Category: Thyroid

Monitor: 6

6 - PAPILLARY THYROID CARCINOMA PRESENTING WITH MULTI-FOCAL SKELETAL MUSCLE METASTASIS

Thursday, Apr 25
1:30 PM – 2:00 PM

Objective :

Skeletal muscle metastases in papillary thyroid cancer (PTC) is rare.  There are a total of 32 reported cases of skeletal metastases from PTC in the literature over the past 110 years.  Herein, we report a case of distant multi-focal metastatic PTC that involves the skeletal muscle.


Methods : N/A


Results :

52 year old man underwent total thyroidectomy in August 2008 for an incidental thyroid nodule.  Pathology reported a 5.5 cm papillary thyroid cancer (PTC) without aggressive histology and 5/7 cervical lymph nodes positive at level 6.  After surgery, he was treated with 177 mCi of radioactive iodine (RAI).  He underwent repeat RAI with 156 mCi in 2010 for evidence of recurrence in the right neck.  In 2011, he underwent neck dissection for persistent structural disease and tumor was identified on the recurrent laryngeal nerve.  Surgery was aborted per the patient’s wishes to leave the recurrent laryngeal nerve intact. He subsequently received his third dose of 293 mCi radioactive iodine treatment with a total of 626 mCi.  In 2013, a surveillance PET-CT reported the neck mass had enlarged and involved the muscular wall of the esophagus. He underwent resection of the neck mass followed by external beam radiation therapy of the esophagus.  Pathology of the neck mass revealed  PTC.  In 2017, he was found to have a soft tissue mass on his right upper arm and PET-CT reported a 3.7x 2.7 x 2.6 cm mass in the upper sternum, as well as multiple intramuscular hypermetabolic lesions in the right upper arm, left trapezius, left gluteus maximus, and left hip abductors with mild hypermetabolic activity at the bilateral thyroid bed, and new 2-3 mm right lung nodules suspicious for metastatic disease. In 2018, he underwent partial sternal resection with removal of a mass from the upper sternum and right arm.  Pathology from both sites was consistent with metastatic PTC.


Discussion :

Muscle metastases from solid tumors are rare and thought to be due to anti-tumor protective mechanisms in the muscle.  The majority of skeletal muscle metastases were from lung (25.1%), gastrointestinal (21%), and urologic tumors (13.2%).  Muscle metastases from thyroid cancer is rare (3.7%).  Only a third of the patients had pain from the muscle metastases and the most frequent site of involvement was the gluteus muscle.  Median survival was reduced by nearly half in patients with skeletal muscle metastases compared to other organ thyroid metastases. 


Conclusion :

Skeletal muscle metastases in PTC is a rare finding.  The possibility of metastatic thyroid cancer to the skeletal muscle should be considered in patients with recurrent PTC.

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Terry Shin

Endocrinologist
Walter Reed National Military Medical Center
Rockville, Maryland

Staff Endocrinologist at Walter Reed National Military Medical Center

Hoang Thanh

Endocrinologist
Walter Reed National Military Medical Center

Staff Endocrinologist and Program Director for Endocrinology Fellowship at Walter Reed National Military Medical Center

Mohamed Shakir

Endocrinologist
Walter Reed National Military Medical Center

Staff Endocrinologist at Walter Reed National Military Medical Center

Vinh Mai

Endocrinologist
Walter Reed National Military Medical Center

Staff Endocrinologist and Service Chief at Walter Reed National Military Medical Center