tumor. Vet Q 16(1):61
  6. Nielsen L et al (2008) Central diabetes insipidus associated with primary focal B cell lymphoma in a dog. Vet Rec 162(4):124-126