[Association of thyrolipoma and thyrolipomatosis: A case report].

We report a rare case of thyrolipoma-thyrolipomatosis' association. A 48-year-old patient, with a past history of high blood pressure and chronic renal failure secondary to AA amyloidosis, presented with a midline neck swelling increasing in size since one year. Ultrasound showed a multinodular goiter, the worst nodule was left-lobar and categorized as EU-TIRADS 4. Grossly, cut section of the thyroïd specimen showed a yellow-tan left-lobar nodule measuring 2.5cm, the surrounding tissue had a diffuse yellow-brown appearance with scattered whitish areas. Histopathologic examination revealed that the nodule corresponded to a follicular adenoma.Thyroid fat infiltration was noticed both within the nodule and in the neighboring parenchyma. Thus, the diagnosis of an association thyrolipoma-thyrolipomatosis was rendered. The association of thyrolipoma-thyrolipomatosis is a very rare occurrence of unclear pathogenesis. To the best of our knowledge, this report describes the second case in the literature. The diagnosis is retained on the basis of certain histological features, revealing mature adipose tissue within thyroid gland as a combined nodular and diffuse pattern.