Synchronous Metastatic Follicular Carcinoma and BRAF Mutated Papillary Carcinoma Thyroid—a Rare Occurrence

Excerpt

A 71-year-old female presented with complaints of pain and swelling over the left temporal region of 3 months’ duration. MRI of the orbits showed lobulated altered signal intense mass lesion in the left infratemporal region causing destruction of squamous part of the left temporal bone, greater wing of the sphenoid, and lateral wall of the left orbit measuring 46 × 34 × 39 mm. The mass was extending into the middle cranial fossa compressing the temporal lobe and extending into the intraconal space of left orbit displacing the lateral rectus and optic nerve laterally suggestive of metastatic deposit. Fine needle aspiration cytology from the same showed metastatic deposits of papillary thyroid carcinoma. Contrast-enhanced CT neck showed evidence of heterogeneously enhancing hyperdense soft-tissue mass involving the left anterior temporal region, extending into left orbit, left infratemporal fossa, soft tissues of adjacent scalp causing destruction of the left fronto-temporal bone, greater wing of sphenoid, and left lateral wall of orbit measuring about 44 × 38 × 34 mm. Multiple hypodense nodules were seen in both lobes of thyroid gland with left lobe nodules showing rim calcification, suggestive of carcinoma thyroid. Tc 99 m–MDP bone scan confirmed metastases at only the left temporal region and excluded any additional metastatic foci. Total thyroidectomy was done and sent for histopathology examination. Grossly left lobe showed a lesion measuring 1.2 × 1.2 × 1 cm and a separate nodule measuring 0.5 × 0.5 × 0.2 cm seen 1 cm away from this lesion. Microscopy favored synchronous (mixed) follicular carcinoma which showed capsular invasion (minimally invasive) and papillary carcinoma thyroid (encapsulated classic papillary microcarcinoma) involving the left lobe of thyroid with the two tumors separated by normal thyroid parenchyma. Immunohistochemistry by BRAF V600E was positive in papillary thyroid carcinoma and negative in follicular thyroid carcinoma (Fig. 1). Isthmus and right lobe of thyroid were unremarkable. Patient was given adjuvant radioactive iodine (RAI) therapy. The 36-week follow-up of this patient is uneventful.

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