Xanthogranuloma

From Dog

Xanthogranulomas are a rare, usually benign, nodular granulomatous inflammatory lesions ('foam-cell tumor') characterized by accumulation of lipoprotein-laden macrophages within epithelial cells.

These granulomas may occur on the skin, such as cutaneous xanthomas or may affect the eye[1] or structures within the sella turcica.

Sella xanthogranulomas are usually observed in older dogs and often associated clinically with hyperadrenocorticism and hypothyroidism[2].

Affected dogs often present with symptoms of lethargy, weakness, anorexia, vomiting, proprioceptive deficits, aggression and seizures.

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 a xanthogranulomatous hypophysitis involving the sella turcica.

Histologically, these lesions have a characteristic appearance consisting of multinucleated giant cells, macrophages, and hemosiderin-laden macrophages with occasional lymphocytes and plasma cells admixed with large regions of cholesterol cleft deposition, fibrin, and prominent Rosenthal fibers.

A differential diagnosis would include lymphoma, hyperadrenocorticism, hypothalamic-pituitary trauma[3], dorsally expanding cysts, inflammatory granuloma, lymphocytic hypophysitis[4], congenital malformations such as empty sella syndrome and neoplasms such as craniopharyngioma, infundibuloma, 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, but would be associated with a poor prognosis due to .

References

  1. Zarfoss MK & Dubielzig RR (2007) Solid intraocular xanthogranuloma in three Miniature Schnauzer dogs. Vet Ophthalmol 10(5):304-307
  2. Cramer SD et al (2011) Sellar xanthogranuloma in a dog. J Vet Diagn Invest 23(2):387-390
  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