Giant splenic myelolipoma in a cat with hyperthyroidism.

Splenic myelolipoma is rarely reported in the domestic cat, with only five cases documented within the literature, and none of these having described giant myelolipoma. Indeed, giant myelolipomas are rarely reported in the human literature and are most commonly adrenal in origin. The pathogenesis of these masses is unclear; there have been several incidences in people with endocrine disorders, and it has been hypothesised that their occurrence may be related to endocrine stimulation. Here we report the first case of giant myelolipoma in a hyperthyroid cat.