Thyrolipomatosis: A case report with review of the literature

Abstract

Abstract. Fatty tissue is not usually present within the thyroid gland. Only a few fat-containing thyroid lesions have been reported to date, and thyrolipoma is the most common fat-containing lesion of the thyroid gland. Thyrolipomatosis is a condition characterized by diffuse mature adipose cell infiltration of the normal thyroid gland. In this report, we describe what is, to the best of our knowledge, the 12th documented case of thyrolipomatosis, and review the fat-containing lesions of the thyroid gland. A 68-year-old Japanese woman presented with a neck mass that had first been noticed ~7 years earlier.A computed tomography scan revealed diffuse thyroid gland enlargement and total thyroidectomy was performed. The histopathological examination revealed that mature fatty tissue was diffusely distributed throughout the thyroid gland, as well as among the hyperplastic follicles. Capsular formation or amyloid deposition were not observed. Nuclear grooves or intranuclear cytoplasmic inclusions were not observed. Accordingly, thyrolipomatosis was diagnosed. Albeit rare, various neoplastic and non-neoplastic thyroid lesions may contain mature fatty tissue. Therefore, thyrolipomatosis must be included in the differential diagnostic consideration of fat-containing lesions of the thyroid gland. IntroductionAlthough there is usually no mature fatty tissue within the thyroid gland, fat-containing thyroid lesions have been reported (1). Fat-containing thyroid lesions may be classified into two groups, namely neoplastic and non-neoplastic lesions. Thyrolipoma, also referred to as lipoadenoma, is the most common fat-containing lesion of the thyroid gland; it is considered to be a variant of follicular adenoma and is characterized by the presence of mature adipose cells interspersed throughout the follicular adenoma (2). Moreover, a few cases of papillary carcinoma and follicular carcinoma with adipose cells have been reported (1). Non-neoplastic fat-containing thyroid lesions include amyloid goiter and Hashimoto thyroiditis (1,3).Albeit extremely rare, diffuse mature adipose cell infiltration of the normal thyroid gland has been previously reported, referred to as thyrolipomatosis or diffuse lipomatosis of the thyroid gland (2). To the best of our knowledge, only 11 cases have been documented in the literature to date (2,4-8). We herein describe an additional case of thyrolipomatosis and review the fat-containing thyroid lesions. Case reportA 68-year-old Japanese woman with a past history of diabetes mellitus and angina pectoris presented at the Kusatsu General Hospital in August 2016 with a neck mass that had been noticed ~7 years earlier. A computed tomography scan revealed diffuse thyroid gland enlargement, compressing the trachea, with multiple calcifications in the bilateral lobes. The serum thyroid-stimulating hormone and free thyroxine (FT4) levels were within the normal range (0.63 µIU/ml, range 0.4-4.0 µIU/ml; and 1.01 ng/dl, range 0.8-1.7 ng/dl, respectively), but the free triiodothyronine (FT3) level was mildly d...

Coexistence of Thyrolipomatosis and Tongue Squamous Cell Carcinoma: A Case Report

“…Examples of neoplastic lesions include thyrolipoma, papillary carcinoma and follicular carcinoma, while examples of non-neoplastic lesions include an adenomatous nodule, thyrolipomatosis, amyloid goitre, dyshormonogenetic goitre and Hashimoto’s thyroiditis. 18 …”

“…The characteristic histopathological feature is the presence of mature fatty tissue in the follicular adenoma and a fibrous capsule around the tumour. 18 Amyloid goitres are also a relatively common nonneoplastic thyroid lesion that contains fat. The presence of amyloid among non-neoplastic thyroid follicles is characteristic of this condition, and Congo red staining is positive.…”

An Enlarged Goiter Presenting with a Rare Diffuse Lipomatosis of the Thyroid Gland

“…Thyrolipomatosis is a rare and benign condition of the thyroid gland resulting from diffuse stromal infiltration by mature adipose tissue [ 5 ]. Dhayagude first observed the entity in 1942 [ 3 ].…”

“…In 2016, Bell and colleagues reported a case of thyroid lipomatosis and reviewed the cases of 20 previously reported patients [ 4 ]. Since then, 4 additional cases were reported in the literature [ 2 , 5 – 7 ].…”

“…The differential diagnosis of fat in the thyroid gland falls into 2 groups: benign entities (e.g., thyrolipoma [also known as adenolipoma], heterotopic nests of adipocytes, amyloid goiter, lipid-rich thyroid follicular adenoma, parathyroid lipoma, and lipomatosis) and malignant neoplasms (e.g., liposarcoma) [ 1 , 4 , 5 , 8 ]. Thyrolipoma is a well-circumscribed and encapsulated nodule composed of a proliferation of thyroid follicles admixed with mature adipose tissue [ 9 ].…”