CASE 10421 Published on 18.11.2012
0

Left thyroid hemiagenesia

Section

Head & neck imaging

Case Type

Anatomy and Functional Imaging

Authors

Dr. Elton CEKAJ

SRD,imagery,Imaging; mihal duri, 58, 3, 28 28874 Tirana, Albania; Email:eltonceka@gmail.com
Connected authors
Elton Ceka radiologist Albania
Patient

53 years, female

Categories
Area of Interest Thyroid / Parathyroids ; Imaging Technique Nuclear medicine conventional, MR, Ultrasound
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Clinical History
The patient presented to the hospital with anxiety and breathing difficulty. She came to our department to have an ultrasound (US) examination to evaluate the thyroid gland because the doctor noticed an asymmetry in the anterior neck. FT3, FT4 and TSH were within normal values.
Imaging Findings
Ultrasound (US) showed absence of the left thyroid lobe with only a right lobe and isthmus present. Right lobe dimensions were 2.11 x 2.46 x 5.34 and within it there were a colloid cyst and a nodus present. The same findings were present in the isthmus as well and its anteroposterior diameter was 5 mm. US did not show signs of a pyramidal lobe, thyroglossal remnants or ectopic thyroid (Fig 1a, 1b, 1c, 1d). The missing left lobe was confirmed on MRI (axial T1W and T2W, coronal T1W and T2W) (Fig 2a, 2c, 2b, 2d) and by nuclear scintigraphy (Fig 3).
Discussion
Thyroid haemiagenesis is a rare congenital abnormality, in which one of the thyroidal lobes fails to develop. The cause of thyroid haemiagenesis is unclear but is thought to result from cells migrating laterally resulting in a one-lobed thyroid gland with or without an isthmus.[1] The prevalence rate of thyroid hemiagenesis is not well-known but several studies have shown that in the normal population it is 0.05–0.2%. [2–4]
Gursoy et al. have indicated the prevalence of thyroid haemiagenesis as 0.025% in the normal population and 0.25% in patients with thyroid disorders.[5] The first known case was described in 1866 by Handsfield-Jones [6] and the first study on this subject was reported by Marshall in 1895. [7]
Thyroidal haemiagenesis is predominantly seen in females with the left lobe being absent more frequently than the right one in the ratio 4:1. [2]
Thyroidal haemiagenesis by itself is asymptomatic, so cases typically are diagnosed as an incidental finding in routine neck ultrasound for other causes. Thyroid ultrasound usually is diagnostic and other imaging methods are usually not necessary. [2, 8]
CT examination can be diagnostic but administers radiation and injection of intravenous contrast material may be given. Magnetic resonance imaging is useful as well and nuclear scintigraphy (Fig 3) demonstrates absence of uptake in the missing lobe, indicative of haemiagenesis and differentiating it from ectopic thyroidal tissue. [8]
Differential Diagnosis List
Left thyroid hemiagenesis
Thyroid lobe hypoplasia
Ectopic thyroid gland
Thyroid lobectomy
Final Diagnosis
Left thyroid hemiagenesis
Case information
URL: https://eurorad.org/case/10421
DOI: 10.1594/EURORAD/CASE.10421
ISSN: 1563-4086
Figure 1

MRI findings

MRI findings
MRI axial T1W image: The left thyroid lobe is missing. NOTE: slight anterior neck asymmetry
MRI findings
Coronal T1W image. Absent left thyroid lobe. Note the slight deviation of the trachea to the left.
MRI findings
MRI axial T2W image showing the same findings as figure 2a.
MRI findings
Coronal T2W image showing the same findings as figure 2b.
Figure 2

Nuclear scintigraphy study

Nuclear scintigraphy study
Nuclear scintigraphy coronal projection of the neck: There is no nuclear uptake in the left thyroid lobe.
Figure 3

US findings

US findings
Axial scan in the midline: The left lobe of the thyroid gland is missing. NOTE: small colloid cyst is on the right side.
US findings
Axial scan of the right neck: Right lobe anteroposterior and laterolateral diameters are 2.11 cm and 2.46 cm, respectively.
US findings
Longitudinal scan of the right thyroid lobe: Note that a nodus and a colloid cyst are present in the posterior part.
US findings
Axial scan of the isthmus containing a nodus and a small cyst.