Left Lobe Agenesis
54 year old man being evaluated due to vague symptoms. Underwent routine clinical workup. Thyroid ultrasound at the right hand side, showed asymmetry of the thyroid gland by absence of the left lobe, which was considered an anatomical variant. The right lobe measures 4.7 x 1.3 x 1.6 cm in longitudinal axis, anteroposterior and transverse, respectively. Isthmus thickness of 0.2 cm. Its internal structure is homogeneous, there is no impairment of the vascular flow with color Doppler ultrasound study.
Afterwards, a thyroid scan was requested, at the left hand side. The right lobe is in normal position. The size is slightly increased in longitudinal diameter. Presents a homogeneous distribution of the radiotracer. Partial visualization of the isthmus. The left lobe was not seen (arrow pointing to empty bed). Study consistent with left lobe hemiagenesis. There is no history of previous thyroidectomy.
This a rare disorder with prevalence of 0.025% in the normal population. Thyroid hemiagenesis appears to be more frequent in the left side. Similar conditions affecting the normal thyroid gland may present in the remnant parenchyma, chronic thyroiditis, Grave's disease, hypothyroidism, adenocarcinoma, adenoma, multinodular goiter. Differential diagnosis may be necessary with Plummer's disease.
References:
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2 Peña S, Robertson H, Walvekar RR. Thyroid hemiagenesis: report of a case and review of literature. Indian J Otolaryngol Head Neck Surg. 2011 Apr;63(2):198-200.
3 Gursoy A, Anil C, Unal AD, Demirer
AN, Tutuncu NB, Erdogan MF. Clinical and epidemiological characteristics of
thyroid hemiagenesis: ultrasound screening in patients with thyroid disease and
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