Midline thyroid: a developmental anomaly??

[Ronaldo2]

I  was diagnosed with subclinical hypothyroidism in Sept 2011. It was monitored with thyroid blood tests until it was found to have progressed to cllinical hypothyroidism in March, 2012. I have never had any symptoms. It was diagnosed early. My doctor noticed I had a midline lump at the front of  my neck which he guessed was a thyroglossal duct cyst. I have had it for tens of years but my wife thinks (using a little imagination??) that it has grown slightly  in the last 1/2 year. It is symmetrical, non-tender etc. My thyroid autoantibodies were negative when tested a few months ago. I am on Synthroid, a small dose of 25 mcg/day.
Today I had an ultrasound scan on my midline (approx) 1-2 cms diameter lump: the radiologist said it was hypervascular solid tissue, NOT a cyst. There was also some micro- and macro-calcification. I am heading for an FNA as soon as it can be arranged.
But I'd love your thoughts on the possibility that this midline lump is a remnant of thyroid tissue from incomplete development or descent of thyroid tissue into my neck (they found very little thyroid tissue in the usual place for thyroid tissue on US scan today).
Is the microcalcification likely to be just an incidental finding?
On what basis can I get hypothyroidism with negative autoantibodies to thyroid? Is this common?

[898_1]

Yes those are synonyms; for Hashi's there should be large amounts of lymphocytes as macrophafes are associated with other types of thyroid inflammation. stromal cells are  cells of connective tissue.

[Ronaldo2]

Thank  you 898_1. That is the 1st I've heard of Afirma. Your knowledge is impressive! Can discuss that with Endo next visit (presuming it isn't urgent) in 3 months' time.

Regarding your comment on Hashi's Dx from biopsy report, my report showed "...cell block preparation shows stromal cells, inflammatory cells and a small group of follicular epithelial cells... a specific diagnosis cannot be made"  
The reference to inflammatory cells is non-specific: presumably that would include lymphocytes? Does  that favour the diagnosis of Hashi's?
The microscopy report on the slide preparations showed "groups of follicular epithelium...mild nuclear size variation but no obviously malignant features. No nuclear grooves or pseudo-inclusions identified...no psammoma bodies... copious colloid...scattered hemosiderin-containing macrophages are seen".   Do the latter macrophages qualify as the "foamy macrophages" you mentioned above?

I'm not sure that my Endo, whose field of specialization is actually predominantly diabetes, is aware of those points you've noted.

MANY many thanks for  your comments and expertise.  

[898_1]

Hashimoto's confirmed by biopsy if foamy macrophages and lymphocytes are present in the sample
You may ask about Afirma molecular test to evaluate risks of cancer (the test is applied to the specimen collected at biopsy).

[Ronaldo2]

Thanks 898_1
An update! As above, USS report showed BOTH types of calcification, micro- and macro- which was the indication for proceeding to a subesequent FNA biopsy : it showed stromal cells, groups of follicular epithelium, inflammatory cells, no obvious malignant features. Features favour "benign follicular lesion".
CT scan simply confirmed that upper neck lump was ectopic thyroid tissue. Ectopic thyroid also present near hyoid bone and at base of tongue(none in upper chest). No thyroid tissue seen in the usual thyroid position. Autothyroid Ab screen was negative as were other tissue auto-Ab's.  
My intuition tells me that I have antithyroid-Ab-negative Hashimoto's Disease but the Endo opined that it was NOT autoimmune but instead labelled it idiopathic hypothyroidism + anomalous thyroid. Your thoughts?

He discussed excision-biopsy with me but I have decided against it : I accept the risk of missing a cancer and also happy to accept the minor barely noticable cosmetic appearance. What would you do?

[898_1]

while reviewing report please look for the type of calicfication (coarse subtype has inflammatory origin, while microcalcification suggests neoplastic process)

[Ronaldo2]

THank you for  your comments. You sound very informedand are very helpful, especially you comment about old inflammation being a possible cause of the calfication: I will cling to the hope that that is the explanation in my case, rather than an underlying neoplastic cause! Had a CAT scan yesterday, awaiting results. Having an FNA biopsy (U/S guided) after that. I still wonder why the midline lump has grown in the last 1/2 year coinciding with the diagnosis and progression of my hypothyroidism from subclinical to overt hypothyroidism? Wondering whether a larger dose of Synthroid ( to achieve high normal range T3 and T4 and very low TSH levels)  may help to produce disuse atrophy thereby shrinking the size of my anomalous thyroid tissue lump and avert surgery?