Endocrinology Fellow Hospital Municipal San Juan San Juan, Puerto Rico, United States
Introduction : Follicular Thyroid Cancer (FTC) is the second most common type of thyroid cancer. FTC accounts for 12% of all thyroid Cancers and tend to occur in the fourth to sixth decade of life and is three times as common in the female population. Twenty percent of the cases can arise from a follicular adenoma, 10-15% of FTC can metastasize to bone and appear as lytic lesions. Literature has described cases of late metastatic complications in which tumors arise on average 4.5 year after initial presentation, in our case this complication developed after 24 years.
Case(s) Description : I present a case of a 77 year old female with past medical history of post surgical hypothyroidism, hypertension and dyslipidemia referred for evaluation of newly found thyroid nodules. Patient had a history of a Left thyroid lobectomy for a 1.7cm solid nodule with echogenic rim on 1999. Post surgical pathology reported a follicular adenoma with Hurthle cell pattern, described as well defined and focally calcified. Patient had no further treatment and was asymptomatic for over 20 years until last year when she developed left hip pain. Hip CT scan revealed a lytic lesion in the left iliac bone with bone destruction. This was suspected to be a metastatic, CT guided biopsy was done and pathology confirmed a metastatic carcinoma from thyroid origin. Molecular testing from bone biopsy specimen was done and showed NRAS and TERT mutations.
On our initial evaluation, Thyroid US results showed: 3 nodules on the right hemithyroid: one isoechoic at lower pole measuring 1.0 x 0.4 x 0.9 cm, wider than tall, ill-defined , the second one was hypoechoic measuring 0.9 x 0.4 x 0.9 cm solid, wider than tall, lobulated and last one hypoechoic solid wider than tall ill-defined of 0.7 x 0.6 x 0.7 cm in size and no worrisome features on neck lymph nodes. Previous Chest CT demonstrated numerous sub centimeter lung nodules which could be metastatic in nature. Laboratory work up was remarkable for normal thyroid function tests and Thyroglobulin Antibodies but a significantly elevated Thyroglobulin Quantitative >502 ( 0.59-50.03 ng/ml). Patient was referred to a high volume surgeon for a right lobectomy. Pathology of this specimen reported Hyperplastic Adenomatous nodules which ruled them out as the cause of the bone lesion.
Discussion : As stated before literature has shown cases in which Follicular adenomas metastasize or with time develop into FTC. The patient was managed properly according to guidelines as benign lesions are not typically followed long term. But cases like ours raise the question if Follicular adenomas would benefit from long term follow up with imaging , thyroglobulin or both and if so, for how long.
