Scapular metastasis as an initial diagnosis of papillary thyroid cancer
Thudi V, and Levy S. Scapular metastasis as an initial diagnosis of papillary thyroid cancer. Endocrine Reviews 2017; 38(3)
BACKGROUND: Papillary thyroid cancer (PTC) is the most common malignancy of the thyroid gland. It very rarely presents with distant metastasis. We present a case of PTC with metastasis to the scapula as the initial presentation. CASE DESCRIPTION: 61 years old Caucasian female presented with left (L) shoulder pain ongoing for the last 1 % years. Her past medical history is significant for a total thyroidectomy due to a thyroid goiter causing neck pressure and voice changes. The pathology report documented a 6 cm adenomatous nodule, and a small benign lymph node. 13 years later, she presented with excruciating L shoulder pain. X-ray noted bony irregularity and fragmented appearance of the L inferior scapular tip. MRI of the shoulder joint showed large destructive posterior shoulder mass (10.4 x 4.3 x 10 cm), destruction of the mid to posterior scapular body, involvement of the teres minor/major and sub scapularis. Biopsy of the mass came as metastatic follicular variant of PTC. Bone scan: focal uptake of L scapula consistent with the site of known mass. Abdomen/pelvis/Chest CT: 11.5 cm mass of scapula, multiple small lung nodules, and multiple liver lesions. Neck ultrasound had no concerning sonographic features and no residual thyroid tissue. Initial treatment was with Thyrogen stimulated radioactive iodine (RAI) therapy. At the time, FT4: 1.29(0.80 - 1.80 ng/dL), TSH: 56.37(0.30 - 5.00 uIU/mL ), Thyroglobulin: 24983(<35 ng/mL), Thyroglobulin Antibody (Th Ab) : 101 (<60 U/mL). Thyroid cancer whole body scan: Uptake at 24 hrs: 1.3% in the L scapula, 1.0% in the thyroid bed. She was treated with 255 mCi of oral I-131. Post treatment I 131 scan showed essentially unchanged radioiodine uptake. Therefore, it was determined that the cancer had dedifferentiated and was no longer iodine avid. Next she received external beam radiotherapy to the L scapula. 2 months later, MRI of L shoulder showed no significant change. Finally, she underwent a metastasectomy with partial resection of the L scapula. Pathologic diagnosis was metastatic follicular variant PTC (9.0 x 7.5 x 4.3 cm) with negative margins. Post-surgical thyroglobulin dropped to 111 (<35 ng/mL) with Th Ab <15 (<60 U/mL ).Her pain decreased from 10/10 to 0/10 post operatively. Currently she is maintained on levothyroxine 200 mcg, 7.5 tabs per week with a goal of a suppressed TSH. CONCLUSION. On review of the literature, only 3 cases of metastatic PTC to the scapula have been reported. Our patient's presentation is unique as she did not have known PTC (pathologic diagnosis of the thyroidectomy was benign), yet 13 years later, she presented with bony metastasis at an atypical site of scapula. This illustrates the importance of appropriate pathological diagnosis. To our knowledge, we present the first case of metastatic PTC to the scapula, without a known history of PTC.