Thymofibrolipoma in a Labrador Retriever

Abstract

While thymomas are uncommon but well-known mediastinal masses, collagen-rich variants are exceedingly rare. Thymofibrolipoma and sclerosing thymoma tumor variants have been recently recognized in medical pathology, and thymofibrolipoma has been only rarely reported in dogs. A cranial thoracic mass was identified in a 6-year-old Labrador Retriever that was characterized by robust collagenous stroma dissected by thin cords of cytokeratin-positive neoplastic epithelial cells and bordered by mildly pleomorphic epithelial cells with occasional lymphocytic aggregates and rare Hassall corpuscles. To the authors' knowledge, this is only the second report of thymofibrolipoma in veterinary medicine and the first to describe a variant with a mitotically active and relatively pleomorphic, adjacent thymic epithelial population.

Mixed thymic tumor in a rooster: gross and histological features

“…The only case report of similar types of this tumor mass was reported in Labrador Retriever dog that diagnosed with thymofibrolipoma present in the collagenous stroma (15).…”

Canine Epithelial Thymic Tumors: Outcome in 28 Dogs Treated by Surgery

“…In fact, two main issues are present when differentiating thymomas from other mediastinal masses: the macroscopic differentiation by imaging from space-occupying masses, and microscopic differentiation from lymphoma before histology of the resected mass is performed. The differential diagnosis should be primarily versus mediastinal lymphoma, but other space-occupying masses should also be ruled out, such as branchial cysts, ectopic thyroid or parathyroid tumors, chemodectoma, thymic cysts, metastatic neoplasia, abscesses, granulomas, and other rarer thymus disorders such as thymolipoma and thymofibrolipoma [18][19][20][21]. MG was not resolved in two cases but was managed with lifelong pyridostigmine administration; hypercalcemia was resolved after surgery but recurred in the dog with thymic carcinoma at the time of tumor recurrence.…”