Case 653 -- A 47 year old Woman with a Thigh Mass

Contributed by Kelly Garner, MD and Uma Rao, MD


Patient is a 47 year old female who presented to an outpatient clinic with the chief compliant of thigh swelling due to what was thought to be a blood clot. She received a MRI scan which showed an incidental mass in the contralateral thigh. A more thorough MRI confirmed the 7cm heterogenous lesion in her left vastus intermedius. At this point of time, it was felt to be a sarcoma and a biopsy was performed.

A detailed past medical history was obtained and was significant for HTN, thyroid nodules, arthritis, ovarian cystectomies, and tonsillectomy performed in another institute. The relationship of oophorectomy results were not known. The thyroid had never been biopsied.


Specimen consisted of multiple cores and fragments of pale tan soft tissue, ranging in size from 0.2 cm to 1.9 cm in length and <0.1 cm in diameter. The histology showed follicles filled with a pink material lined by flat to cuboidal cells (figs. 1, 2, 3, and 4). There are areas that have a more solid appearance with dark appearing nuclei (fig. 5). Immunohistochemical stains for TTF-1 (fig. 6) and Thyroglobulin (fig. 7) showed a positive staining pattern.


An initial test was performed from the leg specimen to look for the rearranged RET/PTC region and revealed NO RET rearrangement. Further molecular studies were performed and were negative for mutations in BRAF, NRAS61, HRAS61, KRAS12/13. FISH was also done to confirm the initial results and again were negative for the RET/PTC rearrangement.


Based on the above findings, the origin of the mass was unclear. Therefore, additional radiologic studies were performed including a neck US which showed many micronodules and a right thyroid nodule measuring 1 cm in size. Also, the outside slides from her right oophorectomy back in 1986 were obtained for review.


On histology, the right ovary had similar findings as the previously described thigh biopsy which was colloid filled follicles lined by flat to cubodial cells (fig 8). However, this specimen did have more areas that had clear nuclei (figs. 11 and 12) and a focus concerning for vascular invasion (fig. 9 and close up view of an endothelial lined lumen fig. 10). The pathology report from the outside case also reported that the left ovary had a dermoid cyst (slides not reviewed by pathology at Shadyside).


Case IndexCME Case StudiesFeedbackHome