P-096 a Submental Ectopic Thyroid Gland: Case Report of Strange Presentation

Abstract Introduction Ectopic thyroid gland is a rare condition, could be associated with hypo or hyperthyroidism, with or without normally positioned thyroid tissue and occurs due to embryogenic defect. Here we present a 44 years old female with submental mass proved by biopsy to be thyroid tissue. Thyroid ectopia (TE) means presence of thyroid tissue at position other than its normal site (below the larynx and anterior to 2nd-4th tracheal cartilages) due to genetic defects during embryonic journey of thyroid gland (TG), firstly described in 1869 at basis of the tongue(1). Prevalence of ectopic thyroid gland ( ETG) is 1 per 100,000-300,000, more in females, could present with eutopic TG and the lingual ETG is the most common site, but could occur everywhere in the body and even sometimes could occur in 2 or 3 different sites at the same time(1). Clinical Case A 44 years old female patient presented with a 15 years history of painless, slowly growing submental lump, no dysphagia, dyspnea, fever or history of trauma. There was non-tender, mobile, 4 cm x 2 cm smooth surface submental swelling. She has mildly elevated TSH 5.05 mIU/L (0.2 – 4.2 mIU/L) and normal Free T4. Neck ultrasound (US) revealed no TG at its normal position, submental right sided small rudimentary thyroid – like soft tissue lesion (ETG) with large lobulated margin, 4cm x 2cm x 3cm solid isoechoic nodule. FNAC was not conclusive, true cut biopsy showed multiple thyroid follicles of variable sizes with colloid. Patients with ETG may be asymptomatic or have dyspnea, dysphagia and about 70% percent of patients have hypothyroidism (HT) due to impairment of the supplying vessels (2). Ectopic TG also liable to develop thyroiditis, benign nodules and even malignancy (3). Incidence of malignancy in ETG is 1% and most commonly be follicular. (4). In about 70-90% of cases no normally positioned thyroid tissue, hypothyroidism is common but hyperthyroidism is very rare (5). Branchial cyst, thyroglossal or epidermoid cyst, lymph node, lipoma and malignancy should be kept in mind as other diagnoses in any submental mass (5). If there was suspicion about diagnosis or malignancy is suspected, FNAC is indicated with about 95%–97% accuracy (5). Neck US is useful to detect ETG and examine the normal site of TG, other imaging modalities like CT or MRI also can be used, but still the technetium-99 scintigraphy is the main test to detect site, shape, extension and activity of both ectopic and orthotopic TG(5). Follow up only is needed if the patient is asymptomatic, hypothyroidism should be treated and surgical intervention is indicated for those patients with symptoms like dyspnea, dysphagia or bleeding(5). Conclusion Ectopic TG must be considered during assessment of any neck swelling, so neck US, TFT and FNAC (if indicated) should be done to evaluate the mass and examine for orthotopic TG to avoid superfluous surgery which makes the patient in permanent hypothyroidism.Figure 1:Figure shows patient photo, US finding & biopsy finding. Table 1:Summary of the case