A 'silent' skull metastatic follicular thyroid carcinoma mimicking as a benign scalp tumor in a pregnant woman

Abstract

Thyroid cancer with cranial metastasis in a pregnant woman is very rare. In the literature, most cases are diagnosed early from neurogenic signs or symptomatic thyroid gland. Pregnancy also contributes to a hesitation toward early surgical and medical treatments. We reported a scalp tumor in a physically healthy 37-year-old pregnant female with a follicular thyroid carcinoma (FTC) with lung, bone and cranial metastasis in initial presentation. Silent neurogenic and physical examinations make an early diagnosis very challenging. Resection of scalp and intracranial tumor, a thyroidectomy, post-operative radioactive iodine therapy and tyrosine kinase inhibitors were employed as treatment. The scalp tumor was confirmed as a metastatic follicular thyroid carcinoma via positive immunoreactivity for thyroglobulin and thyroid transcription factor 1 in tumor cells. Blood examination revealed an elevated thyroglobulin level (>5335 ng/mL). The patient was discharged without any neurological deficit. An asymptomatic scalp tumor in a pregnant woman with a normal thyroid disease history needs differential diagnosis from intracranial origin. Rapid progression and an elevated thyroglobulin level are the indicators that further image study is needed. Aggressive surgical excision of resectable thyroid gland and metastatic tumor are essential for a longer survival rate. There is nothing to indicate that a post-partum operation will worsen prognosis.

Learning points: Follicular thyroid cancer with cranial metastasis in initial presentation can be asymptomatic.Follicular thyroid cancer with cranial metastasis in a pregnant woman can be treated after delivery.Rapid enlargement of scalp tumor is indicated for further image study even in a patient without any neurological deficit.

Figure 1

First stage of surgery for left scalp tumor. Smooth plane can be dissected above galea plane, but hypervascularity with some engorged vessels were encountered around the base of tumor (A). One 7.0 × 7.0 cm tumor was resected. The surface of tumor (B) was smooth, but some necrotic tissue and bony fragment were identified from basal view (C). Skull bone bony defect highly suggests intracranial origin of this tumor (D).

Figure 2

Frozen section of scalp tumor revealed that there are abundant cube-shaped cells accompanied with light eosinophilic colloid within follicles (H&E stain, 200×).

Figure 3

Contrast-enhanced magnetic resonance imaging (MRI) with contrast after first-stage scalp tumor removal. Horizontal (A), coronal (B) and sagittal (C) view revealed one heterogenous intracranial mass lesion with destroying left parietal and occipital bone skull bone.

Figure 4

Bone scan revealed multiple bone metastases on thoracic, lumbar spine, ilium and sacrum bone.

Figure 5

Positive findings for thyroglobulin (A) and thyroid transcription factor 1 (B) confirm the diagnosis of metastatic thyroid carcinoma.

Figure 6

I131 whole body scan revealed increased radioactivity over bilateral lungs, upper back and pelvic bone area.