Rarely normal thyroid tissue may occur within the lung. This is often asymptomatic but can be misdiagnosed as a primary or metastatic tumor on imaging studies.


Frequency: very rare (1 in 100,000)


Risk factors:

(1) female gender

(2) Asian

(3) thyroid disease


The patient may be worked up for:

(1) assessment of a lung nodule

(2) assessment of possible metastasis from a thyroid carcinoma

(3) assessment of possible metastasis from other tumor

(4) source of a malignant thyroid carcinoma

(5) symptoms caused by the ectopic tissue (most patients are asymptomatic)



(1) A biopsy of the lesion shows normal thyroid tissue.

(2) Location in a upper lobe.

(3) Visible on a thyroid scan with I-131.


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