Abstract
Purpose
The purpose of this study is to present a case series and review recommendations within the literature concerning thyroid hemiagenesis.
Materials and Methods
This is a (1) retrospective case series review of 5 patients and (2) literature review (using Medline) on thyroid hemiagenesis.
Results
Most reported cases are female with the left thyroid lobe absent. Compensatory hypertrophy occurs in most thyroid remnants. Associated diagnoses in the remaining lobe include hyperthyroidism, hypothyroidism, simple and multinodular goiter, and carcinoma. There is no increased risk for the subsequent development of cancer in the remaining lobe, and empiric thyroidectomy is not justified.
Conclusions
Thyroid hemiagenesis is an uncommon presentation that is frequently asymptomatic and detected incidentally when imaging for another condition. Awareness of its existence can help prevent unnecessary interventions associated with incorrect assumptions in patient care.
1
Introduction
Abnormalities in thyroid development are well described in the literature. However, thyroid hemiagenesis is an uncommon congenital abnormality in which 1 thyroid lobe fails to develop. The isthmus may or may not be present.
The true prevalence of this diagnosis is unknown because the absence of 1 thyroid lobe is usually asymptomatic. It is frequently diagnosed at the time of assessment for another condition or during evaluation of other thyroid-related conditions. Similar disorders seen with normal thyroid development may present within a hemithyroid remnant. We present 5 cases of asymptomatic thyroid hemiagenesis and review recommendations within the literature concerning the diagnosis.
2
Methods
Approval from the Institutional Review Board (Tufts Clinical and Translational Science Institute) was obtained for medical record review. A retrospective review was performed on 5 case records of patients with thyroid hemiagenesis diagnosed at Tufts Medical Center between the years 2006 and 2010.
A literature review using the PubMed database with the key words “thyroid hemiagenesis” was performed. When available, information regarding sex, side of the absent lobe, and pathology in the existing thyroid lobe was noted for each case of thyroid hemiagenesis identified. Articles without applicable information were eliminated from review. One hundred seven articles were identified for analysis.
2
Methods
Approval from the Institutional Review Board (Tufts Clinical and Translational Science Institute) was obtained for medical record review. A retrospective review was performed on 5 case records of patients with thyroid hemiagenesis diagnosed at Tufts Medical Center between the years 2006 and 2010.
A literature review using the PubMed database with the key words “thyroid hemiagenesis” was performed. When available, information regarding sex, side of the absent lobe, and pathology in the existing thyroid lobe was noted for each case of thyroid hemiagenesis identified. Articles without applicable information were eliminated from review. One hundred seven articles were identified for analysis.
3
Results
Of 5 patients identified at our institution with thyroid hemiagenesis, 4 were female. All 5 patients had absence of the left thyroid lobe. All cases of thyroid hemiagenesis were incidentally discovered on computed tomographic imaging obtained during assessment for unrelated conditions ( Fig. 1 ). Patient characteristics and findings are summarized in Table 1 .
| Age at diagnosis | Sex | Absent lobe | Thyroid status | Goitrous remnant | Pathology in remnant |
|---|---|---|---|---|---|
| 29 | M | Left | Euthyroid | Y | None |
| 31 | F | Left | Euthyroid | N | Sub-cm nodules |
| 48 | F | Left | Subclinical hyperthyroid ⁎ | Y | Multinodular goiter |
| 66 | F | Left | Euthyroid | Y | Multinodular goiter |
| 89 | F | Left | Hypothyroid | N | Sub-cm nodule |
PubMed search revealed 329 cases of thyroid hemiagenesis in reports published between 1970 and 2010. Absence of the left lobe was more frequent, and females accounted for most cases. Results are summarized in Table 2 .
| Sex | Side | ||
|---|---|---|---|
| Female | 157 | Left | 172 |
| Male | 40 | Right | 35 |
| Unspecified | 132 | Unspecified | 122 |
| Total | 329 | ||
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